Mating of saltwater crocodiles occurs in September/October, which is the wet season. During breeding season, female saltwater crocodiles protect and guard their nesting area heavily against other females; they will also prevent unwanted males from entering their territory during this time.
Males will also defend their areas against other males. While highly aggressive, males will try to avoid fighting by first using intimidation tactics, such as tail waving, jaw opening, vocalisation and head lifting. Dominant males will raise their entire bodies out of the water, while submissive males will raise their heads above the water and vocalise. The males will only fight if intimidation does not work.
Nesting
Nesting generally begins at the beginning of the wet season (late October) and ends in May or June, the end of the wet season.
Female saltwater crocodiles choose a secluded area in which to nest, generally close to a permanent water source. Female saltwater crocodiles build high nests made of mounds of grasses, plant material and mud. The mounds are built as high as possible to aid in protecting the eggs and nest from becoming flooded. If the eggs become too wet or too dry, thee crocodile embryos will die.
Webb and Manolis in Australian Crocodiles: A Natural History (1989:79), state that "the construction of nests may take up to one week, and once complete can be between 33 and 80 cm high, 130 to 250 cm long, and 120 to 225 cm wide".
Embryo Development
Females generally lay between 40 - 60 eggs, but this will vary on the age and size of females; the laying process takes approximately one hour. Within several hours of being laid, the embryos will attach themselves to the eggshell, which will appear as a white spot.
Hatchling saltwater crocodiles are born approximately 29 cm in length after an incubation period of approximately 80 days. The sex of the crocodiles is determined by temperature: a nest temperature of 31.6 degrees C will produce more males; females tend to be produced at slightly above and below this temperature. However, if tempertures are above 34 degrees C, the eggs (and therefore the young crocodiles), will die.
Webb and Manolis note that saltwater crocodiles eggs (and therefore embryos) suffer a high mortality rate due to flooding during the wet season, with over 90% of the nests made on the river banks becoming submerged. As embryos need to breathe through the eggshell and shell membrane, they will drown if submerged in water.
The behaviour of female saltwater crocodiles after nesting varies between individuals, although they tend to be most aggressive immediately after laying the eggs and during the hatching period.
Female saltwater crocodiles are quite protective of their nests, and will protect them until the eggs hatch; on hearing the hatchlings crying, the females will aid them by digging into the nest and helping them escape. Females will then carry the hatchlings in her mouth to the water. Once in the water, the young will stay close to the mother in a creche-like set-up for a few months. During this time, she will try to protect them against predators (which includes other crocodiles, primarily males).
Unfortunately, only 1% of hatchlings will reach maturity.
Source:
Webb, Grahame and Manolis, Charlie. 1989. Australian Crocodiles: A Natural History. Reed Books Australia. Frenchs Forest: NSW
Crocodile Learning Zone
Antonietta Salerno - I am passionate about all areas of animal welfare and the environment, and have a firm belief that everything that is living on this ...
