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SPATIO-TEMPORAL PATTERNS OF LANDBIRD MIGRATION ON THE LOWER DELMARVA PENINSULA INTERIM REPORT Written by: Bryan D. Watts Center for Conservation Biology College of William and Mary Sarah E. Mabey Department of Conservation and Recreation Division of Natural Heritage Project sponsored by: Virginia Department of Environmental Quality Virginia Coastal Resources Management Program Virginia Department of Conservation and Recreation Division of Natural Heritage Virginia Department of Game and Inland Fisheries Nongame and Endangered Species Program September 1993 This paper is funded in part by a grant from the National Oceanic and Atmospheric Administration. The views expressed herein are those of the authors and do not necessarily reflect the views of NOAA or any of V-0 its sub-agencies. 00 4! 1 Ror,@d, by'Dap!, @,,f E T I V,;.r @); e! 41 au;@ I i i y I FEB !"n" I Public & lntp(- governmental.Affains t I I I I I t i I I I I I I I I I SPATIO-TEMPORAL PATTERNS OF LANDBIRD MIGRATION ON THELOWER DELMARVA PENINSULA INMRIM REPORT Written by Bryan D. Watts Center for Conservation Biology College of William and Mary Williamsburg, VA 23185 Sarah E. Mabey Department of Conservation and Recreation Division of Natural Heritage Main Street Station, Suite 312 Richmond, VA 23219 00 September 1993 EXECUTIVE SUMMARY Reported declines of neotropical migratory songbird populations have drawn the attention of the scientific community and the general public. While researchers and conservationists have focused their energies on understanding the behavioral and ecological dynamics of these population during the breeding and wintering season, migration ecology has remained largely neglected. Migration must be endured twice annually and is a particularly stressful event for birds. Comprehensive conservation efforts on behalf of migratory birds must include this critical phase of life if they are to succeed in protecting whole populations. The two-year Northampton Migratory Bird Project (NMBP) was initiated under Northampton County's Special Area Management Plan (SAMP) to provide this rural, coastal county with sound scientific data to guide the development of enforceable policies that will protect and enhance migratory songbird habitat. Conserving migratory birds and their habitat in lower Northampton County will serve to generate the basis of a burgeoning nature tourism industry, help to protect water quality and moderate secondary impacts of coastal development. Results from the first season of the study show some strong spatial and temporal patterns. In summary, our data indicate: 1. Long-distance migrants are most abundant during the first half of the migratory period while short-distance migrants are most abundant during the last half of the season. 2. Bird activity was greater in the morning compared to the afternoon. 3. If birds spatially redistribute during the course of a day, they do so very early in the morning. 4. Many long- and short-distance migrants concentrate along the bayside and near the tip of the peninsula. Resident species tend to be least abundant near the peninsula tip. 5. In general, there is no clear relationship between bird abundance and patch size. 6. The majority of birds from both migrant groups were more abundant close to the forest edge than in the interior. 7. Most species overutilized plots with relatively high vegetation density. 8. Individual species were associated with particular vertical strata within the forest. The vertical distribution of species is in general agreement with associations known for the breeding and wintering seasons. The results of the first year provide a critical step toward policy development and land use planning for the protection of migratory songbirds and their habitat in Northampton County, Virginia. INTRODUCTION The recent surge of interest in neotropical migratory songbirds spans the realms of science, conservation and the general public and has provided a common ground for the interaction of these diverse circles. Reports of population declines for many eastern neotropical migratory songbird species (Hill and Hagan 1991, Askins et al. 1990, Robbins et al. 1989) have focused attention on the problems of temperate forest fragmentation and tropical deforestation (Hagan and Johnston 1992). The general environmental degradation rapidly occurring in the birds' North American breeding grounds and their Latin American wintering grounds is indeed cause for concern. Fragmentation of temperate forests has been shown to negatively affect many migrant species by exposing them to higher predation pressure and cowbird nest parasitism (Hagan and Johnston 1992, Askins et al. 1990). Additionally, the restricted winter ranges of most neotropical migrants, mainly confined to eastern Central America and the Caribbean, translate into higher concentrations of birds per unit area. Thus, loss of specific tropical habitats may affect relatively large proportions of whole populations (Hagan and Johnston 1992, Keast and Morton 1980). The threats to neotropical migrants during the breeding and wintering seasons reflect seasonal changes in vulnerability; but breeding and wintering constitute no more than two- thirds of a migrant's life. The migratory period also poses great ecological, behavioral, and physiological challenges to birds (Kaiser 1992, Winker et al. 1992a, Moore and Yong 1991, Gill 1990). Risks during migration are great. Birds that travel hundreds or thousands of kilometers need to rest and refuel. During these stop-overs, migrants must be able to overcome the obstacles of new and unknown habitats and unpredictable resources (e.g. food and cover) while maintaining or increasing fat reserves and avoiding predators. An understanding of this phase is also critical to comprehensive conservation efforts on behalf of migratory landbirds. Yet the ecology of migration remains inadequately studied and its relevance to conservation is only beginning to be recognized (Moore et al. in press). Migratory landbirds employ a variety of migration strategies. The timing, routes and distances of migratory flight may differ from species to species and even from individual to individual (Gauthreaux 1982). During the spring and fall, migrants can be seen all over North America. There are, however, sites known to experience predictably heavy visitation by migrants. These stop-over concentration areas are generally related to major physiographic elements such as large peninsulas, bays, lakes, mountains, or ecological 1 barriers (e.g. the Gulf of Mexico). Two factors combine to make stop-over concentration sites both ecologically interesting and critical to conservation. First, high densities of migrants increase the potential for direct and indirect competition and increase the relative importance of all available resources (Winker et al. 1992b, Moore and Yong 1991). It follows that loss of resources through human manipulation of the environment could affect a large proportion of the entire population. Second, the majority of the concentration sites in North America are found in coastal areas that are experiencing the fastest human population growth on the continent. In this report we present an overview and results of the first phase of a two-year ecological study of fall migrants at a known stop-over concentration site on the lower Delmarva Peninsula (Northampton County, Virginia). STUDY BACKGROUND AND JUSTIFICATION Bounded by the Chesapeake Bay to the west and undeveloped Atlantic barrier islands to the east, the lower Delmarva Peninsula has long been recognized as a significant stop-over area for migrating birds of all kinds (Rusling 1936). This area is included in the Western Hemisphere Shorebird Reserve Network and is home to the Kiptopeke songbird banding and hawk observation station established by the Virginia Society of Ornithology 29 years ago. Giving further confirmation of the ecological value of the lower Delmarva for fall migrants, the U.S. Fish and Wildlife Service established the Eastern Shore National Wildlife Refuge at the peninsula tip specifically for the conservation of migratory birds. Unlike the Cape May Peninsula to the north, intensive study of fall migrants on the lower Delmarva did not begin until 1991. A regional study of the geographic distribution of fall migrants on the Cape May and Delmarva peninsulas was initiated in that year (Mabey et al. in prep.). While some general regional patterns of migrant abundance were identified in that study, local landscape and habitat associations were obscured by the study's large scale geographic approach. Stop-over concentrations on the lower Delmarva differ from other coastal concentration areas such as the northern Gulf Coast and the Cape May Peninsula for at least two reasons. First, neotropical migrants that stop on the Delmarva do not appear to face any immediate major ecological barriers that would necessitate extremely long non-stop flights. 2 Second, relatively more short-distance migrants (those birds that winter in southern U.S.) appear to use the Delmarva as a stop-over site than use the Cape May peninsula or the Gulf Coast (P. Kerlinger pers. comm., M. Woodrey pers. comm.). Although this is likely to be a result of simple geography, the large numbers of short distance migrants add a unique dimension to stop-over ecology on the lower Delmarva. The presence of short-distance migrants increases the overall ecological value of Eastern Shore habitat and may provide more potential prey for raptor species. Interactions between short- and long-distance migrants during stop-over has never been thoroughly addressed (Winker et al. 1992b). Further studies of stop-over ecology on the lower Delmarva will not only be important to a broader understanding of migration but will play a significant role in Northampton County's conservation initiatives. With the adoption of their comprehensive plan in 1990, Northampton officially recognized the value of the area's unique natural resources as the current and historical base of the county's economy andculture (Northampton County Joint Local Planning Commission 1990). Agriculture is the county's leading industry; in 1987, the county's 119 commercial farms generated $43,085,703 (Northampton Co. Planning and Zoning Dept. 1989). Shell and finfishing are also critical to the local economy, representing an estimated 10-20% of Virginia's bay region industry. In 1988, the bay region brought in $62,096,849 worth of seafood. Forestry has the potential for being the third most important economic base in the county but provided only $500,000 directly to the community in 1988, although the estimated "value" of timber sales for that year is over fourteen million dollars (Northampton Co. Planning and Zoning Dept. 1989). There is also growth potential the nature- and historic-based tourism. Land use patterns in Northampton County have remained relatively stable over the past century. In 1986 about 35% of land area was in cropland, 20% in forest, 39% in marsh/wetland, and only 5 % was classified as urban, industrial, or other (Northampton Co. Planning and Zoning Dept. 1989). Agricultural lands do not appear to be increasing because the best soils are already in cultivation. Forestlands are decreasing slowly as they are transferred into "alternate uses", mostly home sites. Rapid change in the landscape is, however, on the horizon. In eleven miles of bayside shoreline from the tip of the peninsula north, almost seven have already been subdivided for development. The majority of this land is forested and may be one of the most important areas for migrating landbirds on the entire Delmarva Peninsula (Mabey et al. in prep.). Northampton County will face a radical population shift as vacation and retirement homes are built over the next 5-10 years. 