<P> During the mating season, males attract females by bellowing, slapping their snouts in the water, blowing water out of their noses, and making a variety of other noises . Among the larger males of a population, territorial clashes can lead to physical fighting between males especially if they are near the same size . Such clashes can be brutal affairs and can end in mortality but typically end with victor and loser still alive, the latter withdrawing into depth waters . Once a female has been attracted, the pair warble and rub the undersides of their jaws together . Compared to the tender behaviour of the female accepting the male, copulation is rather rough (even described as "rape" - like by Graham & Beard (1968)) in which the male often roars and pins the female underwater . Cott noted little detectable discrepancy in the mating habits of Nile crocodiles and American alligators . In some regions, males have reportedly mated with several females, perhaps any female that enters his claimed territory, though in most regions annual monogamy appears to be most common in this species . </P> <P> Females lay their eggs about one to two months after mating . The nesting season can fall in nearly every month of the year . In the northern extremes of the distribution (i.e. Somalia or Egypt), the nesting season is December through February while in the southern limits (i.e. South Africa or Tanzania) is in August through December . In crocodiles between these distributions egg - laying is in intermediate months, often focused between April and July . The dates correspond to about a month or two into the dry season within that given region . The benefits of this are presumably that nest flooding risk is considerably reduced at this time and the stage at which hatchlings begin their lives out of the egg falls roughly at the beginning of the rainy season, when water levels are still relatively low but insect prey is in recovery . Preferred nesting locations are sandy shores, dry stream beds, or riverbanks . The female digs a hole a few metres from the bank and up to 0.5 m (20 in) deep, and lays on average between 25 and 80 eggs . The number of eggs varies and depends partially on the size of the female . The most significant prerequisites to a nesting site are soil with the depth to permit the female to dig out the nest mound, shading to which mother can retire during the heat of the day and access to water . She finds a spot soft enough to allow her to dig a sideways slanted burrow . The mother Nile crocodile deposits the eggs in the terminal chamber and packs the sand or earth back over the nest pit . While, like all crocodilians, the Nile crocodile digs out a hole for a nest site, unlike most other modern crocodilians, female Nile crocodiles bury their eggs in sand or soil rather than incubate them in rotting vegetation . The female may micturate sporadically on the soil to keep it moist, which prevents soil from hardening excessively . After burying the eggs, the female then guards them for the three - month incubation period . Nests have been recorded seldom in concealed positions such as under a bush or in grasses, but normally in open spots on the bank . It is thought the Nile crocodile cannot nest under heavy forest cover as can two of the three other African crocodiles because they do not utilize rotting leaves (a very effective method of producing heat for the eggs) and thus require sunlight on sand or soil the surface of the egg chamber to provide the appropriate warmth for embryo development . In South Africa, the invasive plant Chromolaena odorata has recently exploded along banks traditionally used by crocodiles as nesting sites and caused nest failures by blocking sunlight over the nest chamber . </P> <P> When Nile crocodiles have been entirely free from disturbance in the past, they may nest gregariously with the nest lying so close together that after hatching time the rims of craters are almost contiguous . These communal nesting sites are not known to exist today, perhaps being most recently recorded at Ntoroko peninsula, Uganda where two such sites remaining until 1952 . In one area, 17 craters were found in an area of 25 yd × 22 yd (75 ft × 66 ft), in another 24 in an area of 26 yd × 24 yd (78 ft × 72 ft). Communal nesting areas also reported from Lake Victoria (up until the 1930s) and also in the 20th century at Rahad River, Lake Turkana and Malawi . The behaviour of the female Nile crocodile is considered unpredictable and may be driven by the regional extent of prior human disturbance and human persecution rather than natural variability . In some areas, the mother crocodiles will only leave the nest if she needs to cool off (thermoregulation) by taking a quick dip or seeking out a patch of shade . Females will not leave nest site even if rocks throw at her back and several authors note her trance - like state while standing near nest, similar to crocodiles in aestivation but not like any other stage in their life - cycle . In such a trance, some mother Nile crocodiles may show no discernable reaction even if pelted with stones . At other times, the female will fiercely attack anything approaching their eggs, sometimes joined by another crocodile which may be the sire of the young . In other areas, the nesting female may disappear upon potential disturbance which may allow the presence of both the female and her buried nest to escape unwanted detection by predators . Despite the attentive care of both parents, the nests are often raided by humans and monitor lizards or other animals while she is temporarily absent . </P> <P> At a reported incubation period of about 90 days, the stage is notably shorter than that of the American alligator (110--120 days) but slightly longer than that of the mugger crocodile . Nile crocodiles have temperature - dependent sex determination (TSD), which means the sex of their hatchlings is determined not by genetics as is the case in mammals and birds, but by the average temperature during the middle third of their incubation period . If the temperature inside the nest is below 31.7 ° C (89.1 ° F), or above 34.5 ° C (94.1 ° F), the offspring will be female . Males can only be born if the temperature is within that narrow range . The hatchlings start to make a high - pitched chirping noise before hatching, which is the signal for the mother to rip open the nest . It is thought to be either difficult to impossible for hatchlings to escape the nest burrow without assistance, as the surface may become very heavy and packed above them . The mother crocodile may pick up the eggs in her mouth, and roll them between their tongue and the upper palate to help crack the shell and release her offspring . Once the eggs hatch, the female may lead the hatchlings to water, or even carry them there in her mouth, as female American alligators have been observed doing . </P>

The nile crocodile can hold its breath underwater for up to 2 hours while waiting for prey