Northern Prairie Wildlife Research Center
Monica Ross, Richard O. Flamm, Bradley L. Weigle, Florida Department of Environmental Protection, Florida Marine Research Institute, 100 Eighth Avenue S.E., St. Petersburg, FL 33701 USA
The Florida Department of Environmental Protection's radio-telemetry project tagged 27 female manatees (Trichechus manatus latirostris) between 1991 and 1996. Travel paths for female manatees with calves and those without calves were compared for differences in distance traveled along the west coast of Florida and for differences in habitat use within Tampa Bay. Satellite telemetry data and visual observations were entered into a Geographic Information System (GIS). GIS-based programs connected sequential point locations using empirically-based bathymetry rules to estimate a travel path between points. Distance classes in ten kilometer increments were established from a winter aggregation capture site. The distance increments were overlaid onto travel paths and, for each animal, the percentage of total travel within each increment was calculated. Travel path data indicated that females without calves occupied areas greater than 100 km from the winter site over 40% of the time and half of these paths were in areas greater than 200 km. In comparison, areas greater than 60 km were utilized only 0.5% of the time by females with calves. Habitat use was assessed by comparing telemetry point locations to the nearest seagrass patch. Distributions of distance-to-the-nearest-seagrass patch for female manatees with calves and those without calves were compared to each other and then to a random distribution of points. Results suggested that female manatees with calves selected habitat closer to their preferred winter aggregation site while female manatees without calves occupied a wider geographic range. The use of GIS to model and compare movement patterns derived from telemetry data have increased our knowledge of manatee travel behavior and is expected to help in manatee protection efforts.