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The genusCrocodyluscomprises 12 currently recognized species, many of which can be difficult to differentiate phenotypically. Interspecific hybridization among crocodiles is known to occur in captivity and has been documented between some species in the wild. The identification of hybrid individuals is of importance for management and monitoring of crocodilians, many of which are Convention on International Trade in Endangered Species (CITES) listed. In this study, both mitochondrial and nuclear DNA markers were evaluated for their use in confirming a suspected hybrid zone between American crocodile (Crocodylus acutus) and Morelet’s crocodile (Crocodylus moreletii) populations in southern Belize where individuals and nests exhibiting atypical phenotypic features had previously been observed. Patterns observed in both phenotypic and molecular data indicate possible behavioural and ecological characteristics associated with hybridization events. The results of the combined analyses found that the majority of suspected hybrid samples represent crosses between femaleC. acutusand maleC. moreletii. Phenotypic data could statistically identify hybrids, although morphological overlap between hybrids andC. moreletiireduced reliability of identification based solely on field characters. Ecologically,C. acutuswas exclusively found in saline waters, whereas hybrids andC. moreletiiwere largely absent in these conditions. A hypothesized correlation between unidirectional hybridization and destruction ofC. acutusbreeding habitats warrants additional research.

Resumen en español: "Esta investigación tuvo como objetivo principal determinar y evaluar la condición corporal del cocodrilo americano (Crocodylus acutus) en cuatro lagunas costeras del Parque Nacional Arrecifes de Xcalak, Quintana Roo, México. Se utilizó la relación pesoperímetro de la base de la cola para aplicar el factor de condición de Fulton a los datos de 44 cocodrilos obtenidos a partir de una base de datos de 2006 (n = 26) y muestreos en 2012 (n = 18). Se analizó la condición corporal por periodo (2006 vs 2012), sitio de muestreo, clase de talla, sexo, salinidad, temperatura del agua y temporada climática. En general, C. acutus presentó una buena condición corporal (K = 2.57 ± 0.66), sin variaciones significativas entre periodos. Se encontraron diferencias significativas entre sexos (2006) y temporadas climáticas (2012). las hembras y los individuos capturados durante la temporada seca tuvieron los valores más altos de K. Además, para 2012, se obtuvieron datos de la composición de la dieta y helmintofauna gastrointestinal de los individuos capturados. Los datos de estas últimas dos variables se correlacionaron con la condición corporal para indagar posibles efectos; no se obtuvieron resultados significativos al respecto debido al número de muestras limitado. La composición de la dieta mostró que los peces fueron el grupo de presa mas consumido. Se encontraron diferencias significativas en el volumen relativo del contenido estomacal en las clases III (jóvenes) y V (adultos), así como entre sexos. La clase III y los machos presentaron las dietas más variadas. Respecto a la helmintofauna gastrointestinal, se identificaron tres especies: Dujardinascaris helicina, Terranova crocodili y Contracaecum sp. tipo 2; ésta última presentó la mayor abundancia (1.94 ± 0.29) y prevalencia (38.8%). Se observaron diferencias significativas en la frecuencia de aparición de la helmintofauna gastrointestinal; Contracaecum sp. tipo 2 fue la más frecuente para la clase III y los machos. El presente trabajo, aporta información de línea base, que puede ayudar al manejo y conservación de C. acutus. "

We recovered Pleistocene fossils from a lava-dammed river deposit along the Rio de Moctezuma in northeastern Sonora, at 29°41′N, 109°39′W, and 605 m elevation. Today the region is semiarid, with a foothills thornscrub community. The impoundment that resulted from the lava dam produced a short-lived marsh with an adjacent savanna. The extraordinary fauna is both diverse and rich, and includes ostracods, mollusks, fish, amphibians, turtles, a crocodilian, snakes, lizards, birds, and mammals, many with tropical affinities today. Most of the animals are either extralimital to the setting today or extinct. The recovery of Bison dictates a Rancholabrean Land Mammal Age for the fauna; a preliminary 40Ar/39Ar age suggests that the deposit is between 570,000 and 310,000 years old. The occurrence of cf. Crocodylus acutus (a crocodilian; generic assignment uncertain) and Pampatherium, the giant armadillo, is unique in the northern interior Sonora setting. We speculate that a well-developed riparian corridor...

The American crocodile is widely distributed in coastal and lowland wetlands in the northern Neotropics. As a result of commercial skin hunting in the 20th century, populations were greatly diminished, but in many areas have initiated a period of recovery since hunting and trade controls were enacted in the 1980s and 1990s. While a great deal of attention has been devoted to regulated commercial use as a management strategy for recovering crocodilian populations, these approaches are limited in their efficacy to deal with issues of habitat loss and fragmentation. Because habitat limitations are expected to be the most critical issue for crocodile conservation in the 21st century, there is an unfulfilled need for alternative strategies that prioritize habitat conservation. Here, we present results of an international effort to identify and prioritize the most critical habitats for this wide ranging species. We quantified information of a group of American crocodile experts and classified 69 areas in eight distinct crocodile bioregions as Crocodile Conservation Units (CCU), the most important areas for the conservation of this species. The relative importance of the CCUs in each bioregion was quantified using an algorithm that weighted factors that the experts considered to be most important for the long term conservation of viable populations of crocodiles. This effort is the initial step in the development of a regional conservation plan for the American crocodile. We identified two bioregions in particular where the creation of protected areas should be given a high priority, the Dry Pacific South America (northern Peru and southern Ecuador) and the Northwest and Central Pacific Mexico.

