OCTOBER 1989 - City of Boulder

ats and extirpated species from the calculations, 27% of the
potential mammalian fauna was observed or captured during the
study period. Notice (Tab1 e 2) that on1 y one species (Peromvscus
maniculatus) was found in more than two habitats, five species
were found in just two of the habitats, and four species were
found in a single habitat. This reflects a pattern observed in
the distribution of mammals in Colorado. Fwty-nine percent of
the fauna (53 species) occur in only one or two habitat types,
eighty-eight species occur in five or fewer habitat types
(Armstrong 1972). The numbers of individuals captured during this
study appear- t o be low compared to other studies completed in the
county (Armstrong and freeman 1982, Armstrong and Freeman 1984).
In 1850 trap nights Armstrong and Freeman (1982) captured eight
species, and 214 individuals. Due to the annual and multiannual
cycling of some rodent populations, and the fact that all of the
mentioned studies were accomplished at different times of the
year it is not possible to make comparisons among studies.
Traditional ly population numbers appear to be low during the
spring and early summer months and increase during the fall
(Sad1 ei r 1965). However, Brown (1980) found populations of
deermice in the Rocky Flats area that did not follow reported
seasonal or annual patterns, but di d find popul at i ons of Western
Harvest Mice that showed seasonal variation with the highest
densities occurring in the fall.
The faunal relationships of species captured are indicated in
Table 2. Note that the Eastern, Chihuahuan, and Campestrian