Crocodylus johnstoni in the McKinlay River Area N. T, V.* Abnormalities and Injuries

Abstract

Abnormalities and injuries in a sample of 797 C. johnstoni are described. 56.3% of animals were scarred or freshly injured, and 81.1% of injured animals had the tail injured. Rake and bite marks were the most common injury, and these apparently result from intraspecific interactions, perhaps including a specific 'tail-biting' behaviour. Interspecific comparisons indicate the frequencies of injuries are greatest in species which congregate in high densities, namely C. johnstoni and Caiman c. crocodilus. Nematode worm trails were rarely encountered on C. johnstoni under 31 cm snout-vent length (SVL) but were on 100% of animals over 80 cm SVL. Leeches were on 59% of animals caught in one area during the wet season, but only 2.6% of those caught further upstream in the dry season. The SVLs at which mandibular teeth protrude through the premaxilla are quantified and the significance of tooth protrusion discussed.