The discovery of an Early-Middle Pleistocene continental vertebrate fauna from El Salvador is here reported. These fossils provide information about a poorly studied geographic area that played an important role during the Great American Faunal Interchange. The fauna is dominated by numerous remains of the proboscidean Cuvieronius tropicus and probably represents the largest known concentration of this genus in America. A number of living taxa are first recorded as fossils in El Salvador, including Crocodylus acutus, previously unknown as a fossil elsewhere. Hesperotestudo crassiscutata, Glyptotherium arizonae, Palaeolama, Hemiauchenia cf. H. seymourensis and Equus conversidens, are recorded for the first time in Central America. The new locality also holds the oldest record of Mazama, and the southernmost records of Glyptotherium arizonae and Equus conversidens. At least 17 taxa are represented in the new site, constituting the richest Central American continental vertebrate locality hitherto known.

Durante los años 2001 y 2002 se realizaron observaciones sobre la reproducción de Crocodylus acutus (Cuvier, 1807) en el Centro de Acuicultura La Tuna Carranza, localizado en Puerto Pizarro, departamento de Tumbes. El tamaño mínimo de una hembra anidando fue de 2,30 m. El porcentaje de viabilidad y natalidad fue de 61,71% y 93,15% respectivamente.

Examinations of both population genetic structure and the processes that lead to such structure in crocodilians have been initiated in several species in response to a call by the IUCN Crocodile Specialist Group. A recent study used microsatellite markers to characterize Morelet’s crocodile (Crocodylus moreletii) populations in north-central Belize and presented evidence for isolation by distance. To further investigate this hypothesis, we sequenced a portion of the mitochondrial control region for representative animals after including samples from additional locales in Belize, Guatemala and Mexico. While there is limited evidence of subdivision involving other locales, we found that most of the differentiation among populations of C. moreletii can be attributed to animals collected from a single locale in Belize, Banana Bank Lagoon. Furthermore, mitochondrial DNA sequence analysis showed that animals from this and certain other locales display a haplotype characteristic of the American crocodile, C. acutus, rather than C. moreletii .W e interpret this as evidence of hybridization between the two species and comment on how these new data have influenced our interpretation of previous findings. We also find very low levels of nucleotide diversity in C. moreletii haplotypes and provide evidence for a low rate of substitution in the crocodilian mitochondrial control region. Finally, the conservation implications of these findings are discussed.

Everglades restoration will alter the hydrology of South Florida, affecting both water depth and salinity levels in the southern fringes of the Everglades, the habitat of the endangered American crocodile (Crocodylus acutus). A key question is what the effects of these hydrologic changes will be on the crocodile population. Reliable predictions of the viability of endangered species under a variety of management scenarios are of vital importance in conservation ecology. Juvenile American crocodiles are thought to be sensitive to high salinity levels, suffering reduced mass, and potentially reduced survivorship and recruitment. This could negatively impact the population recovery. We addressed the management issue of how the crocodile population will respond to alterations in hydrology with a spatially explicit individual-based model. The model is designed to relate water levels, salinities, and dominant vegetation to crocodile distribution, abundance, population growth, individual growth, survival, nesting effort, and nesting success. Our analysis shows that Everglades restoration, through its effects on water flow to estuaries, may benefit crocodile populations if increased freshwater flow reduces the chance that regional salinity levels exceed levels where small individuals lose mass. In addition, we conclude that conservation priority should be placed on reducing anthropogenic sources of mortality on large individuals, such as road mortality. Finally, research should focus on estimates of annual survivorship for large individuals. [KEYWORDS: Everglades restoration; Simulation model; American crocodile; Uncertainty analysis; Individual-based model]

Se estudió la ecología de la anidación del Cocodrilo Americano (Crocodylus acutus) en la desembocadura del Río Cuitzmala en la costa de Jalisco, México, en las temporadas de 1990 a 1993. La temporada de anidación es durante los meses de abril y mayo. Al analizar los datos compilados por otros autores y los de este estudio, se observa una tendencia latitudinal en el inicio de la anidación, siendo más temprana a bajas latitudes y más tardía a altas latitudes. Este mismo patrón puede ser aplicado a C. acutus de las vertientes del Golfo de México y el Caribe. La temporada de anidación en el área de estudio se presenta durante los meses más secos del año y es cuando la oscilación térmica diaria promedio de mínimas y máximas varía entre 15°C y 38°C en enero y entre 14°C y 35°C previo al inicio de la anidación en marzo; la fase de luna nueva parece coincidir con la excavación de los primeros nidos. Aparentemente existe fidelidad de las hembras por el nido. La hembra más pequeña midió 225 cm de longitud total, mientras que las más grandes midieron 305 cm. Los nidos fueron hoyos excavados en el substrato, orientados en su mayoría al sur, con suelos de pH cercanos a la neutralidad y con textura arenosa, areno-limosos y areno-limo-arcillosos y con una humedad entre 0.48 y 25.58%. Existe menor porcentaje de humedad y temperaturas más bajas en los nidos arenosos que en los nidos con un porcentaje mayor de limos y arcillas, que son significativamente más húmedos y con temperaturas mayores. La cobertura de la vegetación sobre los nidos estaba entre cero y 30%. El número de huevos por nido fluctuó entre nueve y 54 (promedio 27.9 ± 13.2). La viabilidad de los huevos promedió 80.7 ± 21.0. Existe una tendencia a que las hembras más grandes presenten huevos con mayor longitud y peso, con alta natalidad y viabilidad. El promedio de días de incubación fue de 83. Hay una tendencia a que los huevos con mayor longitud y peso, muestren una alta natalidad y viabilidad en las hembras más grandes, así como que los nacimientos ocurran a principios o durante la temporada de lluvias.

