Selección de sitios de anidación por el águila real Aquila chrysaetos (Linnaeus, 1758) (Accipitriformes: Accipitridae) en Janos, Chihuahua, México

Knowledge about the selection of nesting sites in birds of prey is essential to carry out any management of a population for its conservation. The golden eagle generally chooses rock walls to nest, and this selection is influenced by the natural and anthropic characteristics of the landscape. In Mexico, studying the golden eagle is important because it has a cultural value as a patriotic symbol and biological role regulating its prey populations. In addition, it is listed under the Official Mexican Norm 059-SEMARNAT-2010 in the category of threatened and there is little published scientific information on its ecology and biology in the country. Therefore, this study determined the habitat variables that influence the selection patterns of golden eagle nesting sites in Janos, Chihuahua; for which nesting sites and sites with similar characteristics without the presence of the golden eagle were located for its characterization. The obtained data was analyzed through generalized linear models, taking the presence and absence of nests as the response variable and the habitat characteristics of the sites as predictor variables. Fifteen nesting sites and sixteen sites without nests were located. Of 15 variables measured, there was only a statistically significant difference in the height of the rock walls (W = 44.5, p = 0.003001). The model with the best fit had an AICc value of 20.6, explaining 68% of the variability of the data and includes the variables of height of the rock walls and the roughness of the terrain, the latter being statistically significant (p = 0.0279). Terrain roughness was present in four of the top five candidate models reflecting the importance of topography for nest site selection that can provide isolation from disturbance for eagles.El conocimiento sobre la selección de sitios de anidación en aves rapaces es uno de los factores críticos para realizar cualquier manejo de una población para su conservación. El águila real generalmente elige paredes de roca para anidar, y esta selección está influenciada por las características naturales y antrópicas del paisaje. En México el estudio del águila real es importante debido a que tiene un valor cultural por ser un símbolo patrio y biológico por regular las poblaciones de sus presas, además, se encuentra listada en la Norma Oficial Mexicana 059-SEMARNAT-2010 en la categoría de amenazada y existe escasa información científica publicada sobre su ecología y biología en nuestro país. Por ello, se elaboró un estudio que determinó las variables de hábitat que influyen en los patrones de selección de sitios de anidación del águila real en Janos, Chihuahua. Se buscaron sitios de anidación de águila real y sitios semejantes sin presencia de la especie para tomar los datos de dichas variables; con esta información se analizaron los datos a través de modelos lineales generalizados, tomando como variable de respuesta la presencia y ausencia de nidos y las características del hábitat de los sitios como variables predictoras. Se localizaron 15 sitios de anidación y 16 sitios sin nidos; de 15 variables medidas solo existió diferencia estadística significativa en la altura de las paredes de roca (W = 44.5, p = 0.003001). El modelo con mejor ajuste tuvo un valor de AICc de 20.6, explicando el 68% de la variabilidad de los datos e incluye las variables de altura de las paredes de roca y la rugosidad del terreno, siendo esta última estadísticamente significativa (p =0.0279). La rugosidad del terreno y la altura de la pared de la roca que se presentaron en el mejor modelo reflejando la importancia de la topografía para la selección de sitios de anidación que puede proporcionar aislamiento de perturbaciones para las águilas

Vascular plants of the Médanos de Samalayuca natural protected area, Chihuahua, Mexico

Background: Inland sand dunes are expanding and increasing mobility. Knowledge on the plants growing on them is keystone for their management. One of the largest inland dune systems in Mexico is the Médanos de Samalayuca area. Questions: How many and which species of vascular plants are in Samalayuca? Which is the distribution pattern of that flora? Are there endemisms? Are there species of conservation concern? Studied species: Vascular plants. Study site and dates: Médanos de Samalayuca protected area, northern Chihuahua, Mexico; 2017-2022. Methods: A database was generated based on literature, electronic sources, herbarium specimens, photographing, and collection and identification of materials. Distribution, endemism level and conservation status were recorded. Results: The updated checklist of vascular plants for Samalayuca includes 400 species of 246 genera and 65 families. Most species grow in Mixed desert scrub and in Sand dune vegetation. Almost a half are restricted to the Megamexico 1 region, followed by the North American element. One species is Threatened according to the Mexican Official Norm NOM-059, while two are Vulnerable and one is Almost threatened according to the IUCN. Ribes fontinale appears to be extinct. Conclusions: Considering the arid, extreme climate and the low stability of the psammophilous vegetation, the flora of Samalayuca is richer than expected. The area is home to regional and local endemics. The data and information generated here is baseline for further management programs and action planning to protect these fragile ecosystems and the adjacent communities