3 In keeping w ith the Northampton County comprehensive plan's commitment to managed growth, a Special Area Management Plan (SAMP) was initiated in 1992 with funding from the National Oceanic and Atmospheric Administration's (NOAA) Office of Coastal Resource Management. In the context of the SAMP, Northampton County has acknowledged migratory landbirds and their habitats to be of significant conservation value. By including neotropical migrants as a resource to protect and enhance through new, enforceable policies, Northampton County is recognizing the international importance of the Delmarva Peninsula as a stop-over concentration area as well as the integral role birds and their habitat play in the ecological health of the region. The SAMP seek s to control the cumulative and secondary impacts of coastal development by "maintaining maximum vegetation cover for wildlife habitat and nutrient removal from non-point runoff' and by steering development away from "sensitive wildlife habitat and groundwater recharge areas and toward areas with greatest carrying capacity" (Virginia Coastal Resources Management Program: Coastal Zone Management Act Section 309 Final Strategy, VACOE, Grant No. NA170ZO359-01). The SAMP effort will also be directed toward increasing public access and promoting appropriate nature tourism for the area. To achieve its goals, Northampton County has identified the need for detailed scientific data that will classify sensitive wildlife areas and assess the value of native vegetation in relation to wildlife. The continuing project introduced here has been designed to fill that need. 4 PROJECT OBJECTIVES The overriding objective of our study is to determine distribution patterns and habitat associations of migrant landbirds on the lower Delmarva Peninsula. The strength and scope of many of the SAMP's policy goals will rest on answers to the following questions: 1. Are there any geographically defined concentrations of migrants within the lower Delmarva and where are they? 2. On a habitat level, what are the characteristics of forested areas (native vegetation) that are strongly associated with fall migrants? 3. Is there any biologically significant interaction between geographic and vegetation factors that are relevant to policy development? OVERVIEW OF FIELD DESIGN Study Area The first research phase of this two-year project was conducted over an eleven week period from August 17 through October 30, 1992 on the lower Delmarva Peninsula (Northampton County, Virginia; Figure 1). The study area is confined to the mainland portion of the county from Eastville-Indiantown (Lat. 37' 21') south to the tip of the peninsula (Lat. 37" 07'). Forest Patch Inventory In order to determine the feasibility of various design options, an inventory of all forested patches within the study area was conducted in June of 1992. Infrared, aerial photographs (1:24000 scale) were used to delineate existing forest patches. A full-scale mylar overlay of forest patches was produced from photographs and reductions were produced from this image (reduced image shown in Figure 2). Each patch was individually coded and its area determined using an electromagnetic digitizing tablet. The maximum and minimum distance of each patch was then measured to the bayside, the seaside, and to the peninsula tip. All forest patches were then visited individually over a two-day period to determine forest type (pine, hardwood, mixed), approximate forest age (clearcut to mature), apparent understory density, residential status, and ease of access. 5 I I I I I I I I Figure 1: Map of Delmarva Peninsula, study area indicated in black. Study area extends 20 km from the tip of the peninsula to Cherrystone Inlet. I I I I I I 'I I I I I Dalmovs pelansula j Study Location to 5 0 to SCALE. a. Figure I I I I I I I I Figure 2: Configuration of forested patches (indicated in black) within the study area. Non- forested area is primarily agricultural land. I I I I I I I I I I I DISTRIBUTION OF FOREST PATCHES (Within Study Area) q6w r dt Figure 2 7 Over 250 forested patches were delineated within the study area (this does not include prominent forest bands near the tip on seaside and bayside margins). Over 85% of forest patches were less than 20 ha in size. In addition, greater than 90% of the forested acreage in the management area was pine dominated or pine/hardwood mix. Most patches were of cutting age (majority > 40 years old) and only 4 clearcuts were found over the entire area. The lack of variation in patch size, age class and forest type clearly limited opportunities to conclusively address particular habitat parameters. In fact, results from the inventory suggested that only pine or pine/hardwood patches are available in the quantities needed to complete a full design and those only in two size classes (4 - 8 ha and 9 - 13 ha). Conceptual Design In terms of the broad range of objectives (geographic patterns needed for zoning ordinances, bird/vegetation relationships needed for vegetation ordinances), the spatial scales of concern range from individual layers of vegetation to the entire management area. Meeting the information needs of these objectives requires a design capable of collecting and integrating data over a broad area but with a fine level of resolution. In addition to examining distribution patterns over the two focal scales (geographic, vegetation-level), we identified a series of intermediate scales relevant to the ultimate policy objectives of Northampton County's SAMP. We examined distribution patterns within 4 nested scales: 1) within vegetational strata, 2) within forest patches, 3) between forest patches, and 4) between geographic areas. Experimental units were balanced both within and between spatial levels using a hieratchical experimental design. This approach allows for the assessment of spatial patterns within a given scale and the simultaneous integration of patterns between scales. This was accomplished using a single type of information gathering unit designed to resolve distribution differences at the finest scale and then aggregating these units to reveal information over broader scales (Figure 3). Design finplementation The sample units were 30 m fixed-radius plots. Survey plots were not two- dimensional, but rather cylinders extending from ground level up through the forest canopy. All birds detected were identified to species and placed in 2 m intervals up to 8 m (an 8 in height corresponds to the vertical limit of the vegetation measuring technique used, see below). Birds detected above 8 m were placed either in the canopy proper or in the remaining subcanopy depending on their vertical position (Figure 4). Six survey plots were 8 I I I I I I I I Figure 3: Conceptual model of nested design illustrating the four spatial scales included in I study. I I I I I I I I a M Scaling Distribution JI- . . ........ Geographic Between Patch Within Patch % % Figure 3 Vegetational Strata I I I I I I I I I Figure 4: Illustration of cylindrical survey plot. Layers represent forest strata assigned to I all birds detected. I I I I I I I - I I I Diagram of Survey Plot Canopy Subcanopy 8M 6m 4' rn 2m Figure 4 arranged along a "survey route" for all forest patches included in the study. In order to examine the distribution of birds within forest patches, the six survey plots were divided evenly between "edge" plots (survey plots with centers 30 m from edges such that plot edges were tangent to the forest edge) and "interior" plots (survey plots with centers positioned away from patch edges), (Figure 5). Although there were many patch characteristics of interest, the forest patch inventory established that patch size was the most promising. Only two patch sizes were common and had a broad enough distribution to be included in the study. Twenty-four forest patches were chosen within the study area that were categorized as small (4 - 8 ha; 12 patches) or large (9 13 ha; 12 patches). As much as possible, forest type and age were controlled across the study area. To examine broad-scale distribution patterns, the study area was divided into 6 "geographic zones" (Figure 6). Boundaries for these zones were established at 5 Ian intervals moving up the peninsula from the tip and the two upper zones where the peninsula widens were split down the center. Two spatial replicates of both small and large forest patches were chosen for study within each geographic zone (Figure 7). This approach allows us to detect true patch size and geographic patterns. In summary, this design allows for the assessment of several different levels of spatial variation using a hierarchy of nested information. Birds detected are placed within vertical strata in points that are located either on patch edges or interiors, but occur within large or small patches that in turn are located within some larger geographic area. ZZ M I .1 I I I I I I Figure 5: Example patch map illustrating survey route, experimental plots, compass bearings, and dimensions. I I I I I I I I I I I 0 n NNithin.