The secretion of the paracloacal glands of the American crocodile (Crocodylus acutus) contains over 80 lipophilic compounds, including saturated and unsaturated long-chain alcohols along with their formic, acetic, and butyric acid esters, and several isoprenoids. Most of these compounds were identified on the basis of mass spectra, obtained by GC-MS. In addition, identification of the major components was supported by infrared spectra obtained by GC-FTIR. Major differences are indicated in the composition of the paracloacal gland secretion of C. acutus and that of another crocodylid, the African dwarf crocodile (Osteolaemus tetraspis).

Organochlorine (OC) residues were recently detected in nonviable Morelet's crocodile (Crocodylus moreletii) eggs from northern Belize. To further the assessment of contaminant exposure in Belizean crocodiles, nonviable Morelet's crocodile eggs (n = 11) from southern Belize and American crocodile (Crocodylus acutus) eggs (n = 12) from the coastal zones of Belize were screened for 20 OCs. Results indicated p,p-DDE to be the most prevalent OC (96% occurrence) in eggs examined, with concentrations ranging from 5 to 372 ng/g. These concentrations are similar to those observed in crocodile eggs (10-180 ng/g) from northern Belize. A general trend toward higher DDE concentrations in Morelet's crocodile eggs (mean = 103 ppb) compared with American crocodile eggs (mean = 31 ppb) was observed. However, this trend may be due to site-specific contamination rather than differences in interspecific susceptibility to chemical exposure. Other OCs detected in crocodile eggs included the parent compound, p,p-DDT, and its metabolite, p, p-DDD.

The status of the American crocodile (Crocodylus acutus) in the coastal zone of Belize was investigated from July 1996 to October 1997. Two hundred and sixty-two crocodiles were observed during spotlight surveys of 952.2 km of the survey route (0.28 crocodiles/km). Encounter rates were highest in the TurneAe Atoll, and low to moderate elsewhere. Most nesting occurs on elevated beach ridges in the TurneAe Atoll. Freshwater and brackish lagoons adjacent to nesting sites provide essential nursery habitat. Despite legal protection, populations are threatened by opportunistic killing, accidental drowning in fishing nets, and habitat destruction, especially the development of critical nesting habitat. Protection of nesting and nursery habitat is of paramount importance for the continued survival of the American crocodile in Belize. # 2000 Elsevier Science Ltd. All rights reserved.

We conducted a study of American Crocodile nesting ecology in coastal Belize from June 1996 to July 1997. Most nesting areas were found on elevated beach ridges composed of coarse sand. Shallow, brackish lagoons adjacent to nesting areas provide critical nursery habitat for hatchlings. The most significant nesting areas were found in the Turneffe Atoll. American crocodiles construct both hole and mound nests in Belize. Clutches are deposited during the last half of the dry season, from late March to early May. Mean clutch size is 22.3 ± 6.0 eggs. Hatching occurred from late June to mid-July, a period coinciding with the beginning of the wet season. Nesting success was high, and losses to predation and flooding were negligible. Females may defend nests from predators and excavate neonates at hatching, but otherwise parental care appears minimal. The protection of suitable nesting and nursery habitat is essential for the continued survival of the American crocodile in Belize.

Temperature affects growth rate of crocodiles. However, no information exists about the effects of temperature by El Nino-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.

El objetivo del estudio fue determinar el perfil bioquímico renal del cocodrilo de Tumbes (Crocodylus acutus) criado en cautiverio en Tumbes, Perú. Los animales fueron contenidos mediante sujeción manual y se colectaron muestras de sangre (6 ml) mediante punción del seno venoso post-occipital a 60 animales machos (24 juveniles, 27 subadultos y 9 adultos). El valor de ácido úrico fue de 74.2 ± 25.0 mg/L, creatinina: 1.49 ± 0.39 mg/L, calcio: 10.8 ± 2.4 mg/dl y fósforo: de 5.3 ± 2.0 mg/dl. Se encontró diferencia estadística (p, The aim of the study was to determine the biochemistry profile of the kidney in the Tumbes crocodile (Crocodylus acutus) reared in captivity in the north of Peru (Tumbes). Blood samples (6 ml) by puncture of the post-occipital venous sinus were collected to 60 males (24 juveniles, 27 sub-adults, and 9 adults). All animals were manually restrained. Values for uric acid was 74.2 ± 25.0 mg/L, creatinine 1.49 ± 0.39 mg/L, calcium 10.8 ± 2.4 mg/dl, and phosphorus 5.3 ± 2.0 mg/dl. There was significant difference (p

Animal dispersal is the movement outward from a home area. This brief communication describes the movement of an adult and a juvenile of Crocodylus acutus captured and recaptured in the locality of Puerto Vallarta, Mexico, between 2001 and 2004. Between capture and recapture, the adult crocodile moved 5 km in lapse of 42 days and a juvenile crocodile moved 1.6 km in lapse of three years and five months.

