Mauricio Cotera

Charadrius montanus nests, mainly, in the desert grassland of western United States of America and spend the winter at the north of Mexico. The aim of this research was to monitor their populations in the El Tokio region, located at the northeast of the Mexican territory. A counting of all individuals was made during the summers and winters from 2003 a 2006 in eight sites, in the states of Coahuila, Nuevo León and San Luis Potosí, at least once during each season. The number and length of transects were determined from the size of the colony to be assessed. Density and population size were calculated for each sampling. The estimations were made with the Distance Beta 5.0 program Bird annual density was significantly different in the years of study (Kruskal-Wallis ANOVA, H = 41.13, P < 0.0001), and that of birds varied significantly among sites (F = 2.647; P = 0.0007). During winter, the density in the La Soledad, NL, was significantly higher (t 0.05, 3= 4.235, p = 0.024) than that recorded in the other localities; and in this time of the year it was greater than that estimated for summer, which reflects that the migratory populations mix with the residents. However, it is still unknown if the summer birds remain in the area during the cold time. The estimated winter population represents around 8 % of the total number of birds of the species, while that of fall adds 3 to 6 percent to it.

Se realizaron observaciones sobre los sucesos de temporada reproductiva de Spizella wortheni, se capturaron, midieron y marcaron ejemplares de la especie y se hicieron observaciones de individuos usando radiotelemetria. Se realizo una busqueda intensiva de nidos, se evaluo el microhabitat de cada nido encontrado y se hicieron observaciones de cuidado parental en un nido activo. Los resultados sugieren que el area de estudio cumple con las condiciones necesarias para sostener poblaciones reproductivas de la especie, sin embargo las practicas de pastoreo y uso de suelo en la zona pueden estar afectando el exito reproductivo del gorrion de Worthen

Summary Information deficit constrains our capacity to assess the status of threatened species in regional and global contexts. In this study of the endangered Worthen’s Sparrow Spizella wortheni, we first review its current and potential distribution using the species distribution software, Maxent. An initial basic model was constructed using historical records, and used to guide a subsequent search for additional populations in summer 2013. Using the information gathered from our survey, we built a second, breeding model, to update the current and potential species distribution. Population size was estimated using line transects of variable length to count singing males and calculate densities per 10 ha. We found 10 new small reproductive populations dispersed south of the established core area, increasing the extent of occurrence of the species from 25 km2 to almost 17,000 km2. Suitable habitat across the species’ range was more than threefold higher in the breeding compared with...

Mexico has a unique biodiversity that places it within the list of megadiverse countries; it has three of the 34 ecoregions of the world and sites that are considered wilderness areas worldwide. The use of Genomics as a tool for research in Mexico began in the late 1930s with work aimed at the genetic improvement of commercial crops and to understand the ecological foundations of the genetic variation in Drosohpila pseudooscura, however, it wasn’t until the decades of 1980-1990s that these tools were used for the study of natural populations of flora and fauna with purposes of conservation and management. Nonetheless, the potential that genomic tools have to improve the strategies and policies of management to ensure food production and conservation of wildlife in Mexico, these have not been widely applied. In this paper the areas of knowledge in wildlife where genomics have been applied in the study of natural populations of flora and fauna in Mexico were reviewed, and the practica...

Summary Information deficit constrains our capacity to assess the status of threatened species in regional and global contexts. In this study of the endangered Worthen’s Sparrow Spizella wortheni, we first review its current and potential distribution using the species distribution software, Maxent. An initial basic model was constructed using historical records, and used to guide a subsequent search for additional populations in summer 2013. Using the information gathered from our survey, we built a second, breeding model, to update the current and potential species distribution. Population size was estimated using line transects of variable length to count singing males and calculate densities per 10 ha. We found 10 new small reproductive populations dispersed south of the established core area, increasing the extent of occurrence of the species from 25 km2 to almost 17,000 km2. Suitable habitat across the species’ range was more than threefold higher in the breeding compared with...