Adams, Rick A. (Rick Alan)
O'Shea, Thomas J.
University of Northern Colorado
Type of Resources
Place of Publication
University of Northern Colorado
As the world’s only flying mammals, bats fill an important ecological role in most ecosystems, acting as agents of seed dispersal, pollination, fertilization, and insect control. The human-mediated release of environmental contaminants has been implicated in the decline of many bat populations over the past few decades. Given bats’ ecological significance, I studied how bat presence and activity related to contaminated food and water sources in two global regions: 1) in and around the growing urban city of Chengdu, the capital of Sichuan Province, China, and 2) along the eastern slope of the Rocky Mountains in Colorado, U.S.A., which has been subject to 150 years of mining. In China (Chapter II), I tested mercury concentrations in fur and organochlorine concentrations in guano to assess their relationships to land use type and bat species, relative age, body condition, and phonic type. Because the Japanese pipistrelle (Pipistrellus abramus) had the highest fur mercury concentrations of bats sampled, in Chapter III I examined genetic identity and gene flow to confirm that all bats sampled were indeed P. abramus and to better understand local movements and potential implications of the contaminant concentrations. Finally, in Colorado (Chapter IV), I tested whether bat activity and feeding attempts differed locally above streams of high versus low metal contamination at high-elevation sites (>2,900 m). In China (Chapter II), total mercury concentrations were significantly higher in adult P. abramus than in adult Chinese noctules (Nyctalus plancyi) (P < 0.001), and significantly higher in adult N. plancyi relative to juveniles (P < 0.001). There was no significant difference in concentrations by land use type (urban versus suburban), but 57% of adult pipistrelles had fur mercury concentrations above the threshold for reduced homeostatic control, with the maximum (33 ppm) from an adult female in an agricultural area. There was no relationship between fur mercury concentration and bat body condition for either species. Hexachlorobenzene, alpha-chlordane, p,p’-DDE, o,p’-DDD, and p,p’-DDD were detected in guano but at levels well below those associated with harm. More bat phonic types were detected at a forested mountain site than agricultural or urban areas, though this could not be related to contaminant concentrations. In Chapter III, mitochondrial (cyt b) and nuclear studies confirmed that all individuals assumed to be P. abramus matched the species genetically and that there was weak population structure in Chengdu. This corroborated high gene flow in the area and a likely home range size of <10 km. Additionally, the P. abramus population had two mitochondrial clades, which may indicate ancient lineage separation due to glaciation and potential differences in susceptibility to physiological stresses. In Colorado (Chapter IV), there was no significant difference between the number of calls recorded at more contaminated sites and that at less contaminated sites. Though not statistically significant, the majority of feeding buzzes occurred above cleaner streams, suggesting that contamination could be an issue in habitats where fresh water is less available. Limited sample size and a short sampling period were constraints in all studies.
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Available for download on Thursday, May 23, 2019