Nesting ecology of the American crocodile in La Encrucijada Biosphere Reserve, Mexico

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

Potential distribution and habitat connectivity of Crotalus triseriatus in Central Mexico

The dusky rattlesnake, Crotalus triseriatus, used to be very abundant in many parts of the highlands of central Mexico, but with the increasing human population and associated activities, the rattlesnake habitats and populations have suffered drastic reductions and fragmentation. At the moment, the most important habitat features, associated with the presence of C. triseriatus, the current potential distribution and the landscape connectivity amongst the populations of the State of Mexico and Mexico City, are unknown. Therefore, we used the maximum entropy modelling software (MAXENT) to analyse the current potential distribution and most important habitat features, associated with the presence of the species. The variables with the highest contribution to the model were: proportion of Abies forest, minimum temperature of coldest month, maximum temperature of the warmest month, proportion of Pinus forest and annual precipitation. Furthermore, we found connectivity corridors only within mountain chains. Our results highlight the necessity for conserving the patches of Abies forest and preserving the populations of C. triseriatus and the connectivity of the landscape

Genetic variability and structure of an isolated population of Ambystoma altamirani, a mole salamander that lives in the mountains of one of the largest urban areas in the world

Amphibians are globally threatened by habitat loss and fragmentation; species within the order Ambystoma are not the exception, as there are 18 species of mole salamanders in México, of which 16 are endemic and all species are under some national or international status of protection. The mole salamander, Ambystoma altamirani is a microendemic species, which is distributed in central México, within the trans-Mexican volcanic belt, and is one of the most threatened species due to habitat destruction and the introduction of exotic species. Nine microsatellite markers were used to determine the genetic structure, genetic variability, effective population size, presence of bottlenecks and inbreeding coefficient of one population of A. altamirani to generate information which might help to protect and conserve this threatened species. We found two genetic subpopulations with significant level of genetic structure (FST = 0.005) and high levels of genetic variability (Ho = 0.883; He = 0.621); we also found a small population size (Ne = 8.8), the presence of historical (M = 0.486) and recent bottlenecks under IAM and TPM models, with a low, but significant coefficient of inbreeding (FIS = −0.451). This information will help us to raise conservation strategies of this microendemic mole salamander species

Diversidad de mamíferos de la Reserva Natural Sierra Nanchititla, México

La Reserva Natural Sierra Nanchititla (RNSN), por su extensión, es la segunda área natural protegida del Estado de México; sin embargo, se desconoce gran parte de su biodiversidad. El objetivo de este trabajo fue estimar su diversidad mastofaunística. Se utilizó el trampeo directo para la colecta de mamíferos pequeños y trampas-cámara para el estudio de los mamíferos medianos y grandes. Se calculó la diversidad a partir del índice de Margalef, y se evaluaron la dominancia y la equidad mediante los índices de Simpson y Shannon-Wiener, respectivamente. Se registraron 53 especies de mamíferos; 3 de ellas son el primer registro estatal, 10 son endémicas de México y 4 las considera en alguna categoría de vulnerabilidad el gobierno mexicano. En la zona habitan 5 de las 6 especies de felinos de México. La composición mastofaunística de la RNSN fue comparada con la de la sierra Purépecha, Michoacán, con la que comparte el 38% de las especies. De acuerdo con el índice de Jaccard, la similitud entre ambas es baja. Considerando los resultados, la importancia de la RNSN con respecto a su diversidad mastofaunística es evidente, así como la necesidad de delinear estrategias para su conservación

Ambystoma leorae (TAYLOR, 1943). New records, natural history notes and threat status

Ambystoma leorae (TAylOR, 1943), is endemic to the “Sierra Nevada” mountains of central México. its known distribution (Figs. 1A, 1B) is restricted to six locations within the protected area “iztaccihuatl Popocatepetl National Park” (iPNP). The salamander was originally described from the town of Rio Frio (TAylOR 1943); later it was recorded in three sites surrounding the area (vEgA-lóPEZ & AlvAREZ 1992; lE MOS-ESPiNAl et al. 1999), and in another two southern sites (lEMOS-ESPiNAl & AMAyA EliAS 1985; vEgA-lóPEZ & AlvAREZ 1992). These records are restricted to the upper tributaries of the Balsas River in the west of the iPNP, dispersed within an area of about 28 km x 0.65 km.Autonomous university of the State of Mexico (3530/2013MT

Potential distribution of Ursus americanus in Mexico and its persistence: Implications for conservation

The black bear Ursus americanus is an endangered species in Mexico. Its historical distribution has decreased by approximately 80% although its current distribution is not known with precision; it is only reported to be present in the mountains of Northern Mexico. This study proposes two ensemble models: Mexicoıs ´ black bear (a) potential distribution compared with Natural Protected Areas (NPAs); and, (b) persistence areas for 2024. The current distribution variables are coniferous forest, elevation and dry forest. Suitable habitat for black bear (354,047 km2 , 18.07% of the country) was found mainly in the north of the Sonoran biogeographical zone, along the Sierra Madre Occidental, the center and south of the Sierra Madre Oriental and some northern regions of the Altiplano Norte. Comparing these areas with NPAs documented that only 12.41% of potential distribution coincided with current suitable habitat. There are unprotected areas in Sierra Madre Occidental center and central and southern of Sierra Madre Oriental. The model for 2024 indicates a reduction of suitable habitat of 64.5%, mainly in the northern Sonoran zone and the center Sierra Madre Occidental. On the other hand, areas that will persist (125,673 km2) are located along the two main mountain ranges of Mexico. Identification of these sites will allow strengthening of long-term conservation strategie

