Analysis of habitat use by intercontinental bird migrants along the northern Coast of the Gulf of Mexico

Objectives

Our project is designed to reflect the hierarchical nature of the migrant's relationship to habitat and to provide information at different spatial scales from gross patterns of habitat availability and use along the northern coast of the Gulf of Mexico to finer scale information on habitat suitability and consequences of en-route habitat use for migratory birds. The proposed project is well suited to a partnership funding effort. Interest in the project is widespread and several potential partners have been identified such as The Nature Conservancy; state agencies including The University of Southern Mississippi, Mississippi Department of Marine Resources, and the Mississippi Museum of Natural Sciences; federal agencies including NOAA, USDA Forest Service, and Fish & Wildlife Service; and industry, including International Paper. The objectives of this project are to (1) identify specific study areas, (2) secure agreement from federal, state and/or private agents to conduct research on their lands, and (3) explore funding opportunities from prospective partners.

Methodology

The project is organized into five, hierarchically ordered components which provide an increasing degree of resolution:

1. Map (GIS) Component (Simons and Pearson): Landsat satellites provide high resolution, scanned TM data areas of interest (e.g., coastal Mississippi between the Pearl River on the west and the Pascagoula on the east and permit us (a) to determine abundance and spatial pattern of habitat types can then be derived from a classification of landsat scenes of study area landscapes along the northern coast of the Gulf of Mexico and (b) to quantify historical trends in the availability of habitats used by landbirds during spring and fall migration.
2. Radar Component (Gauthreaux, Jr.,): Use weather surveillance radar (WSR-88D) to detect migrants in the atmosphere and to "map" the spatiotemporal pattern of arrival and departure along the northern coast of the Gulf of Mexico. Stopover areas are determined by the pattern of echoes from migrants as they depart from stopover areas shortly after dark. This information will be overlaid upon the map created in the Map Component. Although weather surveillance radar can be used to determine areas where migrants make landfall, radar provides only a rough indication of density in relation to habitat type and no information on species, much less age, sex or energetic condition. Consequently, radar information is most valuable when integrated with more refined levels of the analysis.
3. Telemetry Component (Moore and Simons): Virtually nothing is known about the movement of migrants between the time they arrive across a landscape and their departure. For example, arrival along the northern coast of the Gulf of Mexico in spring appears to be a broad front phenomenon, yet migrants are spatially more concentrated upon departure. Radio-telemetry is used to study the movement pattern of migrants in relation to spatial features of the landscape (e.g., number and size of patches of each habitat type).
4. Census Component (Moore and Simons): At a finer degree of resolution, migrants are sampled in different habitats and/or in relation to different spatial features of the stopover landscape according to a blockwise experimental design. This design permits us to (a) ground verify and describe habitats available to landbird migrants, and (b) quantify abundance, including daily and within-season patterns of diversity, of landbird migrants in different habitats (treatments) and in relation to different spatial features, and (c) draw strong inferences about migrant-habitat relations.
5. Behavioral Component (Moore and Simons): Evaluate the consequences of the migrant-habitat relationship by (a) observing how individual migrants use habitat (e.g., foraging behavior) and (b) capturing migrants in different habitats, which will allow quantification of energetic status, rates of mass change and length of stay.

Data derived from the Radar, Telemetry, Census and Behavioral Components will be analyzed against the spatial context provided by the regional habitat map (Map/GIS Component). Dynamic spatial modeling (e.g., Window Analysis and individual-based Models) will combine information on migrant stopover ecology (e.g., habitat preferences, energetic condition and flight ranges) with habitat data to simulate how patterns of habitat availability (patch size, shape and distribution) may affect migratory bird populations. Spatial models will yield testable predictions about how spatial features might affect habitat suitability, create migratory corridors, or serve as ecological 'traps' for migrants.