Meeting Abstract

S3.10  Sunday, Jan. 4 14:30  Behavioral Ecology of the Gharial, Gavialis gangeticus LANG, Jeffrey W.; Madras Crocodile Bank, Univ. Minnesota

This study followed the 2007-08 mass mortality of gharial in the lower Chambal River, n. India. From 2008-2015, 40 radio-tagged gharials have been tracked during the monsoon and dry season annually, for 2+ yrs/animal. Individuals show different seasonal movements and residency patterns, dependent on size/age. Adult females move 80-120 km post monsoon to join dry season basking-breeding groups (60+ adults), and to locate communal nest sites. In contrast, sub-adult gharials exhibit restricted movements, 10-30 km seasonally, and occupy seasonal residencies only 5-15 km in extent. Some sedentary sub-adults showed virtually no movements, upstream or downstream. Gharial feed in June-September during the monsoon, and bask daily in November-February. Large aggregations form in December-January. Mixed basking groups of all age/size classes shift to groups of large sub-adults and adults by mid-February when courting and mating commence. Nesting occurs in late March/early April when reproductive females nest on sandbanks adjacent to deep water. At nest sites, yearlings (9 months old) often remain close to a resident large male which communicates with specific displays. Nesting colonies are common, but locations shift each year, depending on monsoonal changes in river topography. Adults guard nests during incubation. Females open nests, but do not transport the young to water. Females remain with hatchlings for 1-2 months, and guard them against potential predators. Large males, with well-developed and prominent gharas, often defend young (200-1000+) from 5-25+nests. Large crèches form, and young regularly feed on small fish. Biparental care, especially ‘paternal’ guarding of young, is likely the usual condition. These studies are relevant to conservation strategies, as well as an understanding of the biology of a distinctive species within a unique crocodilian lineage.