-Patct, DistributIO of we ID&w 12 I I I I I I I I Figure 6: Delineation of six geographic zones within the study area. Zone boundaries are I set at 5 kin intervals from the peninsula tip. I I I I I I I I I I I I LOCATION OF SIX GEOGRAPHIC ZONES i I 1 5 6 1 1 0@ I 11 3 4 i I I 1 2 1 1 11 1 t@', I Figure 6 1 - 13 Figure 7: Illustration of geographic design indicating spatial replicates of small and large patches within zones. Configuration allows for separation of patch size and geographic effects. I I Between-Patch Distribution I I I - a FWW I I I 11 0 m I I I 1 0 m I I ffi@ I W I I Figure 7 1 14 Additional Investigations To strengthen the geographic design, two additional investigations were conducted. As may be seen in Figure 2, Zones I and 2 have prominent forest corridors along their bay and seaside margins. The habitat along the bayside has long been recognized as an important corridor for reverse morning flight and is the focus of most development currently planned for the lower peninsula. In order to investigate the relative importance of the bayside habitats, six survey routes each containing 6 survey plots were located both within the bayside and the seaside corridors. During the course of the forest inventory, 6 forest patches were located that were greater than 20 ha in size. Access to 4 of these "big" patches was obtained and they were used to investigate possible patch-size effects that may not be detected within the limited range of patch sizes used in the geographic design. Two 6-point routes were established within each of the 4 big patches. FIELD METHODOLOGY Field work was conducted within lower Northampton County between 1 August and 31 October 1992. Initial site establishment and setup was completed for all patches by 15 August. Scaled field maps were produced from 1:24000 scale aerial photographs for all forest patches included in the study. Within each patch map, survey routes were drawn with three survey plots tangential to the forest edge (edge plots) and three plots > 60 ni from the edge (interior plots), except in the few cases where the geometry of a patch was prohibitive. Plot centers were separated by a minimum of 75 m. Compass bearings and route dimensions were indicated on field maps to be used during setup (see Figure 5). Survey routes were established on the ground by using a compass for direction and pacing off transect dimensions. Routes were marked using colored flagging tape and plot centers were indicated with individually numbered wire flags. Plot perimeters were delineated with colored flagging tape for reference during surveys. Surveys of experimental plots were conducted 4 d/wk between 17 August and 30 October. Because of the spatial and temporal dynamics of migration, it was essential that all patches for a given design be surveyed as close in time as possible. This practice reduced the influence of day to day changes in bird abundance on observed distribution patterns. Forest patches were divided into two groups: 1) patches included in the geographic design (24 survey routes), and 2) Bay/seaside forested corridors and big patches (20 survey routes). 15 Group 1 and 2 patches were surveyed on separate days such that each was surveyed 2 d/wk in an alternating fashion. For survey purposes, patches within each group were subdivided into 6 subgroups. Six field observers were used to survey patches and patch subgroups were ordered in rounds (rounds are equivalent to 6 field days); each observer surveyed each patch during a round. This was done to gain maximum dispersion of observer bias. All patches for a given day were surveyed once in the morning and again in the afternoon (i.e. an observer surveyed a set of patches in the morning and the same set later that day). Morning surveys began 0.5 hr after sunrise and were concluded within 4 hr. Afternoon surveys were timed to be completed at least 0.5 hr before sunset. The,survey order of patches within subgroups was randomly determined to reduce the impact of time of day on distribution patterns. Surveys were not conducted during heavy winds or rain, however, we were able to complete all planned morning surveys (22 surveys/plot) and missed only 4 - 6 afternoon surveys (16 - 18 surveys/plot). During each visit to a forest patch, observers walked along survey routes until reaching numbered survey plots. All experimental plots were quietly searched for a 5-min period and all birds detected were recorded within appropriate strata. Aural identification was allowed for resident species only. No playbacks or pishes were used because they inflate surveys within fixed areas, result in species-specific biases, and make placement of birds within strata invalid. We quantified the vegetational characteristics of each study plot (N = 264) by measuring vegetation volumes at 20 points within each plot. We measured vegetation in the first eight meters above the ground using the pole method described by Mills et al. (1989). This method records all vegetation within a series of 0. 1 in radius cylindrical volumes centered around a pole marked into 0. 1 and 0. 5 in sections. At each of 20 points, we recorded the number of 0. 1 in volumes in half meter layers above the ground that contained vegetation, and identified the plant in each case. Dead vegetation was noted separately. Data collected in this manner can be used to generate indices of total vegetation volume, volume in each half meter layer, and volumes of each plant species or floristic category. RESULTS During the course of the 11-week study period nearly 10,800 point counts were conducted within forest patches. Surveys resulted in the detection of over 22,500 birds, 16 representant 119 species. Greater than 98% of the birds detected were identified to species. Remaining individuals could not be positively identified due to unavoidable circumstances (e.g. visual obstructions, poor visibility conditions, movement of birds away from the observer). All observations with positive identifications have been separated into five dependent variable groups: 1. All birds and species 2. Resident birds 3. Short-distance migrants 4. Long-distance migrants 5. Individual species with greater than 70 observations in the field. For the purposes of this study, resident species are those that have stable, year-round populations in our study area. Short-distance migrants are those species that generally do not migrate south of North America and may have both breeding and wintering populations in our study area. Long-distance migrants spend the winter in tropical and subtropical America, generally south of the United States, and may have breeding populations in our study area. (See Appendix I for a complete list of species and their classifications.) We have attempted to classify these species based on ecological factors. It is, therefore, important to note that not all species fit cleanly into these groups. Some species (e.g. Yellow-rumped or Pine Warbler) have extensive winter ranges that stretch from Virginia to sub-tropical America while others (e.g. Blue Jay) may have resident individuals and short- distance migrants wintering within our study area. Of the three bird categories used, long-distance migrants were the most diverse (62 species, 52.1 % of total) followed by short-distance migrants 31, 26.0%) and permanent residents (26, 21.8%). However, in terms of overall abundance, just the opposite pattern was observed. Permanent residents accounted for nearly half of all individuals detected (10,805, 48.6%) followed by short-distance (7,998, 36.0%) and long-distance migrants (3,416, 15.4%). Within individual migration categories, as well as for the entire species list as a whole, species were not equally abundant. All three bird categories were numerically dominated by relatively few species (see Figure 8 for species abundance curves). For example, 80% of the short-distance migrants were accounted for by only 4 species (including Blue Jay, Yellow-ramped Warbler, American Robin, and Golden-crowned Kinglet). Similarly, Carolina Wrens, Carolina Chickadees, Common Grackles, and Northern Cardinals combined represented over 70% of the resident birds detected. For long-distance migrants, the 17 Figure 8: Species abundance curves for resident, short-distance migrants, and long-distance migrants. Percent indicates the relative proportion of total observations accounted for by each species. Species rank is an ordering of the species within each group based on their absolute abundance (ordered from highest to lowest abundance). SPECIES ABUNDANCE CURVES 30 -fEF- Resident Short-distance -0- Long-distance 20 0 10 0 0 10 20 30 40 50 60 70 Species Rank Figure 8 18 American Redstart was by far the most abundant species observed, representing nearly one quarter of the entire category. Abundance patterns were used to select a representative subset of species for further analysis. All migrant species were included in subsequent analysis if they were detected 70 times or more. In addition, those resident species that were detected 70 times and were believed to be relatively sedentary were also included (see Appendix I). Those species that were relatively common but tend to move over large areas in flocks during the fall (e.g. Common Grackles, American Crows) were excluded. What follows is a series of temporal and spatial analyses of the three general migration groups and those individual species that were detected with enough frequency to stand alone. Temporal Patterns Seasonal -- The frequency of detection for all bird groups and many of the individual species varied with season. Figure 9 illustrates the seasonal patterns in species richness and abundance for individual groups. If we split the field season into an early (weeks 1 - 6) and late period (weeks 7 - 11), all of the bird groups exhibit a significant seasonal patterns in detection frequency (all G-statistics > 200, P < 0.001). For the two migration groups, the patterns indicate that long-distance migrants tend to move through the study area early in the season, followed by short-distance migrants somewhat later in the fall. Nearly 95 % of the short-distance migrants were detected after week 7 as compared to less than 25 % for long- distance migrants. As with long-distance migrants, resident species were detected significantly more often in the early period compared to the late period. We believe that this pattern reflects a seasonal change in detectability (due to changes in activity levels) rather than a reduction in overall abundance. Most of the individual species showed seasonal patterns similar to those of their respective groups. However, some exceptions did occur. Figures 10 - 12 present a general overview of seasonal patterns for selected species. All of the resident species were detected significantly more often during the early period (defined as above) than expected based on the number of surveys (all chi-squared statistics > 14.3, P < 0.001) except Red-bellied Woodpeckers. Red-bellied Woodpeckers were observed with significantly greater frequency during the late period (chi-squared statistic > 200, P < 0.001). All of the short-distance migrants were detected comparatively more often during the late period (all chi-squared statistics > 95, P < 0.001) with five of nine species having no observations during the early period. Seven of nine species of long-distance migrants were detected significantly more 19 Figure 9: Seasonal patterns in species richness and overall abundance for residents, short- distance migrants, and long-distance migrants. Percent indicates the relative proportion of total observations (for the entire field season) for each group accounted for during a given week. Week one is the third week of August and week 11 is the last week of October. Seasonal Patterns in Species Richness 80 70 Resident 60 -Short Distance Long Distance .2 so 40 - se 30 20 10 1 2 3 4 5 6 7 8 9 10 11 Week Seasonal Patterns in Abundance 50 40 E 3 0 20 10 0 1 2 3 4 5 6 7 8 9 10 11 Week Figure 9 20 Figures 10 - 12: Seasonal patterns in detection rates for selected resident, short-distance migrants, and long-distance migrants. Percent indicates the relative proportion of total observations accounted for by a given week. Week one is the third week of August and week 11 is the last week of October. -Seasonal Patterns in Detection Frequency For Selected Resident Species 30 Red-bellied 15 0 1 3 4 5 6 7 8 9 10 11 16 12 Chickadee 8 4 1 2 3 4 5 6 7 8 9 10 11 20 Titmouse 10 0 1 2 3 4 5 8 7 8 9 10 11 16 12 8 Carolina Wren 4 1 2 3 4 5 6 7 8 9 10 11 16 12 a Cardinal 4 0 1 2 3 4 5 6 7 8 9 10 11 Figure 10 21 Seasonal Patterns in Detection Frequency For Selected Short-distance Migrants 30- 20- Flicker 10- 0 7 1 6 4 5 6 7 8 9 10 11 Week 30- Blue Jay 20- 10- 0 1 2 3 4 5 6 7 8 9 10 11 Week 40 Winter Wren 20 0 2 3 4 5 6 7 8 9 10 11 70 Week G-c Kinglet 35 0 1 2 3 4 5 6 7 8 9 10 11 Week 90 45 Herm Thrush 1 1 2 3 4 5 6 7 8 9 10 11 Week go Robin 45 0 1 2 3 4 5 6 7 8 9 10 11 Week 50 25 Towhee 1 2 3 4 5 6 7 8 9 10 11 Week 40 Y-r Warbler 20 0 1 2 3 4 5 6 7 8 9 10 11 Week so Wth Sparrow 0 40 1 2 3 4 5 6 7 8 9 10 11 Figure 11 Week 22 Seasonal Patterns in Detection Frequency For selected Long-distance Migrants 30- 20- Y-b Cuckoo 10- 1 2 3 4 5 8 7 8 9 10 11 50- Week 25 Gnatcatcher 1 2 3 4 5 6 7 8 9 10 11 30- Week 20- Catbird -10 1 2 3 4 5 6 7 8 9 10 11 Week 40- 2.07 R-e Vireo 0 1 2 3 4 5 6 7 8 9 10 11 Week 40- 20 B&W Warbler 0 1 2 3 4 5 6 7' 8 9@ 10 1-1 Week 30- Bl-th-Bl 20- Warbler 10 0 1 2 3 4 5 8 7 8 9 10 11 Week 30 15 Pine Warbler 0 1 2 3 4 5 6 7 8 9 10 11 Week 30- 20- Ovenbird 10 0 1 2 3 4 5 6 7 8 9 10 11 Week 30- is7 Redstart - 0 Figure 12 1 2 3 4 5 6 7 8 9 10 ii 23 Week often during the early period (all chi-squared statistics > 46, P < 0.001) with only Black- throated -blue Warblers and Gray Catbirds moving through later in the season (both chi- squared statistics > 70, P < 0.001). An accounting of seasonal patterns for all species detected is presented in Appendix IL Daily -- Despite a very strong morning bias in detection frequency for all three bird groups, none of the groups exhibited a significant time of day pattern (Table 1). This result is due to the high degree of site to site variation in detection frequency. In other words, although more birds were detected in the morning for all sites, the total number of birds detected varied considerably between patches. Although 20 of 23 species were detected with higher frequency in the morning rather than afternoon survey periods, time of day had a statistically significant influence on relatively few of the species (see Table 1). Carolina Chickadee, Blue Jay, Golden-crowned Kinglet, Yellow-billed Cuckoo, and Pine Warbler showed a significant morning bias with Northern Flicker, Yellow-rumped Warbler, and Gray Catbird having notable trends. Carolina Wrens and Northern Cardinals showed a significant afternoon bias in detection frequency. Spatial Patterns Geographic Pattems -- All three of the general bird groups showed distribution patterns on a geographic scale that were significantly different from that expected by chance (all chi- squared statistics > 90, P < 0.001), (see Figure 13). Both short- and long-distance migrants, as a whole, seemed to be concentrated within 10 km of the peninsula tip with relatively fewer birds detected with increasing distance away from the tip. This distribution pattern is consistent with the idea that migrants of both types are using habitats near the tip of the peninsula before crossing the mouth of the Chesapeake Bay. Resident birds, as a group, showed the opposite distribution and reached their highest densities in those areas farthest from the tip. A clear explanation of their tip-avoidance pattern is not readily apparent except that forested habitats with the lower, narrow portion of the peninsula may be of poor quality due to low soil moisture and frequent salt spray. 24 Table 1: Comparisons between morning and afternoon survey, for bird groups and selected species. Data for stand, within the six geographic zones only were used in analysis. Morning Afternoon Bird Group X + S.E. X + S.E. F P Resident Red-bellied 7.0 + 1.27 5.2+ 0.93 1.36 NS Chickadee 32.2 + 2.22 20.3 + 1.63 21.97 <0.001 Carolina Wren 15.8 + 3.23 25.6 + 1.89 34.72 <0.001 Cardinal 9.6 + 1.96 10.4 + 1.51 10.03 <0.01 Richness 10.8 + 0.34 9.6+ 0.35 0.32 NS Abundance 173.3 + 17.47 111.8 + 16.51 0.17 NS Short-distance Flicker 11.3 + 2.23 6.6+ 1.43 3.10 0.05 < <0. 1 Blue Jay 31.3 + 3.25 19.8 + 3.10 6.51 <0.05 Winter Wren 1.2 + 0.35 0.8+ 0.24 0.94 NS G-c Kinglet 22.1 + 2.80 13.5 + 2.39 5.49 <0.05 Hermit Thrush 2.3 + 0.48 1.3+ 0.58 1.91 NS American Robin 16.5 + 5.24 28.4 + 8.06 1.53 NS Y-r Warbler 28.8 + 8.75 13.0 + 2.84 2.92 0.05 < <0.1 R-s Towhee 1.0 + 0.27 0.8+ 0.26 0.11 NS Wh-th Sparrow 2.9 + 1.04 2.7+ 0.94 0.02 NS Richness 10.1 + 0.60 8.9+ 0.52 0.01 NS Abundance 120.4 + 14,52 97.5 + 9.25 0.56 NS Long-"tance Y-b Cuckoo 0.8 + 0.16 0.2+ 0.09 4.36 < 0.05 Gnatcatcher 0.6 + 0.26 0.7+ 0.28 0.05 NS Gray Catbird 4.0 + 1.03 2.0+ 0.48 2.97 0.05 < <0. 1 Red-eyed Vireo 2.8 + 0.55 1.2+ 0.27 7.10 < 0.05 BI&Wh Warbler 4.9 + 0.77 4.0+ 0.73 0.56 NS BI-Ih-bl Warbler 2.2 + 0.40 1.5+ 0.32 1.98 NS Pine Warbler 6.7 + 1.41 3.3+ 0.79 4.47 <0.05 Ovenbird 1.5 + 0.32 1.0+ 0.16 1.66 NS American Redstart 13.0 + 3.41 8.8+ 2.18 1.26 NS Richness 14.9 + 1.28 11.0 + 0.60 1.05 NS Abundance 48.6 + 7.40 30.3 + 3.78 0.277 NS 25 Figure 13: Geographic patterns for resident, short-distance migrants, and long-distance migrants. Percentage values indicate the relative proportion of birds within the entire study area that were accounted for by particular regions. The symbols *** beside group names indicate significance to the 0.001 level for Chi-squared statistics comparing observed distribution patterns with an expected even distribution. Geographic Patterns for Bird Groups Resident Short-distance Long-distance Key to Color Codes for Geographic Maps M@--W-1 0-10% 20-30% 40-50% >50% 10-20% ....... 30-40% Figure 13 26 With relatively few exceptions, distribution patterns for the individual species examined were in agreement with their respective groups. All of the resident species were either evenly distributed across the study area (as was the case for Red-bellied Woodpeckers) or were skewed away from the tip (Figure 14). Most of the short-distance migrant species were concentrated near the tip with the notable exception of Golden-crowned Kinglets and Hermit Thrush that were distributed away from the tip and White-throated Sparrows that were evenly distributed (Figure 15). All of the long-distance migrants except Ovenbirds and Pine Warblers were concentrated near the tip (Figure 16). Both these exceptions were detected most frequently in the center of the study area. With only one notable exception, none of the selected species exhibited an interaction between geographic distribution and time of day. This result indicates that very little directional redistribution occurred after the initiation of morning surveys. This is an important result that suggest that most migrants have reached their stop-over habitats by 7:00 AM and that morning surveys after this time give reasonable reflections of habitat utilization patterns. The result also suggest that the time of day effect discussed earlier is primarily caused by changes in activity levels (and related detection rates) rather than significant, within-day movements out of the study area. The Golden-crowned Kinglet was the only species that appeared to relocate throughout the day. This species showed a significant time of day effect, a significant distribution away from the tip, and a time of day by geographic distribution interaction. By examining the relative distribution of kinglets observed during the morning and afternoon survey periods, there appears to be a net redistribution of birds to the north. The combination of these distribution patterns seems to suggest the kinglets are moving to the north in the early morning (before 7:00 AM) and that they are continuing this movement later into the morning when compared to the other migrants. Within the forested corridors along the edge of the peninsula, all three bird groups had significantly higher detection frequencies within the bayside plots (all chi-squared statistics > 100, P < 0.001)., Long-distance migrants, as a whole, had the largest bias with nearly 65 % detected along the bayside. Individual species exhibited all possible patterns but of the species with significant patterns, 75 % were detected more frequently along the bayside (including Red-bellied Woodpeckers, Blue Jays, Chickadees, Titmice, Golden-crowned Kinglets, Robins, Black-and-white Warblers, Black-throated-blue Warblers, and Redstarts). Robins showed the greatest bias with over 95 % of the individuals detected along the bayside. 