Gavialis males mature at about 11.5 ft (3.5 m) at the age of 15, when the narial excresence becomes large and rounded. Females mature at 10 ft (3 m), as young as eight years old. The breeding season is markedly seasonal throughout the
range of the species; courtship and mating occur in December to January and nesting from March to May. The duration of the nesting season is shorter at higher latitudes (22 days on the Narayani River in Nepal) and longer at southerly latitudes (57 days at the Madras Crocodile Bank). Evidence from captive-breeding studies indicates that larger females nest first, inferring that these females are mated with first. Females select nest sites at least 5 ft (1.5 m) above water level, and may dig trial nests before nesting. Clutch size closely correlates with the size of the female, ranging from 12 to nearly 100 eggs in very large females. The first clutches laid by females typically contain a high proportion of infertile eggs. Eggs measure 2.2 by 3.4 in (55 by 86 mm), and weigh 5.5 oz (156 g). Embryonic development is rapid, particularly in the later stages of development. Incubation temperature determines the incubation period and sex of hatchlings, as well as hatchling size. Incubation period is shorter at higher temperatures (an average of 53 days at 91°F/33°C) and longer at lower temperatures (93 days at 82°F/28°C). Females have been observed to guard nests in the wild, dig out hatchlings from nests, and display prolonged protection of their crèche of hatchlings. Males may also protect the young. Eggs are
A pair of gharials (Gavialis gangeticus) enjoy the waters of India. (Photo by Michael Fogden. Bruce Coleman, Inc. Reproduced by permission.)
preyed upon by jackals, pigs, hyenas, mongooses, and monitor lizards. Hatchling mortality is high, largely due to floods in the monsoon period (when the eggs hatch), and predation by large wading birds and soft-shelled turtles.
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