Search

Objetivo: Analizar la topografía de una isla del Golfo de California, México, mediante modelos digitales de elevación (DEM) de 30 m de resolución espacial para generar el primer modelo de distribución potencial para el carnívoro endémico Bassariscus astutus saxicola. Diseño/Metodología/Enfoque: Se empleó el software Maxent para modelar la distribución potencial del babisuri en la Isla Espíritu Santo. Los muestreos se realizaron en 2015-2016 en ocho bahías en el oeste de la isla en donde se capturaron n=74 individuos. Resultados: Las variables con mayores aportes a los modelos fueron elevación, (71.6%); índice de carga de calor (15%) y rugosidad del (11.8%). El modelo predijo (p<0.5) probabilidades de presencia del carnívoro en 3,018 hectáreas de la isla. SE obtuvo un valor alto de AUC (0.928), lo que indica que el modelo es exacto, y posteriormente se confirmó con un valor de pAUC=1.917. Limitaciones/Implicaciones del estudio: El hábitat del B. astutus saxicola era poco conocido principalmente porque es una especie endémica, y no existen publicaciones sobre su distribución dentro de la isla. Conclusiones: Este modelo muestra que las variables topográficas son útiles para explicar la distribución potencial del B. astutus saxicola, presumiblemente porque la topografía se relaciona con sitios que ofrecen refugio termal, alimento suficiente y cobertura de escape a depredadores, entre otras características del hábitat. [ABSTRACT FROM AUTHOR]

Remote piloted aircraft systems (RPAS) have become an important tool for the acquisition of geo-referenced information in agriculture. In particular, this technology can be used for land levelling, making agricultural field surveys more efficient and precise. Due to the above, and the need for high resolution cartography, an evaluation of a prototype of RPAS for topographical surveys, based on georeferenced RGB images, including ground control points, was carried out. To this end, an autonomous flight mission was carried out at the experimental field of the Chapingo Autonomous University, Mexico, at an altitude of 20m, with a horizontal speed of 1m/s and winds of no more than 5 km/h, covering an area of 2151 m² (0.23 ha). The RGB images obtained with the RPAS were corrected by means of ground control points and the dense cloud of points generated was compared with a post-processing GPS topographic survey, obtaining absolute and standard errors of 0.020 and 0.024 m, respectively. [ABSTRACT FROM AUTHOR]

This study evaluates the influence of the road type and infrastructure (culverts) on the numbers of vertebrates killed on the Xalapa - Puebla highway (section: Banderilla - Amozoc) in the central mountainous zone of the state of Veracruz. The study was carried out on three different road types (varying according to the number of lanes and type of structure that separates the lanes) along which sites were selected where there was a culvert considered as a potential wildlife crossing. Roadkills at each site were counted and related to the presence - absence of culverts, the slope of the right of way with respect to the road, as well as the road type. A greater number of roadkills occurred in the two-lanes highway followed by the highway divided by central vegetation barrier and the highway with central barrier of concrete wall. In none of the types of road studied were found an effect of the presence of culverts on the number of vertebrates killed. In addition, a negative relationship was found between the number of roadkills and the slope of the right of way. This study helps to understand the factors that limit the crossing of vertebrates on the roads and discusses the implications of road infrastructure planning - construction for wildlife. [ABSTRACT FROM AUTHOR]