Perception and popular culture about the crocodile (Crocodylus acutus) near Tempisque River, Guanacaste, Costa Rica. The American crocodile (Crocodylus acutus) is an endangered species due to habitat loss and illegal hunting. Its population has recovered significantly in the Tempisque River, Costa Rica; nevertheless, they are still vulnerable because their niche and habitat overlap human activities, which causes a human-crocodile conflict worsened by mistaken popular beliefs. We evaluated popular perception and knowledge with 336 surveys in 11 towns of Carrillo, Santa Cruz and Cañas, in Guanacaste. We also tested the relationships among residence, occupation, sex, age and educational grade and perception of danger. The inhabitants believe there is an excess of crocodiles near their towns, and the reptiles are considered dangerous and aggressive. Overall, they know little about the biology of C. acutus, but much about its behavior, conservation status and state protection. To regulate the crocodile population, they consider elimination or relocation necessary (both have different implications). They seem, however, willing to cooperate in management plans. It is important to choose key towns to strengthen existent environmental education programs with contents about the biology of the species, security, and conflict avoidance. In the near future, we recommend the establishment of a management plan to regulate crocodile population in some specific spots within the Tempisque River’s Basin. El cocodrilo americano (Crocodylus acutus) es una especie amenazada por la pérdida de hábitat y la caza ilegal. En el río Tempisque, Costa Rica, sus poblaciones se han recuperado considerablemente pero siguen siendo vulnerables porque su nicho y hábitat se traslapan con las actividades humanas, lo que genera un conflicto humano-cocodrilo (CHC) que se agrava por conocimientos populares erróneos. Este trabajo evalúa la percepción y el conocimiento popular sobre los cocodrilos mediante 336 encuestas en 11 pueblos de los cantones Carrillo, Santa Cruz y Cañas de Guanacaste. Además se analizó la relación entre la percepción de peligrosidad de los cocodrilos según el pueblo de residencia, la edad, el sexo, el grado académico y la ocupación de los encuestados. La población considera que en sus pueblos existen demasiados cocodrilos, que son peligrosos y agresivos. En general conocen poco sobre la biología de C. acutus, pero bastante sobre su comportamiento, estado de conservación y protección estatal. Las personas encuestadas creen necesario regular las poblaciones de cocodrilos, sugieren la eliminación o el traslado selectivo (las cuales tienen diversas implicaciones) y parecen dispuestos a cooperar en planes de manejo. Se insta a seleccionar pueblos clave para reforzar los programas de educación ambiental con contenidos sobre la biología de la especie, seguridad y prevención de CHC. A futuro, parece necesario establecer un plan de manejo para regular las poblaciones de cocodrilos en algunos sitios específicos de la cuenca del río Tempisque. Universidad Nacional, Costa Rica Escuela de Ciencias Biológicas

Se realizaron un total de 8 muestreos durante los meses de Octubre y Noviembre de 2000, en La Estación Experimental La Rambla ubicada en Río Frío de Sarapiquí en la provincia de Heredia, Costa Rica. Se determinó que los cocodrilos presentan un pico de actividad durante la noche, y que el número de cocodrilos observados se ve afectado por condiciones climáticas previas y durante los muestreos. Se comparó los diferentes métodos estadísticos para calcular la fracción visible, determinando que no existen diferencias entre los métodos y la fracción visible calculada en base al tamaño real de la población cautiva. 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.

De Junio del 2002 a Febrero del 2003, se han realizado recorridos en la zona norte de Perú, específicamente en la región de Tumbes, para conocer el estado actual de Crocodylus acutus, mediante recorridos diurnos y nocturnos, estimando una densidad de 0.18 ind/Km siendo una de las densidades más bajas de C. acutus en su ámbito de distribución. La estructura poblacional es de 82.61% juveniles, 4.35% de sub-adultos y 13.04% de adultos, siendo similar a lo reportado en otras poblaciones. 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.

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, popula- tion 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 croco- diles were observed along 185.8km of survey route. The majority of animals encountered (54.9%) were either hatchlings (

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.

Se documentan dos casos clínicos observados en ejemplares juveniles de cocodrilo de río (Crocodylus acutus) en cautiverio dentro de las instalaciones de la UMA “Reptilario Cipactli” de la Universidad de Guadalajara, campus Puerto Vallarta, Jalisco. Ambos organismos fueron capturados dentro del estero “Boca Negra”, localizado en la porción norte de la ciudad de Puerto Vallarta.

Among crocodilians, Crocodylus rhombifer is one of the world's most endangered species with the smallest natural distribution. In Cuba, this endemic species coexists with the American crocodile (Crocodylus acutus). Hybridization between these two species is well known in captivity and might occur in the wild, but has never been demonstrated genetically. Here, we combined molecular data with environmental, geographic, and fossil data to infer the evolutionary history of Crocodylus in the Cuban Archipelago, and to evaluate genealogical support for species boundaries. We analyzed seven microsatellite loci plus DNA sequence data from nuclear (RAG-1) and mitochondrial (cytochrome b and cytochrome oxidase I) genes from 89 wild-caught individuals in Cuba, Grand Cayman Island, Jamaica, and Central America, and two samples from zoo collections. Microsatellites showed evidence of introgression, suggesting potential hybridization among Cuban groups. In Cuba, C. acutus contained one mitochondrial DNA (mtDNA) haplotype, whereas C. rhombifer contained two haplotypes. MtDNA data showed that C. acutus is paraphyletic with respect to C. rhombifer, revealing 1% sequence divergence between species within Cuba vs. 8% divergence between Cuban forms and mainland C. acutus. We suggest that hybridization has been a historical as well as a current phenomenon between C. acutus and C. rhombifer. These findings suggest that long-term conservation of crocodiles in Cuba will require identification of genetically pure and hybrid individuals, and a decrease in anthropogenic activities. We also recommend more extensive morphological and genetic analyses of Cuban population to establish clear boundaries of the hybrid zone between C. acutus and C. rhombifer.

