The Migratory Bird Research Group at the University of Southern Mississippi is working with the U.S. Army Engineer Research and Development Center (ERDC) on a long-term investigation of avian stopover habitat as identified through radar technology (“The Identification of Military Installations as Important Migratory Bird Stopover Sites and the Development of Bird Migration Forecast Models: A Radar Ornithology Approach”). Research for this project is being conducted in the Vernon Unit of the Calcasieu Ranger District of the Kisatchie National Forest, adjacent to Fort Polk, Louisiana. Forests types in the region can be categorized as predominately longleaf pine (Pinus palustris), hardwood, and mixed longleaf pine-hardwood.

RESEARCH ACTIVITY

Radar Component - Weather surveillance radar is a useful tool for the detection, monitoring and quantification of the movement of birds in the atmosphere. As such, radar is capable of addressing questions about broad geographic scale movements over various time scales. Over the course of a migration season, for example, radar provides an indication of where and how frequently migratory flights are made. The Clemson University Radar Ornithology Lab will use WSR-88D (weather surveillance radar – 1988 Doppler) radar in conjunction with GIS to delimit the amount of bird migration passing over Fort Polk and Kisatchie National Forest during spring and fall migration. Although weather surveillance radar can be used to determine areas where migrants stopover, it provides only a rough indication of density in relation to habitat type and little, if any, information on species, much less age, sex or energetic condition. Consequently, radar information is most valuable when integrated with data at the next [“on the ground”] level of analysis.

Census Component – During the peak of 2006 spring migration we quantified abundance and diversity of landbird migrants by means of surveying protocols. These data can be used to address daily and within-season patterns of migration. ERDC also conducted these surveys during fall migration of 2005. Similar surveys will be conducted during fall of 2006 and spring of 2007 across multiple habitat types.

Telemetry Component - At the local and habitat scale, radio-telemetry can be used to study the movement pattern of migrants in relation to landscape variables. For example, radio-telemetry can be used in conjunction with translocation experiments designed to test predictions about patch occupancy: How do migrants react to patch size, habitat boundaries, habitat type? Radio-telemetry also helps us to understand how migrants make decisions about habitat use during stopover. Radio-telemetry can provide insight into stopover duration, temporary home range size, and exploratory behavior of migrants, as well as whether the factors of habitat patch size and placement within the landscape also affect the availability and suitability of stopover habitat for birds.

Banding Component- During the peak of 2006 spring migration we used mist-nets to band migrants in hardwood, pine, and mixed pine-hardwood in Kisatchie National Forest. Presumably migrants select particular habitats to enhance their fitness. Although the effect of habitat use on fitness (i.e., survival and reproductive success) is difficult to estimate during migration, more immediate consequences of habitat use can be measured in relation to how well migrants satisfy energy demand and meet other exigencies that arise during stopover. Mist-nets were used to capture migrants in selected habitats to measure the energetic condition of migrating birds in relation to habitat. Despite radar indicating that there were large passages of migrants during the time we were banding, we did not catch many migrants after considerable effort during the spring of 2006. Because migrants may not be concentrated enough in any one area within this landscape, we plan to focus more on following individual birds using radio-tracking during 2007 spring migration.