García-Grajales, J. y A. Buenrostro-Silva. 2014. Abundancia y estructura poblacional de Crocodylus acutus (Reptilia:Crocodylidae) en la laguna Palmasola, Oaxaca, México. Revista de Biología Tropical 62(1): 165-172. (original) (raw)
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Revista de Biología Tropical, 2014
Population ecology of Crocodylus acutus (Reptilia: Crocodylidae) in Palmasola lagoon, Oaxaca, Mexico. Abundance and population structure are important parameters to evaluate and compare the conservation status of a population over time in a given area. This study describes the population abundance and structure of Crocodylus acutus in Palmasola lagoon, Oaxaca. The field works consisted of night surveys during the new moon phase, between the 21:00 and 24:00h. These were conducted during the dry and wet seasons and counted the number of individuals to obtain population estimates. Recorded encounter rates ranged from 32 to 109.3ind./ km in 40 journeys deployed with an average time of 18 minutes browsing. The estimated population size using the Messel´s model ranged from 32.7 to 93 individuals. For both seasons, there was a marked dominance of subadults, followed by juveniles and to a lesser extent adult individuals, as well as undetermined individuals (i.e. unknown body/size/length), in both seasons. There was also a significant association with mangrove areas (26.1%) by juveniles; the subadults´s individual use of superficial water (22.7%) and mangrove areas (15.7%); meanwhile the adults were observed on superficial water (9.7%). This information contributes to our understanding of the population ecology of C. acutus in the Palmasola lagoon where the estimated population size seems to show higher values when compared to other reports in the country.
ACTA ZOOLÓGICA MEXICANA (N.S.), 2007
Se estudió una población del cocodrilo de río (Crocodylus acutus) protegida por medio de la participación local en el estero La Ventanilla, Oaxaca, México, entre octubre del 2003 y mayo del 2004. Se estimó el tamaño, estructura y proporción de sexos de esta población para aportar información demográfica del cocodrilo de río mediante la aplicación de dos métodos de captura-recaptura. Se capturaron, midieron y marcaron 21 adultos (8 hembras, 13 machos), 11 subadultos (5 hembras, 6 machos), 88 juveniles (14 hembras, 62 machos) y 23 neonatos. La estimación del tamaño de la población mediante el modelo de Jolly-Seber resultó sesgada debido a que las pruebas de bondad de ajuste detectaron que las historias de captura no se ajustaron al supuesto de igual probabilidad de captura de este modelo. Las mismas historias de captura mostraron un ajuste significativo al modelo del estimador geométrico de frecuencia de capturas y las estimaciones de tamaño poblacional con este modelo fueron de 29.6 ...
Abundancia del cocodrilo americano (Crocodylus acutus) en la laguna Palmasola, Oaxaca, México
Revista de biologia tropical
Population ecology of Crocodylus acutus (Reptilia: Crocodylidae) in Palmasola lagoon, Oaxaca, Mexico. Abundance and population structure are important parameters to evaluate and compare the conservation status of a population over time in a given area. This study describes the population abundance and structure of Crocodylus acutus in Palmasola lagoon, Oaxaca. The field works consisted of night surveys during the new moon phase, between the 21:00 and 24:00h. These were conducted during the dry and wet seasons and counted the number of individuals to obtain population estimates. Recorded encounter rates ranged from 32 to 109.3ind./ km in 40 journeys deployed with an average time of 18 minutes browsing. The estimated population size using the Messel´s model ranged from 32.7 to 93 individuals. For both seasons, there was a marked dominance of subadults, followed by juveniles and to a lesser extent adult individuals, as well as undetermined individuals (i.e. unknown body/size/length), in both seasons. There was also a significant association with mangrove areas (26.1%) by juveniles; the subadults´s individual use of superficial water (22.7%) and mangrove areas (15.7%); meanwhile the adults were observed on superficial water (9.7%). This information contributes to our understanding of the population ecology of C. acutus in the Palmasola lagoon where the estimated population size seems to show higher values when compared to other reports in the country. Rev. Biol. Trop. 62 (1): 165-172. Epub 2014 March 01.
