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The American crocodile (Crocodylus acutus) is the most widely distributed New World crocodile. However, the species has experienced severe declines due to overexploitation. In South Florida, loss of nesting habitat, with coastal degradation from sea level rise and urban development has prompted American crocodiles to nest in novel habitats. Crocodile Lake National Wildlife Refuge (CLNWR) serves as an important nesting site for the South Florida population of American crocodiles and more recently nesting habitat has been supplemented to manage coastal erosion. The goal of this study was to investigate the internal nest biology of American crocodile nests laid in sediment nourished sand mounds on CLNWR. We monitored internal nest temperature and volumetric water content of five live and two control sand nests in 2021 (N = 73 eggs) and 2022 (N = 84 eggs). The metabolic heat generated by incubating eggs in internal nest temperatures ranged from 0.8°C to 2.0°C warmer and more stable than ambient temperatures and reflecting a seasonal pattern. Average clutch size was 31.4 ± 7.09 eggs and incubation period ranged from 78 to 114 days until hatching. These data provide the first insight into thermal regimes of nests laid in novel/supplemented nesting habitat as is the case for a significant proportion of nests in the South Florida population of American crocodiles. Here we provide an opportunity to evaluate the importance of creating artificial nesting habitat for American crocodiles where habitat degradation from climate change threatens species survival. [ABSTRACT FROM AUTHOR]

The range of the threatened American crocodile (Crocodylus acutus) in the United States is limited to the southernmost parts of Florida. As this species has recovered concurrently with an increasing human population, human–crocodile conflicts have also increased. Resolving conflicts can involve translocating crocodiles; however, they often return to the site from which they were removed. We examined the effects of translocation on crocodile movements, habitat use, body condition, and survival in Florida, USA, in 2018–2019 to refine recommendations for managers considering translocation to resolve human–crocodile conflict. We captured and attached global positioning system (GPS) units to 17 crocodiles, 10 of which served as a reference group (free‐ranging crocodiles released at their capture site) and 7 served as a treatment group (crocodiles that were translocated 14–158 km from their capture site). We collected location data from individual crocodiles for 34–661 days (x¯ $\mathop{x}\limits^{̅}$ ~ 250 days for each group). Body condition was similar for both groups. Corticosterone levels measured periodically during handling indicated that crocodiles experienced increasing stress levels during handling. Three crocodiles translocated ≤45 km from their original capture site returned to that location within 13 days. Three crocodiles translocated ≥110 km did not return. One female translocated 152 km was recaptured 0.42 km from its original capture site 965 days after its release. We identified 2 states of characteristic movement patterns: state 1 indicated individuals moving slowly and somewhat randomly, and state 2 indicated individuals exhibiting fast, active directional movement. Translocated individuals were more likely than reference individuals to switch to, and stay in, state 2. Because of concerns regarding return rates and heightened stress as a result of capture and translocation, we suggest crocodile translocations have limited conservation value and may only be worth considering once all other reasonable options are exhausted. [ABSTRACT FROM AUTHOR]

The American crocodile Crocodylus acutus occurs across the Americas, with its northernmost distribution being in South Florida, USA. This species has undergone severe declines across its range and is categorized globally as Vulnerable on the IUCN Red List and as Threatened on the U.S. Federal Endangered Species List. Long-term monitoring studies in the USA have documented a shift in American crocodile nesting activity and an expansion of its range throughout the southern and eastern coasts of South Florida. However, no successful American crocodile nests have been recorded until now on the west coast of South Florida. Here we document the American crocodile nest monitoring conducted during 1997–2021 at Rookery Bay National Estuarine Research Reserve and the first successful nest from the west coast of South Florida for C. acutus. Marco Airport and McIlvane Marsh are the two main American crocodile nesting areas identified at the Reserve, with 92 nests and 3,586 eggs recorded during 1997–2021. We found most nests at Marco Airport (95.7%) and only four nests (4.3%) at McIlvane Marsh. To date, none of the nests found at Marco Airport have produced successful hatchlings. In contrast, hatchlings have been produced at McIlvane Marsh since nests were first documented there in 2020. We discuss the implications of our findings in terms of the future conservation of the species. [ABSTRACT FROM AUTHOR]

