Diet of Spectacled Caimans (Caiman crocodilus) Removed from Broward and Miami-Dade Counties, Florida, USA

Spectacled Caimans (Caiman crocodilus) are an approximately 2 m long crocodilian native to Central and South America. Caimans were introduced in southern Florida, USA in the mid-1950s and have occurred primarily in Palm Beach, Broward, and Miami-Dade Counties. Our study characterizes the diet of Spectacled Caimans removed from Broward and Miami-Dade counties based on samples collected from gastrointestinal (GI) tracts. GI samples were rinsed, sorted, dried, examined, and identified to the lowest taxonomic level possible. We calculated diversity metrics for prey items and percent dietary overlap to assess differences in caiman prey by size class, sex, season, and area. We examined 108 GI tracts (49 males, 20 females, 39 of undetermined sex) from 32 hatchlings, 53 juveniles, and 23 adults collected over six years (2017–2022) and identified 685 prey items from 107 individuals. Only one caiman had no identifiable prey items in the GI tract. Insects were the most common prey item recovered from GI tracts of all size classes, sexes, and seasons. We found evidence of ontogenetic diet changes with hatchlings almost exclusively preying on insects, juveniles frequently preying upon malacostracans and reptiles, and adults preying upon gastropods and reptiles. Adult caimans exhibited the highest dietary diversity and evenness, females exhibited higher diversity and evenness than males, and dry season captures exhibited higher diversity and evenness than wet season captures. Our observations confirm that Florida's Spectacled Caimans are dietary generalists whose broad diets and apparent geographic expansion could negatively impact native species where they occur.