The successful survival of crocodilian hatchlings is largely dependent upon nest care by females. Nonetheless, it is crucial to understand how environmental degradation affects nest site selection and parental behaviour in female crocodilians. Therefore, our objective was to evaluate the relationship between anthropogenic disturbances and nesting behaviour in free-living broad-snouted caiman (Caiman latirostris). We compared nests in a disturbed and a non-disturbed area, and anticipated differences in nest density, hatching success, female size, egg number and biomass, and parental care behaviour. We monitored 44 nests over four years in Brazil, covering 58.25 km, in a disturbed area (n = 8) and a non-disturbed area (n = 36). According to our findings, nest density was significantly higher in the non-disturbed area (1.31 nests per linear km) compared to the disturbed area (0.25 nests per linear km). However, there was a significantly higher frequency of parental care behaviour (86%) in the disturbed area compared to the non-disturbed area (34%). The other factors studied showed no statistical difference between the two areas. The results indicate that females prefer to nest in healthier, preserved environments, away from anthropogenic disturbances. Yet, presumably at the cost of extra energy expenditure, increased parental care appears to buffer against a reduction in hatching success. Despite the behavioural buffer, the clear preference for non-disturbed nesting and nursery locations underscores the need to identify and protect the remaining non-disturbed areas inhabited by these animals. Our findings suggest that these measures should positively impact the welfare and protection of C. latirostris and other crocodilian species.

Tomistoma schlegelii is a threatened crocodilian whose current range is restricted to Sumatra, Borneo (Kalimantan and Sarawak) and Peninsular Malaysia. During surveys undertaken in eastern Sumatra in 1995–1996, 15 T. schlegelii nests were located in peat swamp forest along a single tributary, the Merang River. No other areas with equivalent nest densities have yet been described. Although much peat swamp forest has been lost to logging and fire, it remains the dominant habitat in most of the current range of T. schlegelii. In the Merang River the peat swamp and T. schlegelii are threatened by a series of ongoing activities and both may be lost unless some form of innovative management programme is introduced. Peat swamp forest supports a range of other rare and threatened species, and would appear to have high conservation value. This paper reviews current information on the role of peat swamp forest in the ecology of T. schlegelii and describes the conservation threats to T. schlegelii in the Merang River.

Recent theoretical papers on temperature-dependent sex determination in reptiles are based on the assumption that crocodilian populations, particularly adults, are markedly female biased. While there is evidence that some crocodile populations may conform to this expectation, there is no compelling evidence that American alligator populations are female biased anywhere in the species' range. Previous data had indicated that some populations of juvenile and/or adult alligators were significantly male biased. However, these studies were criticized for sampling errors. Adult males typically occupy a different habitat from that of females, and males frequent areas where they are more likely to be caught. In contrast, in juveniles, both sexes occupy the same habitat. We determined the sex ratios of c. 3000 juvenile alligators collected from 11 sites over 6 years in south Louisiana. Our results indicate a significant sex bias (58% male), but variation was evident among samples. Sex ratios varied by year and site, and the interaction of these factors was significant. At one site in one year, there was a female bias (71%), but in no year was there an overall female bias across sites. From this study and earlier reports, we conclude that there is no evidence at present of female-biased sex ratios in the juvenile and/or adult alligator populations, and consequently, that certain models of temperature-dependent sex determination in reptiles require re-evaluation. Furthermore, our data suggest a pattern of differential mortality of females vs males during the first years of life, a pattern consistent with a key prediction of several differential fitness models for the adaptive significance of temperature-dependent sex determination in reptiles.