Negative interactions between people and crocodilians have increased worldwide, but in Mexico there have been few systematic reports and no rigorous evaluation of this problem. We compiled information on negative interactions between people and the spectacled caiman Caiman crocodilus and American crocodile Crocodylus acutus from the Worldwide Crocodilian Attack Database for 1993–2018, and we investigated interactions in greater depth, through interviews with people in La Encrucijada Biosphere Reserve. We examined the relationship between the occurrence of negative interactions between people and C. acutus and the species' nesting season and abundance, and presence records. In Mexico, the frequency of negative interactions increases when anthropogenic activities occur close to nesting sites (< 30 km) and during the nesting season (February–September). In La Encrucijada, following negative interactions with crocodiles, the local inhabitants killed 30 crocodiles measuring > 2.5 m long in 2011–2012. The frequency of negative human–crocodilian interactions was not correlated with the abundance of crocodilians but was correlated with the number of presence records of crocodiles. Strategies to minimize these interactions include warnings at nesting sites, increased monitoring of anthropogenic activities during the nesting season, and management of nests to prevent them being destroyed by people. [ABSTRACT FROM AUTHOR]

Population numbers of the American crocodile in Colombia have shown an increasing trend during the last decades. However, the lack of monitoring programs has restricted our understanding about this species' ecology, limiting the ability to develop sound conservation plans. We assessed the effectiveness and robustness of the Individual Identification Pattern Recognition (IIPR) method for remotely monitoring American crocodile populations based on photographs taken by researchers, tourists, locals, and employees at the Tayrona National Natural Park (TNNP). We catalogued a total of 97 events from 2008 to 2020; 34.02% of which were suitable to analyze using IIPR. We identified eight individuals across 33 events that required only 4.71 ± 1.70 transverse scute lines to obtain complete identification, with the lowest levels of variation in the post occipital and nuchal regions compared with the dorsal area. The probabilities of repeating both the most and least common patterns found in the TNNP were 1.88 × 10−6 and 1.81 × 10−12, respectively, and the probabilities of repeating the same pattern of each individual identified ranged between 48.73 × 10−11 and 15.24 × 10−8. Animals B and C were continuously identified between 2012 and 2020 along the Arrecife beach coastline, whereas animals A, H, E, and F were occasionally registered between 2008 and 2019 at the Cañaveral beach. Overall, the IIPR method looks as a promising tool for monitoring American crocodile populations in the TNNP albeit some improvements in data collection that must be done to increase the number of useful events and analysis quality. [ABSTRACT FROM AUTHOR]

Two species of crocodilians have been described in Costa Rica, American crocodile, Crocodylus acutus (Cuvier, 1807), and caiman, Caiman crocodilus (Linnaeus 1758). In Costa Rica, data has been generated on both species, but populations in the Pacific have received more attention from researchers; presumably due to the fact that the Pacific slope has a greater development, which brings greater social pressure on the attention of the incidents generated by the encounter between humans and crocodiles. This study, performed during 2017, was done in an area of approximately 400 km2, characterized by having a wide and dense network of water courses, which includes the Matina, Pacuare, Reventazón and Parismina rivers. In these rivers, an average of 25 kilometers were traveled from the coastline up stream to the interior of the territory, including the Tortuguero canals, and other water bodies that connect these rivers, as well as in the most important lagoons and secondary channels. Three repetitions were made per segment. A population of 1 084 caimans and 503 crocodiles is estimated; for a sight count of 8.64 and 2.80 ind/Km respectively. Speaking of caimans, up to 12 % of individuals of reproductive age were observed, while for crocodiles that number was only 2 %. The abundance of both species in the different places studied, turned out to be significantly different for crocodiles and for caimans (Kruskal-Wallis, P ≤ 0.001). Likewise, the size distribution is similar for crocodiles reported in all environments (Kruskal-Wallis, p ≤ 0.15), while for caimans it indicates that there is a different distribution for sizes, according to the environment in which they are found (Kruskal -Wallis, P ≤ 0.001), with a bias against of the Pacuare and Matina rivers. It was possible to estimate a sex ratio of 1.25 and 0.83 males to females, in crocodiles and caimans respectively, with 9 and 11 captures in that same order, in recruit and juvenile sizes. [ABSTRACT FROM AUTHOR]

