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Keywords:

  • Florida manatee;
  • Trichechus manatus latirostris;
  • Sarasota County;
  • habitat selection;
  • calves;
  • refuge;
  • conservation

Abstract

Habitat selection by Florida manatees (Trichechus manatus latirostris) is influenced by, among other things, availability of food, thermal, and freshwater resources. However, habitat selection by females with dependent calves may differ from that of other demographic groups with regard to the relative importance of these factors. Additional factors that may influence habitat selection for females with dependent calves include ambient noise, strong currents, or increased foraging requirements. We examined distributional data for manatees from aerial surveys of the coastal waters near Sarasota, Florida, between 1994 and 2004 to determine whether habitat selection by groups of manatees that included calves differed from that of other groups. We characterized groups according to their location within seven habitat types. Enclosed bays not traversed by the Intracoastal Waterway had the highest proportions of groups with calves. Groups with calves used a No Entry refuge (from which almost all human use is barred) to a greater extent than did other groups. Overall, groups with calves exhibited significantly different habitat selection from groups without calves (P < 0.001, χ2= 43.0, df = 6), but this was not consistent across seasons. During the winter and spring, thermal requirements influenced manatees to such an extent that all demographic groups selected habitat similarly.