Revista Chilena de Historia Natural 82 (4): 523-542, 2009
RESEARCH ARTICLE
Structure and organization of rodent assembles of a forest of the Sierra Madre Occidental,
Durango, Mexico
Biodiversity of temperate forests in the mountain region called “Sierra Madre”, at western
Mexico, is rich. This zone lies in the Transition Zone, a biogeographical important area of North America characterized by a remarkable
local environmental heterogeneity. However, little is known about the taxonomic composition, and organization of the assemblage of
native small mammal, and the influence of local ecological factors, particularly from different vegetation types. Therefore, we were
interested in documenting the species composition and structure of the small mammal assemblages of this sierra and provide insights
into the nesting level of the community and deviations from a random organization. The study area was a place named “El
Durangueño” ranch, Durango, México. Three different vegetation types (grassland, and oak-pine and pine-oak forests) were sampled
there during every season of 2005 to 2006. During three consecutive nights rodents of each site were captured, recaptured, and
taxonomically identified. Results produced 520 individuals (386 captures, 134 recaptures) of 18 small mammal species (14 mice, four
squirrels) of different body sizes that represent neartic, neotropical, or shared affinity; endemicity of taxa was found as well as taxa in
some extinction risk category. Species richness and eveness were high and the diversity and population levels were moderate,
although high density of small mammals highlights oak-pine forest whereas dominance of some species occurs in pine-oak forest
perhaps due to disturbance. Spatial pattern of medium-size species was not at random. Assemble of species revealed a non- nested
pattern and displayed a log-normal distribution, characterized by four common and widely distributed rodent species
(Peromyscus truei, P. maniculatus, Reithrodontomys montanus, and Sigmodon leucotis), and
seven of restricted distribution. On the other hand, several species were allocated to different trophic-niche guilds, as revealed by their
reported food preferences, that were composed by up to two dominant species by site. In conclusion, the small mammal assemblage
of forests of Sierra Madre is distinctive and diverse, is not structured at random and vegetation may be one of the ecological factors
that have played an important evolutionary role.
Key words:
assemble,
conservation, rodent, Sierra Madre Occidental, temperate forest