In recent years, the incidence of attacks by crocodiles in Costa Rica has increased, which is associated with the development of human activities in areas considered as optimal in what I determine as the species' potential habitat. Given the above, the present investigation proposes the identification of zones of interaction between the crocodile and the human being from the integration of physical-geographic variables through Geographic Information Systems (GIS). In this way, a theoretical compilation was carried out to identify the physical-geographical variables that make up the crocodile's habitat (slope, drainage network, flood areas and land use coverage), as well as the socio-environmental variables that influence the alteration and loss of habitat of the species (number of neighborhoods, population density, density of roads, and coverage of land use). Likewise, case records were integrated with crocodiles assisted by the fire department. It was possible to demonstrate that most of incidents occur in areas with high interaction (areas where a wide variety of anthropic activities are carried out within the potential habitat of this reptile.) In addition, the results obtained in the investigation constitute an important input in the decision-making at the policy and territorial order level in the Central Pacific Region, since tourism is one of the main economic activities that can be threatened by an attack by this species. [ABSTRACT FROM AUTHOR]

C. acutus is cataloged in critical danger in Colombia. We studied its population at Bahia Portete, in order to survey the nesting activities and to obtain valuable information for a conservation management program. This study was undertaken with the participation of the Wayuü community using the Agreement Conservation Model, and took place during July 2007, August 2008, June and August 2009, and March to August 2010 and 2011. Sampling surveys were made by the use of transects along the coast, in order to find nests. For each nesting area found, we recorded the nests biometrics, eggs and hatchlings, fertility of the eggs and reproductive events. We explored a total of 55.12 km, and determined four nesting areas. Colonial nesting and the environmental variables were factors that affected the hatchling success. From the total of nests found, 37% were oriented towards North, and 48% were built next to Stenocereus griseus. Juyui island substrate was mostly constituted by sand (71.9%, 71.44%). The average number of eggs by nest was 28.42 ± 6.63, the largest egg diameter was 71.84 ± 3.54 mm, the average nest weight was 81.54 ± 9.99 g, and the hatchlings presented an average length of 25.47 ± 1.16 cm. For this specific site in Colombia, the reproductive period begins in March and ends in August. The few areas of nesting and the 95% fertility suggest the performance of a conservation management program for this species at Bahía Portete. Rev. Biol. Trop. 65 (1): 211-228. Epub 2017 March 01. [ABSTRACT FROM AUTHOR]

The genetic variation in C. acutus from the Pacific coast of Mexico was investigated using mitochondrial DNA data. Overall, the localities sampled included three in the State of Guerrero and three in the State of Oaxaca, Mexico. We inferred phylogenetic and genealogical relationships, and genetic diversity was determined, using partial sequences of the mitochondrial control region. Additional published sequences from GenBank for C. acutus and C. moreletii were utilized. The results obtained from 73 crocodile sequences indicate the presence of five haplotypes grouped into two monophyletic lineages, one corresponding to C. acutus and the other to C. moreletii . The presence of C. moreletii in Chacahua (Oaxaca) was unexpected. The level of nucleotide diversity was nil and moderate in C. acutus and C. moreletii lineages, respectively, consistent with other publications concerning Crocodylia. Further studies of crocodiles in Chacahua (Oaxaca) are necessary to assess the possibility of hybridization. [ABSTRACT FROM AUTHOR]

