Year

2022

Season

Spring

Paper Type

Master's Thesis

College

College of Arts and Sciences

Degree Name

Master of Science in Biology (MS)

Department

Biology

NACO controlled Corporate Body

University of North Florida. Department of Biology

First Advisor

Dr. Adam Rosenblatt

Second Advisor

Dr. Joseph Butler

Third Advisor

Dr. Marisa Tellez

Department Chair

Dr. Cliff Ross

College Dean

James Garner

Abstract

Crocodilian populations declined globally during the 20th century because of overhunting and habitat loss. Some crocodilian populations have recovered recently through legal protections and habitat restoration, but the status of many crocodilian populations are still unknown because of a lack of recent data. The American crocodile (Crocodylus acutus) population in the Dominican Republic (DR) is one of these data-deficient populations, with country-wide surveys not carried out since the 1980s. From May through July 2021 we surveyed areas within DR where C. acutus is still likely residing. Our surveys yielded no crocodile sightings in Monte Cristi, suggesting that crocodiles have been extirpated or nearly extirpated from this area. Our surveys of Lago Enriquillo produced 120 crocodile sightings over 72.6 km of shoreline, for an encounter rate of 1.2 crocodiles/km. Encounter rates were very high in the main nursery area of the lake (La Azufrada; 60.0 crocodiles/km). 42 nests were located in Lago Enriquillo. Our data suggest that the DR population of C. acutus is critically endangered and is continuing to decline due to the pressures of hunting, fishing, and habitat destruction. To better understand this population’s life history and how it interacts within Lago Enriquillo’s community, we studied diet, size and sex-related dietary patterns, and niche width to make more informed conservation management decisions. Based on percent Index of Relative Importance (%IRI) values, crustaceans and fishes dominate the diet of juveniles while subadults eat a greater proportion of fishes and broaden their diets to include birds and mammals. A statistical analysis of individual specialization indicates that juveniles have significantly more specialized diets in comparison to a null model, but they are only moderately specialized. Cannibalism was confirmed from the stomach contents of a juvenile in La Azufrada, which has major implications for conservation efforts because of low recruitment in this population.

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