This meat-eating animal feeds on fish, small mammals, reptiles, crustaceans and birds. Although there are physical and behavioural differences between a male and female crocodile, some are noticeable, but others require close inspection of a crocodile's body to recognise.

Measure the length of a crocodile. The most obvious sign that a crocodile is male or female is body size: males grow larger than females. The extent to which the sexes vary in size depends on the subspecies --- for example, the male saltwater crocodile can be double the length of a female, but a male Nile crocodile is usually only 30 per cent larger than a female.

Find the sexual organs. Locate the cloaca, a small vent on the underbelly of a crocodile. Gently use forceps on either side of the cloaca to open the cloaca. If the crocodile is female, a clitoris will pop out. If the crocodile is male, the penis will be found inside the cloaca.

Study the crocodile's behaviour during mating season. The male crocodile bellows loudly, slaps its snout in the water, blows water out of its nose and makes a variety of noises to get a female's attention.

Measure snout size. In some species of crocodile, females have a thinner snout and slenderer body than males.

Look to see if a crocodile has laid eggs after mating; only female crocodiles lay eggs. A female will lay between 20 and 40 eggs once a year in a nest near a river bank. If a crocodile is seen fiercely protecting a nest, the crocodile is most likely female; she will guard the nest until the eggs hatch and then carry her babies to the water to feed.