Spatial variation in global climate change makes population-specific responses to this enigmatic threat pertinent on a regional scale. Organisms with temperature-dependent sex determination (TSD) potentially possess a unique physiological susceptibility that threatens population viability if rapid environmental effects on sex ratios render populations non-viable. A heavily male-biased sex ratio for hatchling American crocodiles of the Tempisque Basin, Costa Rica requires assessment of how nest temperature affects sex determination at this site, how females might compensate for these effects when creating nests, and how current patterns of climate change might alter future sex ratios and survival in hatchling cohorts. We demonstrate high within-nest variation in temperature but predict a female bias at hatching based on nest temperatures quantified here. Further, our data suggest that egg size and metabolic heating associated with this factor outweighs microhabitat parameters and depth in influencing nest thermal regimes. Finally, we document regional warming in the Tempisque Basin over the last 15 years and project that further heating over the next 15 years will not yield hatchling sex ratios as male biased as those currently found at this site. Thus, we find no support for nest temperature or climate change as likely explanations for male-biased American crocodile ( Crocodylus acutus ) sex ratios in the Tempisque Basin. [ABSTRACT FROM AUTHOR]

Nesting of the American crocodile (Crocodylus acutus) is affected by natural and anthropogenic processes. In Mexico, few studies exist on reproductive traits of wild populations. We assessed the key reproductive characteristics of C. acutus in the La Encrucijada biosphere reserve and the environmental and anthropogenic factors that influence them. From February to June 2014, we searched for nests in the reserve. Clutch incubation temperature was recorded by data loggers and climatic variables were obtained from La Encrucijada meteorological station. Additionally, outside the study area, net primary productivity was obtained for different sites in Mexico to relate it to clutch characteristics. We found 34 nests in nine nesting areas. Egg laying occurred in March, and hatching took place from mid-May to early June. Mean clutch and eggs characteristics are among the higher reported for C. acutus. Some egg attributes had a relationship with the net primary productivity. There was no relation between hatching success and external and internal characteristics of the nest. A high percentage of nests was poached (50%) mainly for egg consumption and fear of crocodiles, and the nests closer to the river, trees or human settlements are more likely to be poached. [ABSTRACT FROM AUTHOR]

Nesting is a part of the reproductive cycle of crocodiles with the greatest impact on the survival of the species, so the objective of this study was to describe ecological aspects of the American crocodile (Crocodylus acutus)nesting off the coast of Oaxaca, Mexico Nine nests from two localities (La Ventanillan= 6; Palmasola n = 3) were evaluated. Field records included oviposition and hatching dates, external (distance from the center of the nest to the nearest tree and water's edge, canopy cover) and internal (depth of the top of the nest, depth and width of the eggs chamber, humidity and pH of the top eggs chamber) nest measurements and eggs characteristics (number, fertility, length, width and weight). A Mann-Whitney test was used to compare internal and external nest variables clutches fertility and clutch size between nesting sites. A nested linear model was used to compare mean values of width, length and weight of the eggs between nesting sites. External nest variables were not significantly different (p >0.05). For inside variables, we observed only one significant difference (p =0.04), for themeanpH at the top of the nest (6.71 vs 6.01). For egg's characteristics, means of width (4.60 vs 4.84), length (7.54 vs 7.66 cm) and weight (95.4 vs 104.4 g) of the eggs were significantly different between nesting sites. This study brings first data on nesting ecology of the American crocodile in Oaxaca and results obtained suggest a good reproductive status in the region. However, it is needed several years of data to increment the sample size and confirm the specie reproductive status. [ABSTRACT FROM AUTHOR]

The American crocodile, Crocodylus acutus, is widely distributed in the American neotropics. It is endangered throughout most of its range and is listed as vulnerable by the International Union for the Conservation of Natural Fauna and Flora (IUCN) and on Appendix I of the Convention for the International Trade in Endangered Species of Wild Flora and Fauna (CITES). Despite this listing, there are few published reports on population status throughout most of its range. We investigated the status of the C. acutus, at several locations along the Pacific coast of Costa Rica. We carried out spotlight and nesting surveys from 2007-2009 along the Costa Rican Pacific coast in four distinct areas, coastal areas of Las Baulas (N=40) and Santa Rosa (N=9) National Parks and the Osa Conservation Area (N=13), and upriver in Palo Verde National Park (N=11). We recorded crocodile locations and standard environmental data at each observation. Encounter rates, population structure, distribution within each area and data on successful nesting (presence of hatchlings, nests, etc) were determined. We attempted to capture all crocodiles to record standard morphometrics. A total of 586 crocodiles were observed along 185.8km of survey route. The majority of animals encountered (54.9%) were either hatchlings (<0.5m) or juveniles (0.5-1.25m). The average non-hatchling encounter rate per survey for the Pacific coast was 3.1 crocodiles/km, with individual encounter rates ranging from 1.2 crocodiles/km to 4.3 crocodiles/ km in Las Baulas National Park and the Osa Conservation Area respectively. Distribution of size classes within the individual locations did not differ with the exception of Santa Rosa and Las Baulas National Parks, where hatchlings were found in water with lower salinities. These were the first systematic surveys in several of the areas studied and additional work is needed to further characterize the American crocodile population in Costa Rica. [ABSTRACT FROM AUTHOR]

