Reproductive Dynamics of an Isolated Population of American Crocodiles (Crocodylus acutus) Based on Long-term Monitoring Data

Abstract

The American Crocodile (Crocodylus acutus) is still considered Vulnerable, with some populations remaining depressed and showing little evidence of recovery. An understanding of the reproductive dynamics and parameters of C. acutus is essential for its conservation and management. Although the knowledge of C. acutus reproductive ecology has greatly increased during recent years, some critical parameters such as breeding effort (i.e., proportion of adult females that nest each year in a population) remain poorly known. Herein we analyzed 14 yr of reproductive data from a C. acutus population in a Mexican atoll to better understand its reproductive dynamics in space and time. We estimated the number of reproductive females in the population and in each nesting area, compared nest characteristics and clutch parameters among nesting areas, and determined female breeding effort and breeding frequency (i.e., proportion of years that an adult female nested). We estimated that 35 reproductive female C. acutus inhabit the main island of the atoll, distributed among 12 nesting areas. The annual female breeding effort ranged from 27.3–60.6% and the breeding frequency of 15 selected females ranged from 57.1–92.3%. Breeding effort depends on the breeding effort in preceding years. We also found significant differences in reproductive attributes (i.e., number of nests, nest–water distance, nest depth, clutch size, and nesting success) among nesting areas that we explain by the quality of those habitats for crocodile nesting and by territorial behavior of females.