27 Figures 14 - 16: Geographic patterns for selected species. Percentage values indicate the relative proportion of birds within the entire study area that were accounted for by particular regions. Significance values (generated from Chi-square tests) are given by symbols located beside species names: no symbol indicates no significant difference from expected, (*) indicates significance to the 0.05 level, (**) indicates significance to the 0.01 level, and indicates significance to the 0.001 level. Geographic Patterns for Selected Resident Species Red-bellied Chickadee Titmouse 7z .. . .... ..... . Car. Wren Cardinal Figure 14 28 Geographic Patterns for Selected Short-distance Migrants Flicker Blue Jay Win. Wren . . ....... . .......... G-c Kinglet Herm't Thr. Robin Y-r Warbler Towhee Wh-th Sparrow ..... ..... .......... ........... ..... ..... ... ....... ............ ............. Figure 15 29 04 Geographic Patterns for Selected Long-distance Migrants Y-b Cuckoo Gnatcatcher Catbird .......... .... .. . .. . Red-e Vireo B&W Warbler Bl-th-bl Warb. . ......... . . .... ..... .. . ... .. . ..... . Pine Warbler Ovenbird Redstart .......... Figure 16 30 Some notable species also showed a significant bias for the seaside corridor (including Yellow-billed Cuckoos and Yellow-rumped Warblers). Influence of Patch Size -- Within the relatively narrow range of patch sizes examined, patch size was not a significant determinant of patch use for any of the three bird groups (Table 2). Species richness and overall abundance was not influenced by patch size. Similarly, although many of the selected species exhibited a positive or negative trend in abundance with increasing patch size, relatively few patterns were statistically significant. Red-bellied Woodpeckers, Yellow-billed Cuckoos, and Red-eyed Vireos were the exceptions to this rule. These three species were detected with higher frequencies in larger forest patches when compared to smaller patches. This pattern suggest that the use of a given forest patch for these species is area-dependent. However, the biological significance of this pattern during migration remains unclear. Distribution within Patches -- The location of census plots in relation to the edge or interior of forest patches had a significant influence on the number of species and individuals detected (Table 3). Overall, bird abundance and species richness were significantly higher within census plots that were positioned along patch edges. This pattern, along with the observation that many of the birds were detected directly along the edge, suggests that patch edges accounted for a disproportionate number of the total birds detected. Consistent with the overall patterns of abundance, many of the selected species exhibited a significant edge/interior bias in distribution. All but two of these species were detected with higher frequency along patch edges and many were over twice as common there. Only Carolina Wrens and Black-throated-blue Warblers showed notable distributions away from patch edges. In uence of Vegetation Density -- In order to examine the influence of vegetation density on Ifl space use, vegetation measurements were surnmed within the four 2 in vertical strata for each census point. Summary data for all four strata were then run through a principal component analysis to determine the dominant source of variation (in vegetation density) across all census plots. The PCA defined two distinct sources of variation including: 1) meters 0 - 4 hereafter referred to as understory, and 2) meters 4 - 8 hereafter referred to as subcanopy (Table 4). For this reason, the following analyses focus on vegetation data summarized for the understory and subcanopy categories. 31 Table 2: Descriptive statistics and results of one-way analysis of variance between small, medium, and large forest patches. Sample sizes = 12, 12, and 8 for small, medium, and large patches respectively. Small Medium Large Bird Group X + S.E. X + S.E. X + S.E. F P Resident Red-bellied 5.2 + 1.94 8.8 + 1.55 12.3 + 1.42 3.86 < 0.05 Chickadee 33.0+ 2.46 33.4 + 3.61 34.5 + 3.98 0.04 NS Carolina Wren 43.2+ 4.02 52.1 + 4.88 48.6 + 6.47 0.92 NS Cardinal 17.8+ 3.08 18.6 + 2.56 11.6 + 3.02 1.45 NS Richness 11.0+ 0.58 10.6 + 0.38 10.8 + 0.56 0.19 NS Abundance 170.3 + 26.00 176.3 + 24.53 126.5 + 18.91 1.03 NS Short-distance Flicker 9.8 + 3.29 12.7 + 3.10 17.3 + 3.30 1.16 NS Blue Jay 32.7+ 5.80 29.8 + 3.20 19.6 + 3.33 1.94 NS Winter Wren 1.0 + 0.51 1.3 + 0.51 1.9 + 0.74 0.54 NS G-c Kinglet 23.3+ 4.44 20.9 + 3.58 17.9 + 2.72 0.44 NS Hermit Thrush 2.1 + 0.75 2.5 + 0.62 1.3 + 0.25 2.91 NS Am. Robin 18.2+ 7.65 14.8 + 7.47 8.5 + 6.26 0.38 NS Y-r Warbler 32.3+ 9.94 25.2 + 14.80 25.8 + 6.69 0.12 NS R-s Towhee 1.1 + 0.43 0.8 + 0.32 0.5 + 0.33 0.53 NS Wh-th Sparrow 2.0 + 1.04 3.8 + 1.82 0.9 + 0.35 1.05 NS Richness 10.0+ 1.07 10.2 + 0.60 8.5 + 0.50 1.04 NS Abundance 121.5 + 23.33 119.3 + 18.35 93.5 + 9.98 0.52 NS Long-distance Y-b Cuckoo 0.2 + 0.17 1.0 + 0.21 1.1 + 0.40 4.64 < 0.05 Gray Catbird 4.3 + 1.66 3.8 + 1.30 2.5 + 0.89 0.35 NS Red-eyed Vireo 1.3 + 0.43 4.3 + 0.82 4.6 + 1.30 4.99 <0.05 .BI&Wh Warbler 4.4 + 0.87 5.2 + 1.31 7.9 + 3.18 0.98 NS BlThBl Warbler 1.7 + 0.53 2.8 + 0.57 1.8 + 0.41 1.36 NS Pine Warbler 5.7 + 1.93 7.8 + 2.10 5.1 + 1.97 0.46 NS Ovenbird 1.3 + 0.31 1.6 + 0.57 1.6 + 0.48 0.12 NS Am. Redstart 14.5+ 6.39 11.6 + 2.71 9.6 + 3.48 0.25 NS Richness 14.2+ 2.32 15.6 + 1.17 11.6 + 1.21 1.13 NS Abundance 45.6 + 14.04 51.6 + 5.48 46.0 + 9.71 0.11 NS 32 Table 1: Results ol Mann-Whitney U comparisons between edge and interior points, Sample sizes 121 and 115 for edge and interior points respectively. Edge Interior Bird Group X + S.E. X + S.E. U P Resident Red-bellied 2.88 + 0.256 2.27 + 0.204 9095 NS Chickadee 8.89 + 0.527 8.42 + 0.506 9095 NS Carolina Wren 7.28 + 0.641 8.67 + 0.481 12698 < 0.00 1 Cardinal 5.50 + 0.446 2.49 + 0.247 12350 <0.001 Short-distance Flicker 2.87 + 0.325 2.27 + 0.208 9267 NS Blue Jay 8.59 + 0.727 5.43 + 0.427 11099 <0.001 Winter Wren 0.49 + 0.080 0.31 + 0.168 10345 <0.001 G-c Kinglet 4.78 + 0.435 5.35 + 0.560 8777 NS Hermit Thrush 0.55 + 0.117 0.44 + 0.098 9231 NS Am. Robin 6.29 + 1.258 4.23 + 1.077 10085 <0.05 Y-r Warbler 8.68 + 1.403 4.80 + 0.840 10405 <0.01 R-s Towhee 0.41 + 0.092 0.12 + 0.035 9615 <0.05 Wh-thr Sparrow 1.39 + 0.375 0.02 + 0.17 10889 <0.001 Long-distance Y-b Cuckoo 0.24 + 0.044 0.30 + 0.057 8453 NS Gnatcatcher 0.26 + 0.063 0.36 + 0.094 8864 NS Gray Catbird 1.46 + 0.278 0.48 + 0.096 10788 <0.001 Red-eyed Vireo 0.81 + 0.101 0.66 + 0.089 9345 NS BI&Wh Warbler 1.85 + 0.237 1.39 + 0.165 9840 0.05 < <0. I BlThBl Warbler 0.52 + 0.085 0.070 + 1.393 7815 0.05 < <0. 1 Pine Warbler 1.80 + 0.318 1.42 + 0.154 8463 NS Ovenbird 0.51 + 0.067 0.34 + 0.051 9612 0.05 < < 0. 1 Am. Redstart 3.63 + 0.758 2.53 + 0.259 9136 NS Total Richness 19.50 + 0.510 16.42 + 0.346 11573 < 0.00 1 Total Abundance 102.83 + 7.152 68.83 + 2.842 11765 <0.001 33 Table 4: Results of principal components analysis of six forest strata categories for vegetation volume. Forest Strata Eigenvalue Percent of Variation Cumulative Percent Category I - 4 m 3.36985 56.2 56.2 4 - 8 m 1.69332 28.2 84.4 1 - 2 m 0.62787 10.5 94.9 2 - 4 m 0.29121 4.9 99.7 4 - 6 m 0.01554 0.3 100.0 6 - 8 m 0.00222 0.0 100.0 34 Across the set of census plots, vegetation density within both the understory and subcanopy varied by several fold. The overall density of vegetation was considerably higher in the understory compared to the subcanopy, however, vegetation density was skewed to low values for both strata. In order to examine the availability of vegetation conditions, the range of variation for both strata was subdivided into 10 discrete categories. A frequency distribution of census plots based on vegetation density was then generated for both the understory and subcanopy (Figure 17). These distributions indicate the number of points surveyed that fall within a given vegetation range and were used as the null distribution in testing for bird/vegetation relationships. In order to evaluate how vegetation density influenced plot use, the number of observations of selected species were summed for each plot and tested against the expected distribution based on the vegetation categories. Figures 18 - 20 illustrate the patterns in deviations between the observed and expected use of understory values. Most of the selected species examined exhibited significant deviations from expected distribution patterns based on both the understory and subcanopy densities. However, deviation patterns were generally more easily interpreted with regards to the understory density. For residents, all but one species under-utilized plots with relatively low density understories and over-utilized areas with high density understories. This same general pattern was observed for both groups of migrants. Although a few species showed significant deviations that were not easily interpreted, only the Tufted Titmouse, Hermit Thrush, and Yellow-billed Cuckoo appeared to prefer areas with relatively low understory density. These general patterns seem to suggest that most species are selecting areas based on the characteristics of understory vegetation and that most species prefer areas where vegetation is relatively dense. In comparison to the understory patterns, many of the species examined do not appear to be as selective for subcanopy characteristics (Figuies 21 - 23). Many of the deviation patterns do not lend themselves to clear interpretation. However, some notable patterns were observed. Cardinals, Flickers, Blue Jays, Robins, Black-and-white Warblers, Pine Warblers, and Redstarts all seem to prefer high density vegetation in the subcanopy. Redstarts in particular showed a high preference for plots with relatively dense subcanopies. As with the understory vegetation, Tufted Titmice and Yellow-billed Cuckoos appear to prefer low density areas. 