Crocodilians show universal parental care, but few studies concentrate on this behavior in wild crocodiles. We studied nest and hatchling care in genetically pure wild American crocodiles (Crocodylus acutus) on two Caribbean islands of Mexico. From 2006 to 2009 we made direct observations of crocodile behavior upon discovery of nests and groups of hatchlings in Banco Chinchorro. In 2009, we installed camera traps at 4 nests from the time of their discovery to the hatching of each nest, in Banco Chinchorro and Cozumel Island. Twenty-one other species were observed to visit crocodile nests. No nest predation was observed but nine species represented some danger to nests and/or hatchlings. Females seemed to remain in the nest vicinity during incubation. There was variability in nest visit frequencies and no nest defense toward human intrusion was observed. Visit frequency by other species at nests decreased with increased crocodile visitation. Crocodiles mainly visited nests on darker nights, corresponding to the visits of species representing greater danger for nests. Repair of the nest by females after disturbance was observed for the first time in wild American crocodiles. Crocodile visits were more frequent at the beginning and the end of incubation, which could represent different antipredation strategies. Although adult crocodiles helped during hatching for the emergence of neonates, hatchling care seemed reduced compared to other crocodile species. We provide the first data on nesting behavior of genetically pure American crocodiles in the Yucatan peninsula, which provides a base for future comparisons with Morelet's crocodiles and their hybrids.

Crocodylus acutus, a coastal species nesting in sand beaches, could be affected by increasing tropical cyclone frequency. We studied key characteristics of C. acutus reproductive ecology on Banco Chinchorro atoll from 2006 to 2009, including the impact of two tropical cyclones. Hurricanes increased canopy openness causing earlier nesting the following year. Crocodiles nested at the beginning of the wet season with hatching in mid-wet season; this could represent a compromise between risking nest flooding and increasing freshwater availability for hatchlings. Tropical cyclones dramatically reduced nesting success by cooling and flooding clutches. Nursery sites were usually hypersaline, but heavy rainfall from tropical cyclones can likely benefit hatchling survival by decreasing salinity. While tropical cyclones have negative short-term impacts on crocodile nesting, they likely have an overall beneficial effect by creating and maintaining open sandy nesting areas used by C. acutus and they may explain its widespread distribution in Caribbean coastal areas.

Bacterial cultures and chemical analyses were performed from cloacal and oral swabs taken from 43 American crocodiles Crocodylus acutus and 28 Morelet's crocodiles C. moreletii captured in Quintana Roo State, Mexico. We recovered 47 bacterial species (28 genera and 14 families) from all samples with 51.1% of these belonging to the family Enterobacteriaceae. Fourteen species (29.8%) were detected in both crocodile species and 18 (38.3%) and 15 (31.9%) species were only detected in American and Morelet's crocodiles, respectively. We recovered 35 bacterial species from all oral samples, of which 9 (25.8%) were detected in both crocodile species. From all cloacal samples, we recovered 21 bacterial species, of which 8 (38.1%) were detected in both crocodile species. The most commonly isolated bacteria in cloacal samples were Aeromonas hydrophila and Escherichia coli, whereas in oral samples the most common bacteria were A. hydrophila and Arcanobacterium pyogenes. The bacteria isolated represent a potential threat to crocodile health during conditions of stress and a threat to human health through crocodile bites, crocodile meat consumption or carrying out activities in crocodile habitat. We especially warn about the presence of Salmonella arizonae and S. typhi, which cause enteritis and septicemia in crocodiles and salmonellosis and typhoid fever in humans. The risk of bacterial contamination from crocodiles to humans could increase in the future because of the accelerated destruction of crocodile habitat, which could lead to an augmentation of human-crocodile interactions. Information on bacterial diversity reported here could help in the choice of antibacterial products in case of infections that are of crocodile origin.

As top predators, crocodilians can bioaccumulate high concentrations of persistent organochlorine pesticides (OCPs) that may have adverse effects on their physiology and health. Recent and illegal uses of OCPs in Mexico could affect populations of the American crocodile (Crocodylus acutus), already threatened by other factors. We analyzed 16 OCP compounds using gas chromatography with electron capture detection in seven infertile eggs and in the substratum of nine nests of American crocodiles in Banco Chinchorro, an atoll off the Mexican coast of the Yucatan peninsula. Nest type, clutch size and distance from nests to nearest lagoon were also recorded, while total length of the females attending each nest was measured directly or estimated. Although Banco Chinchorro is isolated from the mainland and from known sources of contamination, OCP residues were detected in egg and nest substratum samples collected from the atoll. OCP concentrations in eggs (range: 0.002–4.000 ppb) and nest substrata (ra...