Occupancy and Habitat Selection of Secretive Marsh Birds in the Western Arkansas River Valley
January 2009 - December 2010
- Arkansas Audubon Society
- University of Arkansas
- Arkansas Game & Fish Commission
Secretive marsh birds which include the King Rail (Rallus elegans), Virginia Rail (R. limicolor), Sora (Porzana carolina), American Bittern (Botaurus lentiginosus), Pied-billed Grebe (Podilymbus podiceps) and Common Moorhen (Gallinula chloropus) occupy wetlands throughout North America. Recent evidence suggests that most secretive marsh bird populations are in decline which is most strongly related to the decline of palustrine emergent wetlands in North America. Recently in Arkansas, surveys of habitat use by secretive marsh birds were assessed in the Delta, however, secretive marsh bird distribution, abundance and habitat use outside of the Delta is poorly understood. As well, the effects of management practices being used on publicly owned wetland units in the Arkansas River Valley are also poorly understood for marsh birds. In April-June 2009, we conducted surveys for marsh birds and collected habitat data on public lands along the western portion of the Arkansas River in Arkansas. We detected 136 marsh birds in our 24 survey points. The management areas where we detected marsh birds are those where the water was drawn down in the middle of the growing season (May-September) or those where the water was allowed to evaporate during the summer. The areas where the water was drawn down early in the growing season (January – April) had the fewest number of detections, except where the units contained pools of water that remained throughout the growing season; this was the case with Frog Bayou’s Unit 3. The areas surveyed in 2009 will be surveyed again in 2010. We will reposition a subset of our survey points to locations away from the levee. We will analyze the data using the program MARK to estimate probability of detection (p) and occupancy (ψ) of marsh birds in our study area and the habitat factors that affect occupancy.