35 A Figure 17: Frequency distribution for census plots across the observed range of density for understory and subcanopy vegetation. Understory refers to the area from ground level to a height of 4 m. Subcanopy refers to the area from 4 to 8 meters above the ground. Density categories presented indicate the midpoint for a range of density values. Density values indicate the sum of vegetation measurements within the understory and subcanopy for each census plot. Vegetation Density within Understory 20 CO) a 0 0- 0 10 - cr P U- Im 0 No 23 43 63 83 103 123 143 163 183 203 Vegetation Density Vegetation Density within Subcanopy 30 0 CL 20 CD cr LL- 10 CD 0 19 35 51 67 83 99 115 131 147 187 Vegetation Density A Figure 17 36 j Figures 18 - 20: Deviation patterns for selected resident, short-distance migrants, and long- distance migrants. Bars indicate the difference between bird utilization patterns and those expected based on the availability of census points within a given range of understory density. Negative values indicate that points within the given vegetation range were underutilized relative to their availability. Positive values indicate that points within the given vegetation range were overutilized relative to their availability. Significance values (generated from Chi-square tests) are given by symbols located beside species names: no symbol indicates no significant difference from expected, (*) indicates significance to the 0.05 level, indicates signficance to the 0.01 level, and indicates significance to the 0.001 level. Space-use Across an Understory Gradient For Selected Resident Species 3 2 0 Red-bell. -2 -3 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 2 0 Chickadee -4 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 10 0 Titmouse -10 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 4 Car. Wren -2 -5 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 10 Cardinal -10 1 2 3 4 5 6 7 8 9 10 Figure 18 Vegetation Gradient 37 Space-use Across an UnderstorV,. Gradient For Selected Short-distance Migrants 10 - 0 Flicker *** -10 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 4 2 0 Blue Jay -2 -4 1 2 3 4 5 6 7 8 9 10 25 Vegetation Gradient 10 Win. Wren -5 20 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 3 0 G-c Kinglet -3 -6 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 10 0- Hermit Thr. -10 - 1 2 3 4 5 6 7 a 9 10 Vegetation Gradient 20 - 10 - Robin 0 _= -10 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 10 0 Y-r. Warbler -10 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient Towhee -15 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 20 10 NO 0 Wh-th Spar. -10 -20- 1 2 3 4 5 8 7 8 9 10 Figure 19 Vegetation Gradient 38 Space-use Across an Understgr _y Gradient or Selected Long-distance Migrants 2- 0 Y-b Cuckoo -2 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 20- 10- Gnatcatcher. *** -10 -20 1 2 3 4 5 6 '7 8 9 10 20 Vegetation Gradient 10 Catbird 0 -10-1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 10- 0 Red-9 Virso -10 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 3 B&W Warb. -1 NOW- -3 1 2 3 4 5 6 7 8 9 10 10 Vegetation Gradient BfThBl Warb. -10 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 3 -1 Pine Warb. -5 -9 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 6 4 2 Ovenbird -2 -4 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 20 10 Redstart 0 A -10 1 2 3 4 5 6 7 a 9 10 Figure 20 Vegetational Gradient A 39 Figures 21 - 23: Deviation patterns for selected resident, short-distance migrants, and long- distance migrants. Bars indicate the difference between bird utilization patterns and those expected based on the availability of census points within a given range of subcanopy density (refer to Figure 17). Negative values indicate that points within the given vegetation range were underutilized relative to their availability. Positive values indicate that points within the given vegetation range were overutilized relative to their availability. Significance values (generated from Chi-squared tests) are given by symbols located beside species names: no symbol indicates no significant difference from expected, (*) indicates significance to the 0.05 level, (**) indicates significance to the 0.01 level, and (***) indicates signficance to the 0. 00 1 level. Space-use Across a Subcanopy Gradient For Selected Resident Species 5 3 Red-bell -3 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient Chickadee 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 4 2 0 Titmouse -2 -4 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 3 2 0 Car. Wren -2 3 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient Cardinal 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient Figure 21 40 Srce@use Across a Subcanopy Gradient or elected Short-distance Migrants 10 - Y-b Cuckoo 0 -10 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 10 0 Gnatcatcher -10 -20 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 20 10 Catbird 0 -10 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient Red-* VIreo 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 4 2 MML - B&W Warb. 0 -2 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient BIThBI Warb. 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 8 4 JIL Pine Warb. 0 -4 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient Ovenbird 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 20 - 10 - Redstart 0 -10 -1 2 3 4 5 6 7 8 9 10 Figure 22 41 Vegetation Gradient Sirce se Across a SubcanopaGradient or @u elected Long-distance grants 3 2- 0 Flicker -27 -3 -_ 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 3 Blue Jay -3 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 20- 10- Win. Wren 0 -10 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 4 2 G-c Kinglet 0 -2 4 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient Hermit Thr. 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 20 10 Robin 0 -101 2 3 4 5 6 7 8 9 10 Vegetation Gradient 6 M 3 0 Y-r Warbler -3 1 2 3 4 5 6 7 8 9 10 Vegetation Gradient 10 0 Towhee -10 -20 1 2 3 4 5 6 7 8 9 10 20- Vegetation Gradient 10- 0 Wh-th Spar. -10 Figure 23 20 1 2 3 4 5 6 7 8 9 10 42 Vegetation Gradient Pattems in Strata Use -- All of the selected species showed significant patterns in the use of vertical strata (Figures 24 - 26). Although intergrades do exist, species generally fall into four groups. These groups include: 1) canopy species, 2) subcanopy species, 3) understory species, and 4) ground species. The majority of the species would be considered subcanopy or understory species with relatively few being restricted to either the canopy or the ground. In general, strata use complements the patterns observed in vegetation associations. Most of the species that primarily use the understory or ground are found in plots containing high density understory vegetation. Likewise, many of the species that utilize the subcanopy seem to prefer areas with dense vegetation in the subcanopy. 43 Figures 24 - 26: Relative use of vertical strata by selected resident, short-distance migrants, and long-distance migrants. Strata categories included are as follows: 1 indicates 0 - 2 m above ground, 2 indicates 2 - 4 m above ground, 3 indicates 4 - 6 in above ground, 4 indicates 6 - 8 m above the ground, 5 indicates remaining subcanopy above 8 m, and 6 indicates the forest canopy. Significance values represent the results of Chi-square tests comparing observed strata use to an expected even distribution and are given by symbols located beside the species name: no symbol indicates no significant difference from expected, indicates significance to the 0.05 level, (**) indicates significance to the 0.01 level, and indicates signficance to the 0.001 level. Patterns in Vertical Distribution For Selected Resident Species Red-bell 6 5 cc ra 4 '70 .2 3 -M 2 '1@'2'0'3@'40 50 60 70 % of total Chickadee Titmouse cma 5 5 z Cd Cz 1"4 rh 7;-n3 3 2 2 0 10 20 30 % of total 0 10 20 30 40 % of total Car. Wren Cardinal 6 6- CO 5 Cd G 4 G 4 'a 3 co3 .2 -2 2 2 > 0 10 20 30 40 0 10 20 30 40 % of total % of total Figure 24 44 Patterns in Vertical Distribution For Selected Short-distance Migrants Flicker Blue Jay Win. Wren 5 CO 5- Z6 4 ZA4 c-A 4- 3 3- 2 2 2 0 il@ '20 30 40 50 102030405060 0 20 40 60 80 100 % of total % of total % of total Robin G-c Kinglet Hermit Thr. *** 6 6 5 2 5 2 5 Ca CO 4 4 4 3 3 ;52 CD2 2 0 10 20 30 0 10 20 30 40 50 0 10 20 30 % of total % of total % of total Y-r Warbler Towhee Wh-thr Sparrow 6 6- 6- 5- z! 5-1 2 5 Ca 2 W-:= 4- 4 3 @V3 3 2 2 2 FMMM 1 0 10 ' 26 ' 30 0 20 40 60 80 020 40 60 80 % of total % of total % of total Figure 25 45 Patterns in Vertical Distribution For Selected Loing-distance Migrants Y-b Cuckoo Gnatcatcher 'Catbird 6 6 6 5 2 5 25 ca Cd 4 C/3 4 3 3 3 2 2 2 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 50 60 % of total % of total % of total Red-e Vireo 131 & Wh Warb. Bl-th-bl Warb. 6 5 6 6 cc5 5 co4 cc 4 4 -23 c 3 ' c,3 2 'i 2 2 I F I I 0 10 20 30 40 0 10 20 30 40 0 10 '20 30 40 % of total % of total % of total Pine Warbler Ovenbird Redstart 6 6 - 6 cc5 m 5 5 4 4 4 ca 3-1 -Fa3 2 - 2 2 CD 010 20 30'4'0'510 0 15 30 45 60 75'9@ 0 10 26 '36 '4'0 % of total % of total % of total Figure 26 46 DISCUSSION Seasonal patterns of abundance were quite clear for all three groups of species. Neotropical migrants were more abundant during the first half of the migration season than they were later. Short-distance migrants display the opposite pattern. In fact, although our data indicate that we adequately covered peak movement periods for long-distance migrants, this was not the case for short-distance migrants. This result suggests that it will be necessary to continue sampling through mid-November in order to thoroughly incorporate the heaviest periods of movement for this group in our study. Detection of residents peaked late in the first half of the Study period and then tapered off. This is likely due to dispersal of young and post-breeding behavioral changes that decrease the detectability of resident birds. These temporal patterns have important implication for planning tourism events around migration. A second year of data that covers the entire migration period will add to the reliability of predicting the peaks of fall migration. On a geographic scale, we found that there was a trend towards highest abundances of both long- and short-distance migrants close to the peninsula tip. In contrast, residents tended to have the reverse distribution with their lowest densities close to the peninsula tip. Migrants were also found to be more abundant on the bayside of the peninsula while residents were more evenly distributed. These geographic distribution patterns will be fundamental to the SAMP's goal of directing further development away from sensitive wildlife areas. The development of zoning ordinances to protect native vegetation would also be facilitated by the delineation of areas with heaviest bird use in lower Northampton County. We will investigate these patterns further in the coming field season so that they can be more fully defined. Within the parameters of our study, the size of a woodlot did not appear to have any strong relationship to the abundance of any of the bird groups or most individual species. Yellow-billed Cuckoo, Red-eyed Vireo, and Red-bellied Woodpecker all seemed to respond positively to larger woodlots and showed significant differences in abundance from small to large to big patches. The fragmented character of the lower Delmarva's landscape and the relatively similar size of all woodlots in the area may explain this result. It is possible that below a certain size, birds do not react to differences in forest area. An alternative hypothesis is that fores area alone is not as meaningful a parameter for most birds during migration as it appears to be during the breeding season. 