Characterization of Resting Holes and Their Use by the Antillean Manatee (Trichechus manatus manatus) in the Drowned Cayes, Belize

Abstract: In the Drowned Cayes area of Belize, manatees (Trichechus manatus manatus) are commonly observed resting in depressions in the substrate, locally referred to as manatee resting holes. To understand why manatees prefer locations with resting holes, the physical and environmental attributes of the depressions were characterized and diurnal and nocturnal use by manatees at four resting hole sites were documented over two summers. Twelve resting hole sites were compared with 20 non-resting hole sites in the Drowned Cayes, using water depth, substrate type, vegetation, water velocity, salinity, and water temperature. Four resting holes were chosen for repeated diurnal and nocturnal observations, during which sea and weather conditions were recorded in addition to the presence/absence of manatees. Resting holes were significantly deeper and had slower surface water velocity than areas without resting holes. A total of 168 point scans were conducted over 55 d, resulting in 39 manatee sightings over two summers. There was a significant difference in the number of sightings between research years and between day and night scans. Given the large number of resting holes in the Drowned Cayes, many of which are in sheltered areas with slow currents, it is possible that manatees select these spots based on the tranquility of the water and environment. The combination of slow currents, protection from waves, low numbers of boats, and nearby seagrass beds would make these ideal resting areas. These findings have implications for the conservation of important manatee habitat.

Key Words: Antillean manatee, Trichechus manatus manatus, Belize, resting holes, nocturnal, diurnal, conservation, habitat, sightings

Document Type: Research article

DOI: 10.1578/AM.35.1.2009.62

Page Numbers: 62-71

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