The purpose of this project was to characterize the genetic and morphological composition of Crocodylus acutus in Coiba Island, Panama, and to infer the population structure derived from the genetic variability between the North and South region of the Island as influenced by geographic barriers and proximity to continental Panama. Multivariate analysis of variance (MANOVA) was performed to analyze the morphometric measurements. The MANOVA for the effect of sample site indicate differences between locations (P = 0.010). Regarding morphometric variables, North and South of Coiba Island overlapped in the discriminant space, but individuals in Mainland were slightly separated from the South of Coiba Island. The analysis of molecular variance (AMOVA) reported a variation among populations of 17.04%, and within populations of 82.96% with an Fst of 0.17 (P < 0.01) implying genetic structure between the populations sampled. The Bayesian analysis based on a clustering method for inferring population structure confirmed the subdivision identifying the maximum likelihood in a K = 3. Geographic barriers influenced the genetic and morphometric variation in the populations of C. acutus in Coiba Island, as confirmed by the presence of three subdivisions, the absence of immigrants and the landscape heterogeneity in the Island. This genetic structure should be considered in conservation programs.

The present investigation was carried out with the purpose of evaluating the population of crocodylus acutus and its relationship with the human communities in the estuaries of the municipality of San Blas, Nayarit. During the years 2005 to 2009 the population dynamics and ecology of the crocodile were described, it was determined the sex of the crocodiles with three techniques, and the sociocultural appreciation of the crocodile for the community was described. To know the population ecology of the crocodile, samplings were carried out in the months of June 2005 and February 2006 (low water), as well as in October 2005 and October 2007 (rains). The method used was to make night trips in the estuaries, counting individuals per kilometer. Six transects were carried out covering a total of 89 km, of estuary channels and coastal lagoons in an area of 16,130 ha. La presente investigación se realizó con el fin de evaluar la población de crocodylus acutus y su relación con las comunidades humanas en los esteros del municipio de San Blas, Nayarit Durante los años 2005 al 2009 se describió la dinámica poblacional y ecología del cocodrilo, se determinó el sexo de los cocodrilos con tres técnicas, y se describió la apreciación sociocultural del cocodrilo par la comunidad. Para conocer la ecología poblacional del cocodrilo se realizaron muestreos en los meses de junio 2005 y febrero 2006 (estiaje), así como en octubre 2005 y octubre 2007 (lluvias). El método utilizado fue realizar recorridos nocturnos en los esteros, contabilizando individuos por kilómetro. Se realizaron 6 transectos recorriendo un total de 89 km, de canales de esteros y lagunas costeras en un área de 16,130 ha.

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.

Se presentan cinco casos de ataques por cocodrilos a personas, sin consecuencias fatales, en la region de Puerto Vallarta, Jalisco, Mexico (2007-2010). En cuatro de los casos, la victima sufrio amputacion del miembro superior o inferior, y en un caso solo resulto con mordeduras avulsivas en el brazo. Con la documentacion de estos cinco casos, el numero de ataques por cocodrilo americano (Crocodylus acutus) en la costa del estado mexicano de Jalisco durante los ultimos 52 anos es de entre 30 y 31. Los resultados muestran un incremento en los ataques entre 0,57 y 0,59 por ano. Se describen los casos y se proponen explicaciones sobre los posibles motivos de los ataques por parte de los cocodrilos.

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 329 microL producing 50% of maximal SRBC hemolysis. The complement activity was also temperature-dependent, with decreased activity at lower temperatures (5-15 degrees C) and maximal activity occurred at 30-40 degrees C. The hemolysis occurred relatively slowly, with near zero activity after 10 min, 40% of activity observed within 15 min of exposure to SRBCs, and maximal activity at 30 min.

Detecting and quantifying hybridization between endangered or threatened taxa can provide valuable information with regards to conservation and management strategies. Hybridization between members of the genus Crocodylus has been known to occur in captivity and in some wild populations. We tested for hybridization among wild populations of American crocodile (C. acutus) and Morelet's crocodile (C. moreletii) in the Yucatan Peninsula by comparing Bayesian assignment tests, based on microsatellite data, to mitochondrial and morphological assignments. Skin clips from 83 individuals were taken for genetic identification, and a total of 32 individuals (38.6%) exhibited some evidence of hybridization by combined morphological, mitochondrial and microsatellite analyses. The majority of hybrids were classified as F(2) hybrids and backcrosses to C. moreletii. Most of the introgression occurs in two national biosphere reserves located on the northern and eastern coasts of the Yucatan Peninsula. Preliminary tests did not find a significant decrease in hybridity across three life stages, thus far indicating a low level of selection against hybrids. Model-based analyses on multilocus genotypes of pure individuals returned little geographic partitioning in both C. acutus and C. moreletii.

There is a surprising lack of genetic data for the Cuban crocodile (Crocodylus rhombifer), especially given its status as a critically endangered species. Samples from captive individuals were used to genetically characterize this species in comparison with other New World crocodilians. Partial mitochondrial sequence data were generated from cyt-b (843 bp) and the tRNA(Pro)- tRNA(Phe)-D-loop region (442 bp). Phylogenetic analyses were performed by generating maximum parsimony, maximum likelihood, and Bayesian-based topologies. In addition, in an effort to identify species-specific alleles, ten polymorphic microsatellite loci were genotyped. Distance and model-based clustering analyses were performed on microsatellite data, in addition to a model-based assignment of hybrid types. Both mitochondrial and nuclear markers identified two distinct C. rhombifer genetic sub-clades (alpha and beta); and microsatellite analyses revealed that most admixed individuals were F(2) hybrids between C. rhombifer-alpha and the American crocodile (C. acutus). All individuals in the C. rhombifer-beta group were morphologically identified as C. acutus and formed a distinct genetic assemblage. J. Exp. Zool. 309A:649-660, 2008. (c) 2008 Wiley-Liss, Inc.