Abstract: Crocodilians have temperature-dependent sex determination (TSD) in which incubation temperature determines sex of embryo. Global warming is expected to alter hatchling sex ratio, leading to the extinction of small populations. Regional climate influence on crocodile nest microclimate and hatchlings'' characteristics is poorly known. Here, microclimate in natural nests of American crocodile (Crocodylus acutus) and its relation with incubation length, hatchling sex and nesting success was studied in Banco Chinchorro Biosphere Reserve (Mexico) from 2007 to 2010. Temperature and relative humidity in different locations within and outside the nests were registered by data loggers. Incident solar radiation above nest was calculated from hemispheric photographs. Incubation length, proportion of hatchling reaching complete development and hatchling sex were determined at hatching. Nest temperatures exhibited a cyclic daily fluctuation due to solar radiation, which is the major heat source for nests. Clutch temperature was relatively stable and its daily amplitude was negatively correlated with clutch depth and size. Rainfall was the major source of clutch temperature decrease. Clutch and metabolic temperatures increased significantly during incubation. A small sample size failed to demonstrate a statistical relationship between length of incubation and mean clutch temperature. Proportion of embryos reaching complete development depended on maximum and minimum clutch temperature, maximum daily amplitude of clutch temperature and maximum decrease in clutch temperature on a period ≤4 day. Results confirmed a Female–Male–Female TSD pattern for C. acutus, with 31 and 32.5°C as possible pivotal temperatures. Population and hatchling sex ratios were male-biased and fate of crocodiles of Banco Chinchorro could depend on the magnitude of temperature increase in the future. [Copyright &y& Elsevier]

The article presents a study which determines the sexual size dimorphism, size population, morphometrics, sex ratio, and biomass of Crocodylus (C.) acutus in the coastal zone of Belize. It mentions that the measurements obtained from the crocodiles captured during 1996-1998, 2002, and 2008-2009 include total length, snout-vent length (SVL), and dorsal cranial length (DCL). It notes that the sexual size dimorphism index (SDI) for C. acutus was 2.10. It adds that the C. acutus in coastal Belize seem to have a smaller body size than those reported populations.

Abstract: We report complete mitochondrial genomic sequences for Crocodylus acutus and Crocodylus novaeguineae, whose gene orders match those of other crocodilians. Phylogenetic analyses based on the sequences of 12 mitochondrial protein-coding genes support monophyly of two crocodilian taxonomic families, Alligatoridae (genera Alligator, Caiman, and Paleosuchus) and Crocodylidae (genera Crocodylus, Gavialis, Mecistops, Osteolaemus, and Tomistoma). Our results are consistent with monophyly of all crocodilian genera. Within Alligatoridae, genus Alligator is the sister taxon of a clade comprising Caiman and Paleosuchus. Within Crocodylidae, the basal phylogenetic split separates a clade comprising Gavialis and Tomistoma from a clade comprising Crocodylus, Mecistops, and Osteolaemus. Mecistops and Osteolaemus form the sister taxon to Crocodylus. Within Crocodylus, we sampled five Indopacific species, whose phylogenetic ordering is ((C. mindorensis, C. novaeguineae), (C. porosus, (C. siamensis, C. palustris))). The African species C. niloticus and New World species C. acutus form the sister taxon to the Indopacific species, although our sampling lacks three other New World species and an Australian species of Crocodylus. [Copyright &y& Elsevier]