47 Within forest patches, more birds were counted at edge plots than interior plots. Further, we found that most species were under-represented in plots with low density vegetation and appeared to be selecting for those plots with high density vegetation. Vegetation density differs between edge and interior plots only within the first two meters of the ground (Strata 1) where it is significantly higher for edge plots. Within plots, however, most species analyzed demonstrated strata associations that correspond to their known breeding and wintering behavior. These results will play an integral role in creating meaningful vegetation ordinances and Memoranda of Understanding (MOUs) between Northampton County and the Virginia Department of Transportation or power companies. After the completion of the study, results such as these will be shared with the public so that they may be incorporated into land management decisions of private citizens. The future direction of this study will be guided by the results of the first year. Two principal themes will be pursued in the coming field season: a continuation of the current emphasis on spatial and temporal distributions and an investigation of possible underlying causes of these distributional patterns. Although the imprtance of testing the resilience of the patterns identified in the first year should not be overlooked, the second field season will also allow us to move to a fmer geographic scale. For example, observations suggest that migrant concentrations on the bayside of the lower Delmarva may be a "veneer" phenomenon, occurring only within a thin section of woodlands directly adjacent to the coast. Detailed resolution of the distribution of fall migrants within the concentration areas of the bayside and peninsula tip will be highly beneficial to land use planning efforts. Also of value to long-term planning for the protection of migrants and their habitats is an understanding of why the birds stop over on the lower Delmarva and what they need from these habitats. Obviously, the fall scope of those questions is beyond the constraints of this study. However, data from the first year indicate that the relative importance of the lower Delmarva varies among species. Some species (i.e. American Redstart and Golden-crowned Kinglet) are extremely common in the area and are likely to be using the area for longer stop-overs than other species. We will address this further in the coming field season, focusing primarily on habitat use. 48 ACKNOWLEDGEMENTS Funding for this study was provided through grant # NA170ZO359-01 from NOAA's Office of Coastal Resource Management and administered by the Virginia Department of Environmental Quality's Coastal Resources Management Program. This study would not have been possible without the support and hard work of numerous individuals and agencies. We thank Melissa Donoff, Peter Leimgruber, Debbie Orr, Sharon Torgersen, and Sean Smith for assistance in the field and Georgia Kratimenos and Daryl Thomas for both field assistance and help with the graphics. Thomas Smith and Karen Terwilliger assisted with management responsibilities. Toni Harrison, Pat Jarrell, and Faye McKinney provided critical administrative support. We appreciate the private landowners of Northampton County who generously gave us permission to work in their woodlots; Dr. George Oertel and the Oceanography Department of Old Dominion University for use of the Oyster Field Station; Sherman Stairs, Eastern Shore National Wildlife Refuge for access to refuge property; the staff of The Nature Conservancy's Virginia Coast Reserve for logistical support; and the Northampton County Planning Office for technical assistance. 49 LITERATURE CITED Askins, R. A., J. F. Lynch, and R. Greenberg. 1990. Population declines in migratory birds in eastern North America. Current Ornithology 7:1-57. Gauthreaux, S. A. 1982. Ecology and evolution of migration systems. Avian Biology 6:93- 168. Gill, F. B. 199o. Ornithology. Pp. 243-258. W. H. Freeman and Company, New York. Hagan, J. M. and D. W. Johnston. 1992. Ecology and conservation of Neotropical migrant landbirds. Smithsonian Institution Press, Washington, D.C. Hill, N. P. and J. M. Hagan, 111. 1991. Population trends of some northeastern North American landbirds: A half-century of data. Wilson Bull. 103:165-182. Kaiser, A. 1992. Fat deposition and theoretical flight range of small autumn migrants in southern Germany. Bird Study 39:96-110. Keast, A. and E. S. Morton. 1980. Migrant birds in the Neotropics: Ecology, behavior, and conservation. Smithsonian Institution Press, Washington, D.C. Mills, G. S., J. B. Dunning, Jr., and J. M. Bates. 1991. The relationship between breeding bird density and vegetation volume. Wilson Bull. 103:468-479. Moore, F. R. and W. Yong. 1991. Evidence of food-based competition among passerine migrants during stopover. Behavioral Ecology and Sociobiology. 85-90. Moore, F. R., S. A. Gauthreaux, Jr., P. Kerlinger, and T. R. Simons. In press. Stopover habitat: Management implications and guidelines in Proceedings: Status and management of neotropical migratory landbirds. (D. Finch and P. Stangel, eds.). Rocky Mountain Forest and Range Station General Technical Report. Fort Collins, CO. 50 Robbins, C. S., J. R. Sauer, R. S. Greenberg, and S. Droege. 1989. Population declines in North American birds that migrate to the neotropies. Proc. Natl. Acad. Sci. 86:7658-7662 Rusling, W. J. 1936. The study of the habits of diurnal migrants, as related to weather and land masses during the fall migration on the Atlantic Coast, with particular reference to the hawk flights of the Cape Charles (Virginia) region. Unpubl. report. Winker, K., D. W. Warner, and A. R. Weisbrod. 1992a. The Northern Waterthrush and Swainson's Thrush as transients at a temperate inland stopover site. Pp 384- 402 in Ecology and conservation of Neotropical migrant landbirds (J. M. Hagan and D. W. Johnston, Eds.). Smithsonian Institution Press, Washington, D.C. Winker, K., D. W. Warner, and A. R. Weisbrod. 1992b. Daily mass gains among woodland migrants at an inland stopover site. Auk 109:853-826. 51 0 Appendix I: List of species detected, their scientific names, and bird category in which they were placed. Bird categories are as follows: 1) permanent resident, 2) short-distance migrant, 3) long-distance migrant. Category Common Name Scientific Name 1 2 3 Green-backed Heron Butorides Striatus x American Woodcock Scolopax Minor x Common Bobwhite Colinus virginianus x Sharp-shinned Hawk Accipiter striatus x Cooper's Hawk Accipiter cooperi x Red-tailed Hawk Buteo jamaicensis x Broad-winged Hawk Buteo platypterus x Bald Eagle Haliaeetus leucocephalis x Osprey Pandion haliaetus x Turkey Vulture Cathartes aura x Black Vulture Coragyps atratus x American Kestrel Falco sparverius x Merlin Falco columbarius x Northern Harrier Circus cuaneus x Great-horned Owl Bubo virginianus x Mourning Dove Zenaida macroura x Yellow-billed Cuckoo Coccyzus americanus x Black-billed Cuckoo Coccyzus erythropthalmus x Chuck-will's Widow Caprimulgus carolinensis x Ruby-throated Hummingbird Archilocus colubris x Belted Kingfisher Ceryle alcyon x Red-headed Woodpecker Melanerpes erythrocephalus x Red-bellied Woodpecker Melanerpes carolinus x Yellow-bellied Sapsucker Sphyrapicus varius x Downy Woodpecker Picoides pubescens x Hairy Woodpecker Picoides cillosus x Pileated Woodpecker Dryocopus pileatus x Northern Flicker Colaptes auratus x Eastern Wood Pewee Contopus virens x Acadian Flycatcher Empidonax virescens x Great-crested Flycatcher Myiarchus crinitus x Least Flycatcher Empidonax minimus x Yellow-bellied Flycatcher Empidonax flaviventris x Eastern Phoebe Sayornis phoebe x Eastern Kingbird Tyrannus tyrannus x Tree Swallow Tachycineta bicolor x Blue Jay Cyanocitta cristata x American Crow Corvus brachyrhynchos x Fish Crow Corvus ossifragus x Carolina Chickadee Parus carolinensis x Brown Creeper Certhia amercana x Tufted Titmouse Parus Bicolor x 52 Appendix I: ---- continued---- White-breasted Nuthatch Sitta carolinensis X Red-breasted Nuthatch Sitta canadensis X Brown-headed Nuthatch Sitta pusilla X House Wren Troglodytes aedon X Winter Wren Troglodytes troglodytes X Carolina Wren Thryothorus ludovicianus x Ruby-crowned Kinglet Regulus calendula X Golden-crowned Kinglet Regulus satrapa X Blue-gray Gnatcatcher Polioptila caerulea X Eastern Bluebird Sialia sialis X Wood Thrush Hylocichla mustelina X Swainson's Thrush Catharus ustulatas X Gray-cheeked Thrush Catharus minimus X Hermit Thrush Catharus guttata X Veery Catharus fuscescens X American Robin Turdus migratorius X Gray Catbird Dumetella carolinensis X Mockingbird Mimus Polyglottis X Brown Thrasher Toxostoma rufum. X Cedar Waxwing Bombycilla cedrorum X Eastern Meadowlark Sternella magna X European Starling Sturnus vulgaris X White-eyed Vireo Vireo griseus X Solitary Vireo Vireo solitarius X Red-eyed Vireo Vireo solivaceus X Warbling Vireo Vireo gilvus X Philadelphia Virec, Vireo philadelphicus X Blue-winged Warbler Vermivora Pinus X Golden-winged Warbler Vermivora chrysoptera X Tennessee Warbler Vermivora peregrina X Nashville Warbler Vermivora ruficapilla X Northern Parula Parula americana X Black-and-white Warbler Mniotilta varia X Black-throated Blue Warbler Dendroica caerulescens X Cerulean Warbler Dendroica cerulea X Blackburnian Warbler Dendroica fusca X Chestnut-sided Warbler Dendroica pensylvanica X Cape May Warbler Dendroica tigrina X Magnolia Warbler Dendroica magnolia X Yellow-rumped Warbler Dendroica coronata X Black-throated Greed Warbler Dendroica virens X Yellow-throated Warbler Dendroica dominica X Prairie Warbler