The American crocodile (Crocodylus acutus) and the Morelet's crocodile (C. moreletii) are broadly sympatric in Belize and Mexico. The presence of morphologically anomalous individuals in the overlapping range area suggests possible hybridization between these species. Analysis of 477 base pairs of the mitochondrial tRNAPro-tRNAPhe-Dloop region revealed the presence of pure C. acutus (N=43) and C. moreletii (N=56), as well as a high proportion of interspecific hybrids (N=17, 14.6%) in the Yucatan Peninsula, Mexico. Although all individuals could be assigned to one species or other based on phenotypic characters, some had been characterized as potential hybrids in the field by anomalous scale counts. The hybridization zone lies along the area of sympatry between C. acutus and C. moreletii investigated in this study, but extends further inland if hybrid localities from Belize are included. Hybridization in the Yucatan Peninsula is bidirectional, which indicates considerably more genetic contact between these species than previously recognized, and is probably more detrimental to the genetic integrity of smaller C. acutus populations. A more intensive study of the pattern of hybridization is warranted and supports continued classification of C. acutus as a critically threatened species in the Yucatan Peninsula. J. Exp. Zool. 309A:661–673, 2008. © 2008 Wiley-Liss, Inc.

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 theimportance of these prey in the diet of American crocodiles.

A group of 40 individuals of C. acutus by captive reproduction maintained in the Centro de Acuicultura La Tuna Carranza, localed en Puerto Pizarro, Departamento de Tumbes was used to evaluate the growth. Comparations between size class of crocodiles showed that growth in length are not different, but growth in weight are different. The mean growth in length and weight was 1,44% and 0,18% in hatchling, 1,30 and 0,10% in yearlings, 1,24 and 0,22% in juveniles, 1,24 and 0,48% in subadults, and 1,01 and 0,75% in adults. The growth rate of females was highest that males. Se evaluó el crecimiento en peso y longitud en 40 individuos del Cocodrilo de Tumbes en el Centro de Acuicultura La Tuna Carranza, localizado en Puerto Pizarro, Departamento de Tumbes. No se observó una diferencia en el incremento en longitud por clases de edad, mientras que en peso si presentaron diferencias siendo mayor en adultos. El crecimiento promedio de longitud y peso fue de 1,44% y 0,18% en crías, 1,30% y 0,10% en reclutas, 1,24 y 0,22% en juveniles, 1,24 y 0,48% en subadultos, y 1,01 y 0,75% en adultos. En general las hembras presentan un mayor crecimiento que los machos.

Dado el conocimiento que existe sobre la capacidad de movilización de Crocodylus acutus, se llevó a cabo una investigación a nivel genético para determinar si entre las poblaciones de cocodrilos de tres ríos del Pacífico central de Costa Rica se presenta una dinámica metapoblacional. Se obtuvo 70 muestras de ADN de los cocodrilos que habitan los ríos Jesús María, Tárcoles y Tusubres. Los resultados confirman la existencia de una dinámica metapoblacional tomando en cuenta los valores de diferenciación genética y distancia genética entre poblaciones además del flujo de genes. Este hallazgo sirve de base para tomar conciencia de que en el país deben de cambiarse las políticas sobre conservación y manejo de esta especie, ya que hasta el momento se han tratado como poblaciones independientes. Given the knowledge existing on the capacity of mobilization of Crocodylus acutus, an investigation was carried out at the genetic level to determine if exist a metapopulational dynamic between the populations of crocodiles from three rivers in the central pacific of Costa Rica. 70 DNA samples were obtained from the crocodiles inhabit the rivers Jesus Maria, Tarcoles and Tusubres. The results confirm the existence of a metapopulationall dynamics because the values from genetic differentiation and genetic distance between populations in addition to the gene flow. This finding serves as base to become aware that polices in the country about conservation and handling of this species must change, since until the moment it have treated like independent populations.

We assessed the reproductive ecology of the American crocodile (Crocodylus acutus) on Coiba Island, Panama from January–December 2013. We examined nest site characteristics from January–April and hatchling survivorship from April–December. Ten nests were examined at three nesting localities where 30% of the nests were found under forest canopies and 70% were exposed to sunlight (distance to nearest tree = 280 ± 110 cm). Half of the nests were built closer to the sea and the other half closer to bodies of freshwater (700 ± 360 cm). The nest dimensions were 17.5 ± 7.8 cm from the top of the clutch to the surface, 42.9 ± 9.9 cm from the bottom of the clutch to the surface, and 35.9 ± 3.6 cm wide at the top of the nest cavity. The average soil conditions in the nests consistently had high concentrations of potassium (69.3 mL/L) and manganese (9.2 mg/L), moderate concentrations of phosphorus (6.6 mg/L) and iron (3.7 mg/L), and low concentrations of zinc (0.5 mg/L) and copper (0.0 mL/L). Cation exchan...

Observations about reproduction of Crocodylus acutus (Cuvier, 1807) were recorded during the years 2001 and 2002 in the Fishery Center «La Tuna Carranza» (Puerto Pizarro, Tumbes, Peru). The minimum size of a female nesting was 2,30 m. The percentage of viability and birthrate/natality were 61,71% and 93,15%, respectively., Durante los años 2001 y 2002 se realizaron observaciones sobre la reproducción de Crocodylus acutus (Cuvier, 1807) en el Centro de Acuicultura La Tuna Carranza, localizado en Puerto Pizarro, departamento de Tumbes. El tamaño mínimo de una hembra anidando fue de 2,30 m. El porcentaje de viabilidad y natalidad fue de 61,71% y 93,15% respectivamente.