Abstract: Incubation of unsensitized sheep red blood cells with serum from the American crocodile (Crocodylus acutus) resulted in a concentration-dependent hemolysis. The hemolytic activity was heat-sensitive, and inhibited by EDTA in a concentration-dependent manner. The EDTA-inhibited SRBC hemolysis could be restored by the addition of excess Ca2+ or Mg2+, but not Ba2+ or Cu2+, revealing the specificity of this activity for these two divalent cations. The hemolytic activity of crocodile serum was titer-dependent, with 329μL producing 50% of maximal SRBC hemolysis. The complement activity was also temperature-dependent, with decreased activity at lower temperatures (5–15°C) and maximal activity occurred at 30–40°C. The hemolysis occurred relatively slowly, with near zero activity after 10min, 40% of activity observed within 15min of exposure to SRBCs, and maximal activity at 30min. [Copyright &y& Elsevier]

The post-occipital and nucal scutellation patterns of 111 crocodiles (Crocodylus acutus) from La Ventanilla, Oaxaca were analyzed. Thirty three different scutellation patterns were found. The most frequently observed pattern (31.5%) was 4 post-occipital scales present 2 external previous nucal scales absent, and 2 posterior nucal scales present (4-2EE-2). The pattern considered typical for this species was observed only in 6.31% of individuals. There were differences between the frequency distribution of common patterns when compared to other studies on C. acutus. [ABSTRACT FROM AUTHOR]

An experiment was designed with 90 neonates of the American crocodile, Crocodylus acutus, that were raised and fed with a standard diet during 50 days and with two experimental diets for 30 days, in three groups (A, B, C) kept in experimental square tanks during 30 days at the Manzanillo Zoocriadero (Province of Granma). The influence on size and body weight increase of two types of diets against the standard diet in C. acutus was analyzed, as well as the economic costs associated. The sea fish diet (B) is more effective compared to the standard diet of fish, cow liver and lung (A) and to the fly maggot diet (C), since the growth rate of neonates was 35 mm /day, growing 1.35 times more. The weight increase was 3.71 g/day, higher than the increases obtained with the other two diets. It was demonstrated that with diet B neonates grew 1.35 times more than with the diets A and C. However, each neonate fed with diet B costs 14 times more than those fed with the other two diets. [ABSTRACT FROM AUTHOR]

Between January and September 2006, 21 crocodiles (Crocodylus acutus) were captured and six were recaptured in four lagoons located in the southern coast of Quintana Roo. Stomach contents were obtained in order to identify prey items, which were analyzed by the frequency and volume method. In decreasing order of importance, prey items were fish, crustaceans, birds, mammals and insects. Diet of crocodiles changed considerably according to their body size. Adult crocodiles added larger preys (birds and mammals) to their diet; fish and crustaceans were present in the diet at all sizes, thus showing the importance of these prey in the diet of American crocodiles. [ABSTRACT FROM AUTHOR]

The crocodylid Crocodylus acutus is found in the Central Pacific of Costa Rica only in small populations, and the species is protected by law. RAPD was used to analyze 70 DNA samples of Crocodylus acutus from the rivers Jesus Maria, Tarcoles and Tusubres in the Central Pacific of Costa Rica in order to estimate genetic diversity, differentiation among populations, gene flow and genetic distance between them. Genetic diversity was low in the three rivers, H = 0.2201 in the Jesus Maria river, 0.2358 in the Tarcoles river and 0.2589 in the Tusubres river. Among the three populations there is a metapopulational dynamic (GST = 0.0367), mainly between the populations of the Jesus Maria and Tarcoles rivers. The value of gene flow (Nm = 13.1361) and the number of individuals reported for each river in 2004 suggests that the population of the Tarcoles river is the source and those from Jesus Maria and Tusubres are the drains. There was a direct relationship between the genetic distance and the geographical distance (z =1.1449, r =0.9731, p< 0.0010). A conservation strategy for these crocodiles must consider the existence of the metapopulation between the three rivers and the importance of studying the genetics of the American Crocodile in the rest of the Pacific coast of Costa Rica, as well as over the entire distribution range of this species. [ABSTRACT FROM AUTHOR]

