Registro de presencia y actividades de algunos mamíferos en el Desierto Chihuahuense, México

Abstract

Introduction: Photographic records are useful tools that had strengthen wildlife mammal studies as a noninvasive methodology providing a wide variety of information. The objective of this study is to document with images (automatic - trail cameras and manually – personal cameras) the species of mammals inhabiting the Mapimi Biospere Reserve (MBR), to highlight the morphologic characteristics that distinguish them, to record the area and vegetation type where each species was found and to determine some of their daily activities.Methods: Between 2009 and 2014, twelve field trips were made to Mapimi. In each trip we placed six trail cameras each at five locations (30 cameras total) for 24 h during six consecutive days, with 51,840 h photographic effort. Two sets of six cameras were placed in grassland habitat and three in shrubland habitat. Each camera was baited with 300 g of alfalfa mixed with sand in a tray placed 3 m from the camera. Between 2011 and 2014 two additional cameras were set to monitor a natural pond on the slope of a small mountain (San Ignacio) in the area with 5,760 h of photographic effort. In total we had 57,600 h of photographic effort. Images were also obtained from manual cameras of the authors while engaged in various research projects in the area with more than 2,000 photographs. These data for some species are directly from animals captured in the locality. Their main morphologic characteristics were highlighted, specific places, type of vegetation where each species was found and some of their daily activities.Results: A total number of five orders, 12 families, 27 genera and 31 species were recorded, representing 49 % of mammals known in the Reserve. With trail cameras 1,714 photos were taken and 15 species were recorded (Table 1). The species with highest number of records were Dipodomys nelsoni (n = 610), D. merriami(n = 469) and Netoma leucodon (n = 335). The ones with the lowest number of photos were Ictidomys mexicanus (n = 48) and Sylvilagus audubonii (n = 46, Figure 1).Trail cameras recorded five genera where the species level could not be determined: Myotis sp., Chaetodipus sp., Peromyscus sp., Ictidomys or Xerospemorphilus. With manual cameras more than 2,000 photos were taken and thirty species were photographed, only 16 were recorded with this method (Table 1). The collared peccary (Pecari tajacu) was the single species recorded only by trailed cameras.Discussion and Conclusions: Results obtained demonstrated that with trail cameras, morphological characteristics that distinguish most mammalian species can be observed clearly for most small, medium and large species. For some small species (such as Heteromyidae and Muridae) their features cannot be easily noted so their proper identity is difficult to determine. It is also important to discuss that only half of the known mammal diversity in the locality was recorded with trail cameras. Some small (such as Heteromyidae and Muridae rodents and bats), medium (as skunks) or large size species (as pumas) were not recorded with them, even though these cameras are generally considered a very effective method for mammalian inventories. As our results do not support this idea, we strongly recommend to combine direct trapping methods with trail cameras to get more complete and more realistic mammalian inventories.The highest numbers of records obtained with trail cameras were of Dipodomys nelsoni, D. merriami and Netoma leucodon, reflecting their numerical dominance in the ecosystem. Lower number of records of Sylvilagus audubonii, squirrels, deer, peccaries and other mammals are related with their low abundance and they occur only in very specific areas. The low numbers found of Lepus californicus were contradictory with previous studies, where they were much more frequently recorded. Skunks inhabit rocky and hills parts in the Reserve, and the presence of Spilogale gracilis was exceptional and as such represents a new record of this species for the Reserve. Documentation of mammalian species through photographic images contributes to different aspects of their biology that had not been addressed before in this location. Cameras allowed updating of information of some species and helped to identify knowledge gaps that can be addressed in the future to contribute to understand the dynamics of the mammal community in the Chihuahuan Desert.Key words: Manual cameras, new record, photographic identification, Spilogale gracilis, trail cameras.