ONTOGENIC DIETARY PARTITIONING BY CROCODYLUS-JOHNSTONI DURING THE DRYSEASON

We examined size-related dietary patterns in a Queensland population o f the Australian freshwater crocodile (Crocodylus johnstoni). In three consecutive dry seasons, we stomach flushed crocodiles (n = 324) to r ecord the numerical frequency and percent occurrence of prey items, Pr ey included spiders, aquatic insects, terrestrial insects, shrimp, fis h, anurans, turtles, snakes, mammals, and birds. The diet of C. johnst oni showed ontogenetic shifts as the cranium broadened and once body s ize exceeded 60 cm SVL. With increasing crocodile size, the ingestion of spiders, insects, and anurans declined strongly whereas the consump tion of fish, turtles, and snakes increased strongly, Shrimp were eate n at low and variable levels by all size classes of crocodile, The low overall prevalence of mammals and birds suggested that they were cons umed opportunistically by the larger crocodiles, With increasing croco dile size, there were overall increases in prey richness and significa nt declines in realized dietary niche, dietary breadth, and mean numbe r of prey items per crocodile. There were no significant changes in di etary diversity, evenness, or number of equally common prey species.