An assessment on the population ecology, distribution and habitat of the American crocodile (Crocodylus acutus) was conducted within the recent protected area ?Reserva de produccion de fauna manglares El Salado?, Gulf of Guayaquil, Ecuador. The study was developed along 15 km of mangrove channels and tidal creeks, using nocturnal spotlight boat surveys during the dry season (September to December, 2004). About four crocodiles, with a relative abundance of 0.45 ind./km, ranging 0.27?0.63 ind./km, were detected. Crocodiles were aggregated in the final extreme of a tidal creek (Estero Plano Seco), where the water salinity ranged 10.0?28.0 psu and releasing of effluents (>32.0°C) from electric power plants and run-off from urbanized centers have been evidenced. Most of the crocodile sightings occurred during low tide. The population was represented only by adults (50%) and juveniles (50%); subadults and hatchlings were not observed during the study period. The population density found in this study is one of the lowest densities for American crocodile in the American regions. The euryhaline ability and tolerance to inhabit elevated surface water temperature (thermoconformer) confirm the physiological adaptation of this reptile species. More ecologic and population studies are needed to elucidate some gaps and the environmental factors influencing on the species conservation, as well as the establishment of management strategies to ensure its survival.

In this paper, length and weigth measurements of 20 newborn Crocodylus acutus (Cuvier, 1807) hached in a pilot farm-bred of the aquaculture center La Tuna Carranza, Puerto Pizarro, Tumbes, Peru, in 2001 are presented. The information is compared with similar reports from others places., Se presentan las medidas de longitud y peso de 20 crías de Crocodylus acutus (Cuvier, 1807) recién nacidas en cautiverio en el zoocriadero piloto del Centro de Acuicultura La Tuna Carranza, Puerto Pizarro, Tumbes, Perú, en el año 2001. Esta información es comparada con la procedente de otros lugares para la misma especie.

Se presentan las medidas de longitud y peso de 20 crías de Crocodylus acutus (Cuvier, 1807) recién nacidas en cautiverio en el zoocriadero piloto del Centro de Acuicultura La Tuna Carranza, Puerto Pizarro, Tumbes, Perú, en el año 2001. Esta información es comparada con la procedente de otros lugares para la misma especie. In this paper, length and weigth measurements of 20 newborn Crocodylus acutus (Cuvier, 1807) hached in a pilot farm-bred of the aquaculture center La Tuna Carranza, Puerto Pizarro, Tumbes, Peru, in 2001 are presented. The information is compared with similar reports from others places.

The conservation status in Peru of the Tumbes Crocodile is described. This country is the southern limit of crocodile distribution and for that is catalogued as rare at this zone. This has been generating ex situ management programs to encourage its conservation. However, crocodile population have diminished and become endangered as consequence of deforestation, climatic change, the anthropogenic activities and the unknown uses it can provide., En esta nota se describe el estado de conservación del Cocodrilo de Tumbes en Perú, donde la especie encuentra su límite sur de distribución, por lo que es catalogada como especie rara en la zona. Esto ha generado que se lleven a cabo programas de manejo ex situ para apoyar su conservación. Sin embargo el desconocimiento de los beneficios que brinda la especie, junto con la deforestación, el cambio climático y las actividades antropogénicas, han ocasionado que su población disminuya y se encuentre amenazada.

Se estudió la ecología de la anidación del Cocodrilo Americano (Crocodylus acutus) en la desembocadura del Río Cuitzmala en la costa de Jalisco, México, en las temporadas de 1990 a 1993. La temporada de anidación es durante los meses de abril y mayo. Al analizar los datos compilados por otros autores y los de este estudio, se observa una tendencia latitudinal en el inicio de la anidación, siendo más temprana a bajas latitudes y más tardía a altas latitudes. Este mismo patrón puede ser aplicado a C. acutus de las vertientes del Golfo de México y el Caribe. La temporada de anidación en el área de estudio se presenta durante los meses más secos del año y es cuando la oscilación térmica diaria promedio de mínimas y máximas varía entre 15°C y 38°C en enero y entre 14°C y 35°C previo al inicio de la anidación en marzo; la fase de luna nueva parece coincidir con la excavación de los primeros nidos. Aparentemente existe fidelidad de las hembras por el nido. La hembra más pequeña midió 225 cm de longitud total, mientras que las más grandes midieron 305 cm. Los nidos fueron hoyos excavados en el substrato, orientados en su mayoría al sur, con suelos de pH cercanos a la neutralidad y con textura arenosa, areno-limosos y areno-limo-arcillosos y con una humedad entre 0.48 y 25.58%. Existe menor porcentaje de humedad y temperaturas más bajas en los nidos arenosos que en los nidos con un porcentaje mayor de limos y arcillas, que son significativamente más húmedos y con temperaturas mayores. La cobertura de la vegetación sobre los nidos estaba entre cero y 30%. El número de huevos por nido fluctuó entre nueve y 54 (promedio 27.9 ± 13.2). La viabilidad de los huevos promedió 80.7 ± 21.0. Existe una tendencia a que las hembras más grandes presenten huevos con mayor longitud y peso, con alta natalidad y viabilidad. El promedio de días de incubación fue de 83. Hay una tendencia a que los huevos con mayor longitud y peso, muestren una alta natalidad y viabilidad en las hembras más grandes, así como que los nacimientos ocurran a principios o durante la temporada de lluvias

