The perception that crocodilians exhibit indeterminate growth is common in the general reptilian literature. However, this assumption is frequently based on observations of immature and young adult animals and therefore lacks a complete understanding of adult growth patterns. Long-term mark-recapture studies appear to be the most certain method of determining growth patterns of adult crocodilians. From 1979–2015, we conducted a mark-recapture study of an American Alligator (Alligator mississippiensis) population on the Tom Yawkey Wildlife Center (YWC) in coastal South Carolina to examine long-term growth patterns and the influence of age on multiple reproductive parameters. We found no discernible linear growth in 19 of 31 adult female and 7 of 19 adult male alligators over periods of 5–33 years. The mean maximum reproductive lifespan for female alligators on the study site was 46 years, and females continued to reproduce for an extended period of time after reaching maximum size. The Schnute growth model...
We used morphometric data from 1276 Crocodylus moreletii captured in northern Belize (1992–2001) to develop predictive models for determining body size (total length [TL], snout-vent length [SVL]) from measurements of single attributes (dorsal cranial length [DCL], cranial width [CW], snout length [SL] and width [SW], body mass [BM], rear-foot length [RFL]), quantify sexual size dimorphism, examine ontogenetic changes in cranial morphology, re-evaluate maximum body size attained by this species, and estimate standing crop biomass of crocodiles at our principal study site. Strong positive allometric relationships were found between measures of body length and other morphometric attributes, and provide a reliable means to estimate body length from tracks, skulls, and body parts. The maximum DCL:CW ratio is attained at a relatively small body size and preceded a dietary shift from insects and arachnids to vertebrates and ampullarid snails. The SL:SW ratio of C. moreletii is highly variable and beca...
Morelet's crocodile Crocodylus moreletii has not been well‐studied and many aspects of its life history are unknown. In particular there is a notable paucity of information on nesting and reproductive ecology. We studied the nesting ecology of Morelet's crocodile in northern Belize from 1992 through 1995. Nesting occurs at the onset of the wet season in mid‐June and continues through mid‐July (mean oviposition date =1 July±10 days). Eggs hatch from mid‐August through mid‐ to late September. Nesting effort at our primary study site remained relatively constant during 1992, 1993 and 1995, but nearly doubled in 1994; this appeared to reflect a regional trend. Natural and man‐made islands are heavily used as nesting sites. Nesting success in 1993 and 1994 was consistently higher on natural islands when compared with man‐made islands or shoreline sites. Nest losses were primarily due to flooding and raccoon Procyon lotor predation. Losses from predation were greatest in 1994 when unseasonably low water levels facilitated predator access to nests. Females probably reach sexual maturity in 7–8 years after attaining a total length of 150 cm. Mean clutch size (25.0±7.6; range=9–42; n=73) did not differ among years. Mean clutch size, egg width (EW), egg length, egg mass (EM) and clutch mass were positively correlated with female snout–vent length (SVL). Mean EW was the best predictor of female SVL. A partial correlation analysis of egg and clutch attributes found that independent of female SVL, EM increases with increasing clutch size.
Saurochory (seed dispersal by reptiles) among crocodilians has largely been ignored, probably because these reptiles are generally assumed to be obligate carnivores incapable of digesting vegetable proteins and polysaccharides. Herein we review the literature on crocodilian diet, foraging ecology, digestive physiology and movement patterns, and provide additional empirical data from recent dietary studies ofAlligator mississippiensis. We found evidence of frugivory in 13 of 18 (72.2%) species for which dietary information was available, indicating this behavior is widespread among theCrocodylia. Thirty‐four families and 46 genera of plants were consumed by crocodilians. Fruit types consumed by crocodilians varied widely; over half (52.1%) were fleshy fruits. Some fruits are consumed as gastroliths or ingested incidental to prey capture; however, there is little doubt that on occasion, fruit is deliberately consumed, often in large quantities. Sensory cues involved in crocodilian frugivory are poorly understood, although airborne and waterborne cues as well as surface disturbances seem important. Crocodilians likely accrue nutritional benefits from frugivory and there are noa priorireasons to assume otherwise. Ingested seeds are regurgitated, retained in the stomach for indefinite and often lengthy periods, or passed through the digestive tract and excreted in feces. Chemical and mechanical scarification of seeds probably occurs in the stomach, but what effects these processes have on seed viability remain unknown. Because crocodilians have large territories and undertake lengthy movements, seeds are likely transported well beyond the parent plant before being voided. Little is known about the ultimate fate of seeds ingested by crocodilians; however, deposition sites could prove suitable for seed germination. Although there is no evidence for a crocodilian‐specific dispersal syndrome similar to that described for other reptiles, our review strongly suggests that crocodilians function as effective agents of seed dispersal. Crocodilian saurochory offers a fertile ground for future research.
1 February 2020 in Ecotoxicology and Environmental Safety
Beginning in early 2006, an ocular disease of unknown etiology was routinely observed in American crocodiles (Crocodylus acutus) inhabiting the highly polluted Tarcoles River in west-central Costa Rica. We examined the nature and incidence of ocular disease in Tarcoles crocodiles and assessed the possible association between the disease and accumulation of chemical pollutants in diseased individuals. During 12-15 September and 12-13 December 2007, crocodiles were captured and examined for ocular disease and sampled to determine environmental contaminant accumulation. Three of 11 (27.3%) crocodiles captured (all males) exhibited unilateral ocular disease, primarily characterized by corneal opacity and scarring, anterior synechia, and phthisis bulbi. Multiple pollutants were detected in crocodile caudal scutes (organochlorine pesticides [OCPs] and metals), crocodile blood (OCPs), and sediments (OCPs and metals) from the Tarcoles, but no associations were found between contaminant accumulation and the incidence of eye disease. On the basis of the limited number of diseased animals examined and the potential exposure of crocodiles to pathogens and other pollutants not targeted in this study, we cannot rule out infection or chemical toxicosis as causes of the eye lesions. However, circumstantial evidence suggests that the observed ocular disease is likely the result of injury-induced trauma (and possibly secondary infection) inflicted during aggressive encounters (e.g., territorial combat) among large adult crocodiles living at relatively high densities.