Revista de Biología …, 1996
Abstrae!: Spatial distribution and population size of Crocodylus acutus were estimated during December 1992-March 1993 in the Tempisque and Bebedero rivers, Guanacaste, Costa Rica. Along 47 km, 138 crocodiles were seen: 2.9 indlkm in Tempisque; 4.5 indlkm in Bebedero. The total length distribution in Tempisque (divided in areas B, C and D) presents individuals in Size 1 (hatchlings) in area B. Size II (recruits) were mainly found in area C, together with sizes III and VII (juveniles and adults). Area D lacked with sizes IV and VII. In Bebedero most were juveniles. Animals were noticed mainly for their "eyes": 48% to size 1, 36% to size IlI. Sexualy mature individuals were concen trated in areas C and D, and were 12.3% of the observed animals. The size distribution, without considering the "eyes" cIass, was 3% hatchlings, 24.2 recruits, 30.3% juveniles and 3% adults in Bebedero; and 13%, 12.3%, 14.5% and 12.3% respectively in Tempisque.
E. 2013. Aspectos ecológicos de la anidación de Crocodylus acutus (Reptilia: Crocodylidae) en dos localidades de la costa de Oaxaca, México. Acta Zoológica Mexicana (n. s.), 29(1): 164-177. RESUMEN. La anidación es uno de los periodos del ciclo reproductivo de los cocodrilos que tiene mayor impacto sobre la sobrevivencia de la especie, por lo que el objetivo del presente estudio fue describir los aspectos ecológicos de la anidación del cocodrilo americano (Crocodylus acutus) en la costa de Oaxaca, México. Se evaluaron nueve nidadas distribuidas en dos localidades (La Ventanilla n = 6; Palmasola n = 3). Los registros de campo incluyeron fechas de ovoposición y de eclosión, mediciones externas (distancia del centro del nido al árbol y a la orilla de agua más cercana, la cobertura dosel), e internas del nido (profundidad del tope del nido, profundidad y ancho de la cámara de incubación, humedad y pH del tope y de la cámara de incubación) así como característicasdelos huevos (número, fertilidad, largo, ancho y peso). Se realizó la prueba de Mann-Whitney a las variables internas y externas del nido y a las variables detamaño y fertilidadde las nidadas entre localidades. Se realizó un modelo lineal anidado a las medidas de ancho, largo y peso delos huevos. Las variables externas del nido no presentaron diferencias significativas entre localidades (p > 0.05).Para las características internas delos nidos se observó una sola diferenciasignificativa (p =0.04) a nivel del pH en el tope del nido (6.71vs 6.01), al igual quepara las variables ancho (4.60 vs 4.84 cm), largo (7.54 vs 7.66 cm) y peso (95.4 vs 104.4g) de los huevos. Este estudio brindalos primeros datos sobre la ecología de anidación del cocodrilo americano en Oaxaca y los resultados obtenidos sugieren un buen estado reproductivo en la región. Sin embargo, es necesaria la información de largo plazo para aumentar el tamaño de la muestra y confirmar el estado reproductivo de la especie. ABSTRACT.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 ofthe 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.
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.
Silva. 2011. Infestación y distribución corporal de sanguijuelas en el cocodrilo americano (Crocodylus acutus Cuvier 1807) (Reptilia: Crocodylidae) del estero La Ventanilla, Oaxaca, México. Acta Zoológica Mexicana (n. s.), 27 : 565-575. RESUMEN. Se estudió el grado de infestación y distribución corporal de sanguijuelas en el cocodrilo americano (Crocodylus acutus) de La Ventanilla, Oaxaca, México. El 32.9% (n = 26) de los organismos capturados portaban sanguijuelas. Se determinó que el género de sanguijuela que parasita a C. acutus en La Ventanilla es Placobdella. El 95.6% (n = 21) de los cocodrilos machos mostraron infestación baja y solo el 4.6% (n = 1) presentó infestación moderada, en el caso de las hembras el 100% (n = 4) presentaron infestación baja. El análisis de la distribución corporal mostró que la región donde se observaron concentradas el mayor número de sanguijuelas fue en la ingle derecha de ambos sexos. No se encontraron lesiones macroscópicas en las regiones corporales donde se encontraban dichos ectoparásitos, no obstante para descartar la posibilidad de que la infestación por sanguijuelas reduce la condición física de este reptil se sugiere el seguimiento de la población a través de estudios sanguíneos y coprológicos. Palabras clave: Sanguijuelas, distribución corporal, Crocodylus acutus, México.