Crotalus atrox (Western Diamond-backed Rattlesnake). Predation.

Se presentan eventos de depredación de crotálidos por un ave rapaz y otro por coyote en Areas Naturales Protegidas de México

Evaluation of pocket gopher diet in a perennial productive area

The desert pocket gopher (Geomys arenarius) is a fossorial herbivorous rodent of the family Geomyidae. Its distribution range is restricted to New Mexico and Texas, in the United States of America, and northern Chihuahua, in México. The Médanos de Samalayuca Flora and Fauna Protection Area (MSFFPA) is located in northern Chihuahua. Different economic activities are carried out in this region, mainly irrigated crops of pecans (Carya illinoinensis). Populations of G. arenarius have been recorded within these areas. Therefore, the objective of this work was to define the extent of the trophic niche and the changes in the physical condition of G. arenarius in a ranch within the MSFFPA over three contrasting seasons (dry, wet, and post-wet). Forty G. arenarius specimens were collected from Arantxa Ranch. Morphometric measurements and the weight of collected individuals were recorded, and the digestive tract was removed to prepare histological slides. Seven 25 m²-quadrants were established, and the species of the vegetation cover were recorded and collected for reference. The Seasonal Fitness Index (IK) and Levin’s Niche Breadth Index were calculated. Males had higher average measurements and weight than females. The IK was 2.82 ± 0.47 in males and 2.64 ± 0.61 in females. Significant differences in the IK between seasons were only found in females. The correlation between IK and plant cover was strong for males and females. The diet mainly comprised Physalis hederifolia, Dimorphocarpa wislizeni, and Cenchrus incertus. Levin’s index showed that G. arenarius is a specialist rodent. Sexual dimorphism was evident, with males larger than females. The physical condition index of gophers is influenced by resource availability. In other studies, this parameter has been related to changes in food availability. It has been reported that gophers tend to feed mainly on crops; however, pecan cultivation was not a major element in the diet of the desert pocket gopher, as it feeds on the vegetation associated with crops. Gophers are considered generalists; nonetheless, the present study showed that G. arenarius is a specialist, although this may be a consequence of anthropogenic activities

Fabáceas del Área de Protección de Flora y Fauna Médanos de Samalayuca, Chihuahua, México

El Área de Protección de Flora y Fauna Médanos de Samalayuca (APFFMS) con una superficie de 631.82 km² se localiza entre los municipios de Juárez, Ahumada y Guadalupe D.B., en el estado de Chihuahua, con cuenta con dos sistemas de sierras y un sistema complejo de dunas de arena de sílice. El clima es del tipo BWKx’ (e’) con una precipitación promedio anuales de 212 mm. La vegetación es dominada principalmente por Larrea tridentata y Prosopis glandulosa. Estudios florísticos en el estado de Chihuahua revelan que la familia Fabaceae es una de las más importantes en cuanto a diversidad, abundancia e importancia económica. Por ello, el objetivo del presente trabajo es actualizar la lista de Fabaceae del Programa de Manejo del APFF a partir de los ejemplares colectados del proyecto PJ018. Se establecieron cinco zonas de muestreo en la temporada seca, húmeda y post-húmeda (2017-2018) en búsqueda de leguminosas. Los resultados de este trabajo incrementan substancialmente el inventario previo de Fabaceae para el área dentro del Programa de Manejo del APFFMS al registrarse 27 taxa. El presente trabajo aumenta el conocimiento florístico y contribuye potencialmete a la toma de decisiones para su conservación y planeación