The relationships between urbanization, bat (Order:
Chiroptera) community structure, and bat foraging ecology with insect prey will
be investigated in Nanjing along an urban gradient. Many studies have examined
the use of urban areas by bats and have found that bats prefer wooded or
riparian areas within cities and avoid high density residential and commercial–industrial
areas (Sparks et al. 2005, Hourigan et al. 2006, Walters et al. 2007). Fewer
have examined the impact of urbanization on bat populations or community
composition. These studies found that bat communities in urban areas had lower
species richness than surrounding rural areas (Avila-Flores and Fenton 2005) or
are dominated by a few common species that have adapted well to urban
environments (Kurta and Teramino 1992, Sparks et al. 1998, Ulrey et al. 2005).
A discouraging indicator is the negative effect of urbanization on insect
abundance (McIntyre 2000, Kalcounis-Rueppell et al. 2007), the bat’s primary
food source. No study has documented or tested how bat communities have responded
to the fast transition from rural to urban in China.
The objective this study is to assess bat
community composition, movement, and foraging ecology along an urban-rural
gradient. We will capture bats in the
evening hours using two 12-m mist nets at 10 stream sites. Bats will be removed
from the nets, identified using a taxonomic key, weighed, measured, sexed, and
marked with a temporary dye on their dorsal fur. The bats will be held
individually in a single-use bag for a sufficient time period (about two hours)
for them to defecate so that guano can be collected. Time of capture will also
be recorded. Captures and recaptures
will be recorded to estimate population size using the Lincoln Peterson method
and movement from site to site. Abundance and species diversity will be
computed and compared between sites that are heavily urbanized, moderately
urbanized and not urbanized using a one-way ANOVA. While netting bats, a white
tarp will be set up with a spotlight shining on it for insect collection. The
insects will be collected using kill jars with approximately an inch of
alcohol. Insects will be brought back to the lab and pinned/pointed accordingly
to use for a reference collection in the guano analysis. The guano collected
from the captured bats will be preserved in vials of 70% alcohol solution and
analyzed separated by both species and site. Guano pellets will be examined
individually under a dissecting microscope using a micro-dissecting probe. A
ten-point grid will be used for qualitative analysis. The grid points will be
spaced 2.5 mm apart. Insect specimens on each point will be identified to
taxonomic Order and recorded using insect study guides and the reference
collection. Three samples will be taken for each species of bat, or site
captured if the species is caught in multiple locations. These procedures were
used successfully in a recent NSF-REU sponsored investigation of bat diet
composition in Alabama (Stone 2009). Prey selection between different bat
species will be compared using a Chi-Squared Test or two way ANOVA (using
species and site as main effects).The habitat, hydrological, land cover, and
biological data can be integrated into a geospatial databases to show spatial
patterns related to possible urbanization impacts.