Diet and Condition of American Alligators in 4 Florida Lakes

We examined stomach contents from 219 American alligators (Alligator mississippiensis) collected from 4 Florida lakes. Fish, mostly shad (Dorosoma spp.), bowfin (Amia calva), and gar (Lepisosteus spp.) occurred in 55.3% of the stomachs and was the most important food group (57.5%) by volume. Apple snails (Pomacea paludosa) and crayfish (Procambarus spp.) were important invertebrate prey (66.7% occurrence and 6.6% by volume). Of the 195 stomachs having a dominant food type (>50% of the total food volume), most (72%) contained one food type exceeding 90% of the total food volume. The predominant food type differed by lake (P< 0.001), sex (P= 0.056), and size (P< 0.001) of the alligator. In general, the dominant food type changed from invertebrate to vertebrate with an increase in alligator size. Alligator length-weight relationships (condition) were examined for variation associated with diet. For large alligators (2.89 m total length [TL]), increasing probability of dominance by the fish food type was associated with better condition. Fish were more likely to be the dominant food for alligators in lakes with the highest chlorophyll a concentrations. Food resources limitations may affect alligator diet and condition at some locations. Information on dietary constraints and condition may be useful in managing American alligators for commercial and conservation purposes.

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