Seasonal Movements, Migratory Behavior, and Site Fidelity of West Indian Manatees along the Atlantic Coast of the United States as Determined by Radio-telemetry

The study area encompassed the eastern coasts of Florida, Georgia, and South Carolina,including inland waterways such as the St. Johns River (Fig. 1). Manatees inhabited therelatively narrow band of water that lies between the barrier beaches and the mainland,occasionally venturing into the ocean close to shore. Between Miami and Fernandina Beach,Florida, 19 inlets provided manatees with corridors between the intracoastal waters and theAtlantic Ocean; the distance between adjacent inlets averaged 32 km(SD = 24 km) and variedfrom 3 to 88 km. Habitats used by manatees along this 900-km stretch ofcoastline variedwidely and included estuaries, lagoons, rivers and creeks, shallow bays and sounds, and oceaninlets. Salinities in most areas were brackish, but ranged from completely fresh to completelymarine. The predominant communities of aquatic vegetation also varied geographically andwith salinity: seagrass meadows and mangrove swamps in brackish and marine waters along thesouthern half of peninsular Florida; salt marshes in northeastern Florida and Georgia; benthicmacroalgae in estuarine and marine habitats; and a variety of submerged, floating, and emergentvegetation in freshwater rivers, canals, and streams throughout the region.Radio-telemetry has been used successfully to track manatees in other regions ofFlorida(Bengtson 1981, Powell and Rathbun 1984, Lefebvre and Frohlich 1986, Rathbun et al. 1990)and Georgia (Zoodsma 1991), but these early studies relied primarily on conventional VHF (veryhigh frequency) transmitters and were limited in their spatial and temporal scope (see O'Sheaand Kochman 1990 for overview). Typically, manatees were tagged at a thermal refuge in thewinter and then tracked until the tag detached, usually sometime between the spring and fall ofthe same year. Our study differs from previous research on manatee movements in severalimportant respects. First, we relied heavily on data from satellite-monitored transmitters usingthe Argos system, which yielded a substantially greater number of locations and more systematiccollection of data compared to previous VHF tracking studies (Deutsch et al. 1998). Second, ourtagging and tracking efforts encompassed the entire range of manatees along the Atlantic coast,from the Florida Keys to South Carolina, so inferences were not limited to a small geographicarea. Third, we often used freshwater to lure manatees to capture sites, which allowed taggingin all months of the year; this provided more information about summer movement patterns thanhad previous studies which emphasized capture and tracking at winter aggregations. Finally, thestudy spanned a decade, and success in retagging animals and in replacing transmitters allowedlong-term tracking ofmany individuals. This provided the opportunity to investigate variation inseasonal movements, migratory behavior, and site fidelity across years for individual manatees.(254 page document.)

Bibliographic Details

Main Authors:	Deutsch, Charles J., Reid, James P., Bonde, Robert K., Easton, Dean E., Kochman, Howard I.
Format:	monograph biblioteca
Language:	English
Published:	Florida Cooperative Fish and Wildlife Research Unit , University of Florida 2000
Subjects:	Biology, Limnology, Information Management, West Indian Manatees, radio-telemetry, movements, Atlantic Coast, tracking, Florida, Georgia, South Carolina,
Online Access:	http://hdl.handle.net/1834/18948
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