Mammals
Robert M. Timm
Richard K. LaValCosta Rica is one of the most biotically diverse coun-
tries on earth, with 4% of known terrestrial plant and
animal species in only 0.04% of the world's land sur-
face. The country's mammal fauna is equally diverse,
with more than 207 species (4.8% of the world's 4629
species) in an area of 51,022 km^2. The majority of the
world's mammal species and Monteverde's fauna are
small (< 0.5 kg), nocturnal, and secretive. We know
considerably less about most neotropical mammals
and other vertebrates than we do about birds, which
are more easily observed and communicate with
sounds audible to humans. Although certain species
of mammals have been studied in Costa Rica (Janzen
1983a, Timm 1994, Vaughan and Rodriguez 1994),
and Monteverde is one of the best-known regions of
the country biologically, there has been little work on
the ecology, distribution, abundance, altitudinal zo-
nation, systematic relationships, and biogeography of
most mammals. Deforestation and other human dis-
turbances have had a significant impact on the native
mammals of the region; knowledge of Monteverde's
mammals is vital to understand how habitat changes
affect tropical montane mammals.
In this chapter, we provide an overview of the
mammal fauna of the Monteverde area. We discuss
the biology and abundance of some of the area's spe-
cies, document how these are changing, and explore
conservation issues. Most of the research on mammals
at Monteverde has centered on bats or rodents, the two
most diverse groups. Much of our knowledge of other
species consists of isolated observations. We augment
published reports with unpublished observations
made by ourselves and colleagues. We also examined
most of the Monteverde mammal specimens in mu-
seum collections to verify species identifications and
to understand better their systematics, ecology, and
distribution. We integrate this information into a list
of the mammals that occur in the region, document
their occurrence in each life zone, and estimate their
overall abundance (see Appendix 10).7.1. MethodsAlthough six major life zones are included in the
Monteverde region (Holdridge 1967; see Table 3.1 and7