Dendroica discolor X Bay-breasted Warbler Dendroica castanea X Blackpoll Warbler Dendroica striata X Pine Warbler Dendroica pinus X Palm Warbler Dendroica palmarum. X Mourning Warbler Oporornis philadelphia X 53 Appendix I: ---- continued---- Connecticut Warbler Oporornis agila X Kentucky Warbler Oporornis formosus X Canada Warbler Wilsonia canadensis X Wilson's Warbler Wilsonia pusilla X Worm-eating Warbler Helmitheros vermivorus X Ovenbird Seiurus aurocapillus X Louisiana Waterthrush Seiurus motacilla X Northern Waterthrush Seiurus noveboracensis X Common Yellowthroat Geothlypis trichas X Yellow-breasted Chat Icteria virens X American Redstart Setophaga ruticilla X Blue Grosbeak Guiraca caerulea X Rose-breasted Grosbeak Pheucticus melanocephalus X Northern Cardinal Cardinalis cardinalis X Indigo Bunting Passerina cyanea X Rufous-sided Towhee Pipilo erythrophthalmus X Song Sparrow Melospiza melodia X Field Sparrow Spizella Pusilla X Chipping Sparrow Spizella passerina X White-throated Sparrow Zonotrichia albicolis X White-crowned Sparrow Zonotrichia leucophrys X Swamp Sparrow Melospiza georgiana X Savannah Sparrow Passerculus sandwichensis X Dark-eyed Junco Junco hyemalis X Red-winged Blackbird Agelaius Phoeniceus X Brown-headed Cowbird Molothrus ater X Common Grackle Ouiscalus quiscula X Orchard Oriole Icterus spurius X Northern Oriole Icterus galbula X Scarlet Tanager Piranga olivacea X Summer Tanager Piranga rubra X American Goldfinch Carduelis tristis X 54 Appendix 11 Weekly summary of species detected. Numbers indicate total number of individuals detected (standardized number detected) Numbers were standardized as follows: (total individuals detected/Total survey routes completed) X 10. SPECIES Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8 Week 9 Week 10 Week 11 Total Green-backed Heron l(0.07) 1 American Woodcock 4(0.26) 11(0.63) 15 Common Bobwhite 1(0.06) 5(O.28) 1(0.06) 3(0.17) 2(0.12) 12 Sharp-skinmed Hawk 4(0.23) l(O.06) l(0.07) 5(O.45) 4(0.23) 2(0.13) 5(0.28) 22 Cooper's Hawk 1(0.06) 2(0.18) 1(O.07) 1(0.06) 5 Redtailed Hawk 2(0.11) 3(0.17) 3(0.19) 2(0.12) 2(0.13) 3(0.17) 15 Broad-winged Hawk 1(0.06) 1(0.06) 1(0.06) 1(0.06) 4 Bald Eagle 1(0.06) 1 Osprey 1(O.06) 1 Turkey Vulture 2(0.11) 1(0.06) 1(0.07) 4(0.23) 8 Black Vulture l(O.06) 1 American Kestral 1(0.06) 1(0.06) 2(0.11) 4 Merlin 2(0.11) 2 Northam Harrier 1(0.06) 1 Great-horned Owl 2(0.11) 3(.017) 1(0.06) 4(0.23) 1(0.06) 1(0.07) 1(0.09) l(0.07) 14 Mourning Dove 6(0.34) 18(1.02) 20(l.14) 25(1.42) 9(0.51) 15(O.96) 11(0.73) 11(0.98) 23(1.34) 56(3.68) 20(1.14) 214 Yellow-billed Cuckoo 1O(O.57) 19(1.08) 16(0.91) 13(0.74) 5(O.28) 5(O.32) 1(0.07) 1(0.09) 1(0.06) 1(0.06) 72 Black-billed Cuckoo 1(0.06) 1(0.06) 2 Chuck-will's Widow 2(0.11) 2(0.11) 4(0.23) 1(0.06) 3(0.17) 12 Ruby-throated Hummingbird 13(0.74) 13(0.74) 8(045) 6(0.34) 1(0.06) 1(0.06) 42 Belted Kingfisher 1(0.06) 1 Red-headed Woodpecker 14(0.80) 11(0.63) 18(1.02) 28(l.59) 8(0.45) 8(0.51) 4(0.26) 3(0.27) 4(0.23) 7(0.46) 18(1.02) 123 Red-bellied Woodpecker 12(0.68) 35(1.99) 28(l.59) 37(2.10) 27(l.53) 43(2.76) 45(2.98) 73(6.52) 134(7.79) 104(6.84) 142(8.07) 680 Yellow-bellied Sapsucker 1(0.06) 5(0.45) 9(0.52) 1(0.07) 6(0.34) 22 Downy Woodpecker 5O(2.84) 43(2.44) 57(3.24) 59(3.35) 42(2.39) 20(1.28) 13(0.86) 15(1.34) 34(l.98) 13(0.86) 24(1.36) 370 Hairy Woodpecker 2(0.11) 3(0.17) 6(0.34) 1(0.06) 5(O.28) 3(0.19) 3(0.20) 4(0.36) 2(0.12) 3(0.20) 3(0.17) 35 Pileated Woodpecker 5(O.28) 1(0.06) 1(0.06) 11(0.63) 2(0.13) 7(0.46) 5(O.45) 4(0.23) 1(0.07) 1(0.07) 38 Northam Flicker 11(0.63) 32(1.82) 7(0.40) 26(1.48) 24(1.36) 66(4.23) 78(5.17) 138(12.32) 119(6.92) 81 (5.33) 95(5.40) 677 Eastern Wood Powee 7(0.40) 9(0.51) 2(0.11) 3(0.17) 1(0.06) 2(0.13) 5(O.45) 6(0.35) 35 Acadian Flycatcher 2(0.11) 3(0.17) 3(0.17) 8 Great-crested Flycatcher 2(0.11) 5(O.28) 3(0.17) 7(0.40) 4(0.23) 2(0.18) 1(0.06) 24 Least Flycatcher 1(0.09) 1(0.06) 2 Yellow-bellied Flycatcher 3(0.17) 6(0.35) 9 Eastern Phoebe 1(0.06) 3(0.17) 1(0.06) 1(0.06) 1(0.06) 7(0.46) 12(1.07) 6(0.35) 18(1.18) 13(0.74) 63 Eastern Kingbird 18(l.02) 4(0.23) 1(1.06) 1(0.06) 24 Tree Swallow 1(0.06) 2(0.13) 3 Blue Jay 9(0.51) 40(2.27) 17(0.97) 33(l.88) 35(1.99) 19(l.22) 28(1.85) 414(36.96) 523(30.41) 301(19.80) 428(24.32) 1847 American Crow 24(l.36) 76(4.32) 25(1.42) 52(2.95) 54(3.07) 60(3.85) 43(2.85) 22(1.96) 51(2.97) 40(2.63) 67(3.81) 514 Fish Crow 26(l.48) 30(l.70) 82(4.66) 102(5.80) 39(2.22) 18(1.15) 18(1.19) 1(0.09) 1(0.06) 7(0.46) 12(0.68) 336 Carolina Chickadee 289(16.42) 344(19.55) 280(15.91) 250(14.20) 178(10.11) 145(9.29) 145(9.60) 114(0.18) 180(10.47) 153(10.07) 205(11.65) 2283 Brown Creeper 60(0.40) 4(0.36) 7(0.41) 15(O.99) 25(0.99) 57 Tufted Titmouse 28(l.59) 25(1.42) 28(l.59) 41(2.33) 22(l.25) 33(2.12) 13(0.06) 13(1.16) 45(2.68) 5(O.33) 15(0.85) 268 White-breasted Nuthatch 1(0.06) 1(0.06) 2 Red-breasted Nuthatch 1(0.09) 1(0.06) 2(0.13) 4 Brown-headed Nuthatch 1(0.06) 1 Appendix II cont. SPECIES WEEK 1 WEEK 2 WEEK 3 WEEK 4 WEEK 5 WEEK 6 WEEK 7 WEEK 8 WEEK 9 WEEK 10 WEEK 11 TOTAL House Wren 1(0.06) 10(0.57) 7(0.45) 10(0.66) 3(0.27) 4(0.23) 3(0.20) 11(0.63) 49 Winter Wren 11(0.98) 8(0.47) 32(2.11) 30(1.70) 81 Carolina Wren 342(19.43) 470(26.70) 391(22.22) 399(22.67) 277(15.74) 177(11.35) 152(10.07) 174(15.54) 229(13.31) 160(10.53) 256(14.55) 3027 Ruby-crowned Kinglet 20(1.79) 25(1.45) 78(5.13) 18(1.02) 141 Golden-crowned Kinglet 3(0.20) 143(12.77) 128(7.44) 256(16.84) 810(46.02) 1340 Blue-gray Gnatcatcher 37(2.10) 16(0.91) 6(0.34) 14(0.80) 4(0.23) 1(0.06) 3(0.27) 81 Eastern Bluebird 1(0.06) 5(0.28) 6 Wood Thrush 2(0.11) 1(0.06) 1(0.06) 4(0.36) 6(0.35) 2(0.13) 16 Swalnson's Thrush 3(0.17) 1(0.06) 7(0.45) 1(0.07) 5(0.29) 2(0.13) 1(0.06) 20 Gray-cheeked Thrush 1(0.06) 1(0.06) 1(0.06) 1(0.07) 5(0.45) 8(0.47) 3(0.20) 1(0.06) 21 Hermit Thrush 1(0.09) 23(1.51) 108(6.14) 132 Veary 1(0.06) 1(0.06) 8(0.45) 19(1.08) 4(0.26) 1(0.06) 2(0.13) 37 American Robin 16(091) 36(2.05) 9(0.51) 5(0.28) 8(0.45) 4(0.26) 1(0.07) 10(0.58) 120(7.89) 1177(66.88) 1386 Gray Catbird 1(0.06) 2(0.11) 12(0.68) 14(0.90) 26(1.72) 69(6.16) 59(3.43) 38(2.50) 32(1.82) 253 Mockingbird 4(0.23) 3(0.17) 3(0.17) 2(0.11) 1(0.06) 1(0.07) 2(0.18) 1(0.06) 3(0.17) 20 Brown Thrasher 3(0.17) 7(0.40) 10(0.64) 2(0.13) 15(1.34) 7(0.41) 2(0.13) 1(0.06) 47 Cedar Waxwing 6(0.34) 2(0.11) 3(0.17) 3(0.17) 1(0.06) 4(0.26) 9(0.52) 8(0.53) 36 Eastern Meadowlark 1(0.06) 1 European Starling 66(3.75) 88(5.00) 60(3.41) 93(5.28) 3(0.17) 26(1.67) 17(1.13) 39(2.27) 35(2.30) 45(2.56) 472 White-eyed Vireo 4(0.23) 5(0.28) 4(0.23) 5(0.28) 2(0.11) 20 Solitary Vireo 1(0.06) 2(0.18) 8(0.47) 10(0.66) 4(0.23) 25 Red-eyed Vireo 29(1.65) 44(2.50) 59(3.35) 36(2.05) 13(0.74) 6(0.38) 6(0.40) 2(0.18) 1(0.06) 196 Warbling Vireo 1(0.06) 1 Philadelphia Vireo 8(0.45) 1(0.06) 2(0.06) 2(0.11) 4(0.26) 3(0.17) 20 Blue-winged Warbler 1(0.06) 3(0.17) 6(0.34) 2(0.11) 12 Golden-winged Warbler 1(0.06) 2(0.11) 3 Tennessee Warbler 2(0.13) 4(0.36) 6 Nashville Warbler 1(0.06) 1 Northern Parula 3(0.17) 13(0.83) 6(0.40) 4(0.36) 6(0.35) 32 Black-and-white Warbler 58(3.30) 102(5.80) 140(7.95) 43(2.44) 34(1.93) 29(1.86) 11(0.73) 4(0.36) 4(0.23) 2(0.13) 427 Black-throated Blue Warbler 2(0.11) 25(1.42) 32(2.05) 27(1.79) 12(1.07) 46(2.67) 13(0.86) 157 Cardean Warbler 3(0.17) 3 Blackburnlan Warbler 2(0.11) 1(0.06) 1(0.06) 4 Chestnut-sided Warbler 1(0.06) 1(0.07) 2 Cape May Warbler 1(0.06) 1(0.07) 2 Magnolla Warbler 1(0.06) 4(0.23) 2(0.11) 8(0.51) 2(0.13) 6(0.35) 23 Yellow rumped Warbler 12(1.07)594(34.53)619(40.72) 547(31.08) 1772 Black throated Green Warbler 1(0.06) 1(0.06) 1(0.06) 1(0.06) 3(0.20) 1(0.09) 5(0.29) 13 Yellow throated Warbler 3(0.17) 3(0.17) 3(0.17) 1(0.06) 1(0.06) 11 Prairie Warbler 2(0.11) 1(0.06) 1(0.06) 4 Bay-breasted Warbler 3(0.19) 2(0.18) 1(0.06) 6 Pine Warbler 44(2.50) 63(3.58) 114(6.48) 68(3.86) 36(2.05) 32(2.05) 32(2.05) 38(2.52) 15(1.34) 6(0.35) 4(0.26) 420 Palm Warbler 10(0.58) 3(0.20) 2(0.11) 15 Mourning Warbler 1(0.06) 1 Connecticut Warbler 1(0.06) 1(0.06) 2 Kentucky Warbler 1(0.06) 1(0.06) 2 Appendix II cont. SPECIES Week l Week 2 Week 3 Week 4 Week 5 Week6 Week 7 Week 8 Week 9 Week 10 Week 11 TOTAL Canada Warbler 2(0.11) 5(O.28) 1(0.06). Wilsons Warbler 1(0.06) 1(0.06) Wormating Warbler 8(0.45) 2(0.11) 4(0.23) 1(0.06) Ovnbd 4(0.23) S(0.28) 21(1.19) 10(0.57) 33(l.88) 20(l.28) 3(0.20) 9(0.80) 1(0.06) 5(O.33) Lulslan Wattrthrush 7(0.40) 1(0.06) 1(0.06) 1(0.06) Northern Waterthrush 6(0.34) 3(0.17) 9(0.51) 1(0.06) 4(0.23) 1(0.07) Common Yallowthroat 2(0.11) 4(0.23) S(O.28) 4(0.23) 9(0.51) 6(0.38) 4(0.26) 3(0.27) 5(0.29) 3(0.20) American Redstart 91 (S.17) 104(S.91) 180(10.23) 101 (5.74) 115(6.53) 99(6.35) 84(5.56) 19(l.70) 11 (0.64) 4(0.26) Blue Grosbeak 2(0.11) 4(0.23) 7(0.40) 48(1.2) Rosb ad Grosbeak 2(0.11) 2(0.13) Northern Cardinal 162(9.20) 161(9.15) 135(7.67) 115(6.53) 102(5.80) 71(4.55) 64(4.24) 48(l.29) 82(4.77) 5l (3.36) S7 Indigo Bunting 11 (0.63) 17(0.97) 1(0.06) 1 (0.06) Rufouded Towhee 1(0.06) 48(4.29) 9(0.S2) 34(2.24) 26 Sorg Sparrow 1 (0.06) 10(0.66) 48 Field Sparrow 12 Chipping Sparrow 1 (0.09) Whtthroated Sparrow 1 (0.07) 8(0.71) 43(2.83) 128 Whtrowrwd Sparrow 1 (0.07) 2 Swamp Sparrow 1 (0.06) 4(0.26) 29 Savannah Sparrow 1 (0.06) Darkyd junco 2(0.18) 2(0.13) 29 Redwinged Blackbird 2(0.11) 30(l.70) 12 Brownheaded Cowbird 1 (0.06) 20(1.14) 1 (0.06) 1 Common Grackle 263(14.94) 42(2.39) 123(6.99) 191 (10.8S) 220(12.50) 20 (1.28) 203 (13.44) 93(8.30) 16(0.93) 7(0.46) 068 Northam Oriole 3(0.17) 22(1.2S) S(OAS) 2(0.18) Scarlet Tanager 1(1.06) S(O.28) 1 (0.06) Summer Tanager 7(0.40) 14(0.80) 19(1.08) 2S(I.42) 2(0.11) American Goldfinch 1(0.06) 1 (0.06) UID Flycatcher 1 (0.06) 3(0.17) 2(0.11) 2(0.11) 5(O.32) 8(0.S3) 7(0.63) 1 (0.06) 3(0.20) UID Crow 9(0.51) 1 (0.06) 1 (0.06) 13(0.86) S(OAS) 3(0.17) S(O.33) .01 UID Thrush 1 (0.06) 1 (0.06) 1(0.06) 1 (0.06) 5(O.28) 10(0.64) 1 (0.07) 12(0.70) (O.S) S UID Mro 1 (0.06) 2(0.11) 1 (0.06) 1 (0.06) 1 (0.07) UID Warbler 4(0.23) 6(0.34) 15(O.SS) 3(0.17) 13(0.74) 45(2.88) 44(2.91) 4(0.36) 44(2.S6) IS(O.99) I UID Sparrow 3(0.20) 5(0.45) 3(0.20) 9 UID Tanager 2(0.11) UID Bird 12(0.68) 6(0.34) 5(O.28) 10(O.S7) 11 (0.63) 13(0.83) 50(3.31) 7(0.63) 17(0.99) IS(O.99) 22 UID Hawk S(O.28) 7(0.4S) 1 (0.07) 4(0.23) 01 UID Knlet 9(0.80) 010 UID Owl 2(0.11) 1 (0.07) 2(0.12) UID Acpiter 1 (0.06) UID Woodpecker 1 (0.06) 1 (0.06) 2(0.11) 1 (0.06) 3(0.19) 1 (0.06) UID Watrthrush 1 (0.06) 1 (0.06) J.. COASTAL SERVICES CTR LWRARY 1 3 6668 14111971 1 I I I i i I i I I I I i I I i I i i I