Friday, 6 November 2015

Everglades' alligator numbers drop after dry years

Date: October 30, 2015

Source: United States Geological Survey

Alligators and the Everglades go hand-in-hand, and as water conditions change in the greater Everglades ecosystem, gators are one of the key species that could be affected.

A recent study conducted by researchers from the U.S. Geological Survey, U.S. Fish and Wildlife Service and the University of Florida found the number of American alligators observed in the Arthur R. Marshall Loxahatchee National Wildlife Refuge dropped following dry years, and then appeared to recover in later non-dry years. The decrease in alligators appeared proportional to the intensity of the dry event. The refuge is located west of Boynton Beach, within the greater Everglades ecosystem.

"Alligator behavior and habitat use is linked to hydrology, and when that hydrology changes, alligator behavior and habitat can change," said USGS research ecologist Hardin Waddle, lead author of the study. "They don't need it wet all the time, but if dry events increase in frequency and intensity, this could be problematic for alligator numbers in the greater Everglades ecosystem."

Ten years of spotlight night counts in marsh and canals were analyzed to better understand the effect of annual minimum water depth on annual population growth rate. Years were considered dry if they experienced a drop in water level to 6 inches above the marsh surface. At this water level, alligators have difficulty moving around.

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