A population of the American crocodile (Crocodylus acutus) protected through local participation was studied at La Ventanilla estuary in the coast of Oaxaca, during 8 months (October 2003-May 2004). Size, structure and sex ratio of this population were evaluated in order to provide demographic information of the American crocodile using two capture-recapture methods. A total of 21 adults (8 females, 13 males), 11 subadults (5 females, 6 males), 88 juveniles (14 females, 62 males) and 23 neonates were captured, measured and individually marked. Goodness-of-fit tests for the Jolly-Seber model showed that our population data violated the assumption of equal probability of capture and resulted in a skewed estimate of population size. However, goodness-of- fit tests for the geometric estimator of the capture frequency model applied to the same capture-recapture data showed recapture frequencies conform to it. Population size estimates for this model were 29.6 ± 9.1 adults, 37.1 ± 6.6 subadults, and 682.5 ± 39.2 juveniles. Population structure does not fit the normal distribution (d=39.5, P>0.05), most individuals belonging to lower size classes (16.2% in class I, 61.5% in class II), with few subadults (9.1% in class III) and adults (13.3 %, I class IV). Overall sex ratio was significantly skewed towards males (3 males: 1 female). This analysis provides information for future management strategies for the C. acutus population at La Ventanilla estuary. [ABSTRACT FROM AUTHOR]

During the months of October and November 2000, eight samples were made, at the Station Experimental La Rambla, which is locatated in Rio Frío de Sarapiquí, in Heredia. It was determinate that crocodiles are much more active during night time, and that the number of crocodiles that were seen has been affected with previous climate conditions. Different statistic methods were compared, to calculate the visible fraction, and conclude that there are no difference between the methods, and the visible fraction calculated based on the real captive population. [ABSTRACT FROM AUTHOR]

The nesting ecology of the American crocodile (Crocodylus acutus) was studied in the region of the Cuitzmala river mouth in Jalisco State, Mexico, from 1990 to 1993. Nesting occurred from mid-April to May, during the annual dry season, coinciding with high daily temperature variations. The initiation of nesting also appeared to be related to the presence of a new moon. Compared to other sites along the Pacific coast of the Americas, C. acutus in Jalisco nests late in the year, and timing of nesting appears to be related to latitude. Populations of C. acutus along the Gulf of Mexico and Caribbean show a similar latitudinal pattern. Females exhibit a tendency to nest fidelity. Total length of the smallest nesting female was estimated to be 225 cm, and largest was 305 cm. Nests were holes excavated in sand, sand-lime, or sand-lime-clay soils and percent of soil moisture ranged from 0.48% to 25.58%, with pH close to neutrality. Nests in sandy soils tended to have lower soil moisture levels and higher temperatures. Most nests faced south, and vegetation cover ranged from 0% to 30%. Clutch size ranged from nine to 54 (mean 27.9 ± 13.2). Overall egg viability was 80.7 ± 21.0%. It was found that larger females tend to have larger and heavier eggs, higher egg viability and natality. Hatching takes place during the annual rainy season. [ABSTRACT FROM AUTHOR]

Abstract: Temperature affects growth rate of crocodiles. However, no information exists about the effects of temperature by El Niño-South Oscillation (ENSO) on crocodiles. In this paper, we present information about the effect of ENSO on total length and body mass of Crocodylus acutus in captivity during 1997–2001. We did not observe differences in total length among years, but we did so in body mass. Furthermore, we observed that warm episodes of ENSO were associated with a higher average total length and cold episodes represented a higher average of body mass. Sea surface temperature (SST) was significantly related with total length; however, the relationship between SST and body mass was unclear. We suggest that ENSO effects on growth rates of crocodiles need to be considered as an important factor on the management of captive populations. [Copyright &y& Elsevier]

In order to assess the actual status of the Crocodylus acutus populations from northern Perú, Tumbes Region, from June 2002 to February 2003, diurnal and nocturnal surveys were conducted. A density of 0.19 indviduals / km was estimated. This is the lowest density for C. acutus worldwide. The following population structure was found: 82.61% juveniles, 4.37% subadults and 13.09% adults. This is similar to population structures reported elsewhere. [ABSTRACT FROM AUTHOR]