Aspectos ecológicos de la anidación de Caiman crocodilus chiapasius (Bocourt, 1876) en la reserva de la biosfera La Encrucijada, México

Aspectos ecológicos de la anidación de Caiman crocodilus chiapasius (Bocourt, 1876) en la reserva de la biosfera La Encrucijada, México. — Existen pocos estudios sobre el caimán de anteojos, Caiman crocodilus chiapasius, realizados en México. En el presente estudio evaluamos las características clave de la ecología reproductiva del caimán en México. Se realizó una búsqueda de nidos entre abril y septiembre de 2014, y se observó que la construcción de los mismos tiene lugar en junio y las eclosiones, en septiembre y octubre. La fase lunar influye en la anidación. Asimismo, la altura del nido, la distancia al árbol más cercano y la distancia desde el borde superior del nido al primer huevo están relacionadas con el éxito de eclosión y la temperatura de incubación

Fototrampeo de mamíferos en la Sierra Nanchititla, México: abundancia relativa y patrón de actividad

La conservación de las especies y su manejo adecuado dependen de la disponibilidad de información sobre sus poblaciones, por ello es importante estudiar aspectos como la abundancia y el patrón de actividad. En esta investigación se utilizaron trampas-cámara para obtener índices de abundancia relativa y establecer el patrón de actividad de los mamíferos medianos y grandes de la Sierra Nanchititla, México. El trabajo se llevó a cabo durante el periodo de diciembre de 2003 a mayo de 2006, con un esfuerzo total de 4 305 días-trampa. Se obtuvieron 897 fotografías de 19 especies, las más abundantes fueron: Nasua narica, Sylvilagus floridanus y Urocyon cinereoargenteus, de acuerdo con el índice de abundancia relativa (IAR, número de registros independientes/100 días trampa), coincidiendo con estudios basados en métodos indirectos. El patrón de actividad de las especies registradas mostraron que el 67% son de hábitos nocturnos. Algunas especies mostraron diferencias con los patrones mencionados por otros autores, las cuales se relacionan principalmente con la estacionalidad, la disponibilidad de recursos y el sexo de los individuos

Uso tradicional de vertebrados silvestres en la sierra Nanchititla, México

Los pobladores nativos de México se han caracterizado por poseer conocimiento tradicional sobre las especies de flora y fauna de los ambientes donde habitan, así como por sus prácticas de aprovechamiento. En este estudio se documentó el uso tradicional de vertebrados silvestres por parte de los habitantes de las trece comunidades de mayor influencia de la Reserva Natural Sierra Nanchititla (RNSN), se examinó su disponibilidad como recurso en esta área protegida y se analizó la correlación entre ambas variables. Se aplicaron técnicas cuantitativas y cualitativas que muestran el grado de utilización del recurso considerando estimaciones poblacionales de las especies en la región y documentando el conocimiento de uso de los vertebrados por medio de entrevistas estructuradas. Se evaluó la abundancia relativa a través del conteo de excrementos y cámaras trampa del grupo con mayor frecuencia de uso (mamíferos) y se calcularon los índices de valor de uso por especie y familia de vertebrados. Todos los informantes (117) con excepción de uno aprovechan alguna de las 33 especies utilizadas en la región. Los usos mas frecuentes consisten en cubrir sus necesidades alimenticias y curativas. El grupo más utilizado es el de mamíferos, siendo el conejo (Sylvilagus floridanus) el más utilizado. Los habitantes locales usan con mayor frecuencia las diez especies con mayor abundancia en la región. Los resultados aportan información que contribuirá con las estrategias de conservación de recursos naturales en la RNSN

Morphologische anomalien bei anuren aus dem mittleren Mexiko: ein Fallbericht (anura: Ranidae, hylidae)

high rates of morphological abnormalities (malformations) in amphibians are attributed to parasites, chemical pollution, uv radiation and selective predation. the objectives of this study were to quantify and qualify the external, gross-morphological abnormalities in anurans of the sierra nanchititla natural Reserve (Mexico) and to identify possible causes. six specimens (6.23 %) out of 95 Lithobates forreri (BoulengeR, 1883), as well as two “bycatch“ specimens of Lithobates zweifeli (hIllIs, FRost & WeBB, 1984), and Hyla arenicolor CoPe, 1866, showed a total of eight types of morphological abnormalities. the observed abnormality rate thus slightly exceeded the assumed background rate of five percent in a population. among macroparasites, nematoda (Ozwaldocruzia sp. and Rhabdias savagei) and trematoda (Haematoloechus sp. and Gorgoderina tarascae) were present in internal organs, and chigger mites (Hannemania sp.) on the skin. In the muscle samples, lead (Pb) and copper (Cu) were not detected nor quantified, whereas low (physiological) concentrations of zinc (Zn) were found. In the water samples, Pb was not detected and Zn and Cu was within the level for rivers as accepted in Mexico. the authors reject as possible causes for the observed, increased rate of abnormalities: (1) the effect of macroparasites, due to the absence of trematoda of the genus Riberoia that are known to develop anatomical abnormalities; and, (2) chemical pollution by Pb, Cu and Zn. Possible causes are discussed