Se revisaron 56 excretas de Crocodylus acutus recolectadas del medio natural entre junio de 1989 y mayo de 1993, en la Reserva Ecológica de Cuitzmala, en la costa del estado de Jalisco, México. Después de revisar los restos existentes en las excretas se obtuvieron los siguientes resultados: pelo de mamíferos 51.78 %, plumas de ave 32.14 %; restos de escamas de peces y reptiles 30.35 %, restos de crustáceos 26.78 %, insectos 12.50 % y semillas 21.42%. Aún cuando se ha señalado que los adultos de C. acutus son principalmente piscívoros, en las excretas revisadas para este trabajo los restos de escamas de peces fueron menos frecuentes en las excretas de mayor tamaño, que probablemente corresponden a cocodrilos adultos. Se encontraron representados en las excretas 15 grupos de organismos (incluyendo la observación de la ingesta directa de un pelícano) y se identificaron 10 nuevos registros de especies en la dieta de este cocodrilo. La presencia de semillas en el tubo digestivo de los cocodrilos es un hallazgo interesante, ya que es la primera vez que se registra, lo que sugiere que estos organismos actúan como diseminadores secundarios, teniendo más impacto en el ambiente de lo que se conoce hasta ahora. Los resultados permiten establecer similitudes en los hábitos de alimentación con los de Crocodylus niloticus, C. palustris y Alligator mississippiensis.

It was documented the perception towards river crocodiles ( Crocodylus acutus, Cuvier 1807 ) of two rural communities in the southwest Jalisco coast. Through semi-structured interviews, it was found that the perception towards the species is negative; 85% of interviewees considered it a dangerous animal because it attacks people and cattle. Results show that inhabitants perceive that due to protection activities, the crocodiles’ population size has increased. Attitudes of rejection lead to propose the elimination of crocodiles or that the owners of the Chamela-Cuixmala Biosphere Reserve look after them or lock them in. Some people mentioned the use of the animals as an alternative (55%). This study may contribute to the formulation of a strategy that promotes the conservation of the species through motivating changes in the perceptions, attitudes and valuation of the people that share the habitat with crocodiles. Environmental education actions are proposed that support these changes, at the same time that useful information is disseminated for the protection of people from possible attacks, as well as to evaluate possible economic uses of the species.

Resumen en español: "Entre abril y agosto de 1996, se obtuvieron índices de abundancia y distribución de los cocodrilianos nativos (Crocodylus acutus y Caiman crocodilus), se identificaron las características de la explotación pesquera y se evaluaron las interacciones entre los cocodrilianos y la pesca en el Sistema Lagunar Chantuto-Panzacola (18,000 ha), dentro de la Reserva de la Biosfera “La Encrucijada” en la costa de Chiapas, México. El Sistema Lagunar fue dividido en 3 localidades con 10 estaciones de muestreo. La mayor abundancia de caimanes (Caiman crocodilus) se presentó en la Localidad Chantuto (33.8 individuos/km) y la menor en la Localidad Panzacola (0.7 individuos/km). Los cocodrilos (Crocodylus acutus) únicamente se registraron en la Localidad El Hueyate, presentando los índices más altos 2.1 individuos/km y los más bajos 0.6 individuos/km. Se registraron en el Sistema Lagunar 744 pescadores activos durante todo el año, quienes capturan principalmente camarón (Penaeus stylostris y Penaeus vannamei), para lo cual utilizan atarrayas, trasmallos, tapos y chiqueros. La mayor intensidad pesquera fue registrada en las Localidades de Chantuto y Panzacola. Los principales factores de impacto sobre las poblaciones silvestres de cocodrilianos fueron fenómenos como la alta densidad de pescadores, la cacería de organismos, la pérdida o disminución de hábitat y la contaminación, más que las artes de pesca. Por otro lado, se registró que los cocodrilianos ocasionalmente rompen las artes de pesca al jalar los peces atrapados en las redes, algunas veces capturan animales domésticos y rara vez se registran ataques a humanos. " Resumen en inglés: "April to august 1996, we regestered relative abundance and distribution of native crocodilians (Crocodylus acutus y Caiman crocodilus), identified caracteristies of fishing practices and evaluated the relation between the crocodilians and fishery industry on the lagunar system Chantuto-Panzacola (18,000 ha). Biosphere Reserve “La Encrucijada” on the Chiapas coast of México. The lagunar system was divided in three locations with ten sample station. The greatest caiman (Caiman crocodilus) abundance was presented in the Chantuto location (33.8 ind/km) and the least in Panzacola (0.7 ind/km). Crocodiles (Crocodylus acutus) were only present in the El Hueyate location, with high index of 2.1 ind/km and low index of 0,6 ind/km. We registered 744 active fishermen. They catch principly shrimp (Peneaus stylostns and Peneaus vannamei), with atanayas, trasmallos, tapos y chiqueros. The hghest fishing intensity was registered at Chantuto and Panzacola. Fisheries technology is not the main problem for crocodilians, but rather activities such as high fishermen density, animals hunting, habitat lost and agricultural contamination. Crocodilians occasionally break nets trying to pull out fish or catch domestic animals but rarely attack humans. "

The American crocodile, Crocodylus acutus, inhabits a coastal, estuarine environment; its Atlantic distribution has included all the major islands of the West Indies, the Atlantic coastal lowlands from the southern coasts of Florida, and from Tamaulipas in Mexico to Venezuela (Campbell and Winterbotham, 1985; Schmidt and Ingor, 1957; Minton and Minton, 1973). The lemon shark, Negaprion brevirostris, frequents this same coastal, estuarine environment (Springer, 1938, 1940; Gruber, 1982).