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Nesting biology and ecology have been investigated for Nile crocodiles ( Crocodylus niloticus ), but information on behaviour and movement patterns of nesting females during nest guarding is scant. Consequently, we investigated the home ranges, nest-site selection strategies, movement patterns, activity levels and nest fidelity of four nesting females using telemetry. Gravid females selected winter basking/breeding areas close (351 ± 2 m) to nest-sites. Mean home range and core-use areas of nesting females were 8539 ± 4752 m 2 , and 4949 ± 3302 m 2 respectively. Mean home range (0.85 ha) was significantly smaller than those of non-nesting females (108.4 ha) during nesting season. Activity levels and mean daily movements while nesting were 8.1 ± 2.5% and 213 ± 64 m, respectively, and increased to 47.9 ± 11.7% and 2176 ± 708 m post-nesting. Overall levels of nest fidelity were 82.8 ± 11.7%, (day 78.1 ± 15.9%; night 87.3 ± 7.8%). Highest nest fidelity recorded during incubation was 99.7% over 96 days. Telemetry data from nesting females were helpful for elucidating spatial and behavioural patterns during the nest guarding period, and provided novel insights into this biologically important event. [ABSTRACT FROM AUTHOR]

Information regarding nest predation, nest abandonment, and maternal care in the Nile crocodile ( Crocodylus niloticus ) is largely restricted to anecdotal observations, and has not been studied quantitatively. Consequently, we investigated their nesting biology using camera-traps over four years at Lake St Lucia, South Africa. We obtained 4305 photographs (daylight captures = 90.1%, nocturnal = 9.9%) of 19 nest-guarding females. Of 19 monitored nests, 37% were raided by predators (mean = 12.1 ± 6.2 days subsequent to camera placement). All females returned to their nests following first predation, and on average returned three times between predator raids before nest abandonment. Water monitors ( Varanus niloticus ) and marsh mongoose ( Atilax paludinosus ) were the main egg predators. Nesting raids lasted 5.9 ± 1.6 days. Diurnally females were seldom on the nest, except during cool/cloudy weather or rain, preferring to guard from nearby shade. Females defended nests aggressively against non-human intruders. Five Nile crocodile females were observed liberating their hatchlings from nests. A detailed sequence of a mother excavating and transporting hatchlings revealed 13 excursions between nest and water over 32.5 h. This, after months of continual nest attendance and defence, is illustrative of the high level of maternal care in Nile crocodiles. Camera-trapping is an effective, non-invasive method for further crocodile nesting behaviour research. [ABSTRACT FROM AUTHOR]