Adams, Rick A.
McGlaughlin, Mitchell E.
Franklin, Scott B.
Brown, Corina E.
College of Natural and Health Sciences; Biological Sciences: Program of Biological Education
University of Northern Colorado
Type of Resources
Place of Publication
University of Northern Colorado
Humans have an un-matched ability to alter the environment, which often has detrimental effects on other species, from tiny microbes to enormous plants and animals. Bats are the second-largest order (Chiroptera) of mammals with ca. 1,300 described species, many of which have declining populations due to human disturbances of ecosystems. Being the only mammals capable of flight, bats exploit numerous ecosystems and are known to roost in various habitats including caves, trees, mines, bridges, barns, etc. Although the roosting ecology of bats in ecosystems such as caves and forests has been well documented, no study has yet examined the relationship between bats and any cliff-face biodiversity to date. My dissertation focused on the impacts of rock-climbing on the activity of bats on Dinosaur Mountain on the City of Boulder Open Space and Mountain Parks. I quantified 1) the number of bat roosts, 2) the number of emerging bats, and 3) the species richness and biodiversity of roosting bats at nine different cliffs with variable levels of rock-climbing. I also used multivariate statistics (canonical correspondence analysis) to correlate climbing characteristics (e.g. use-level, number of routes, average route difficulty, seasonal closures, etc.) with measures of bat activity (e.g. bat species richness and the number of roosts, emerging bats, and foraging bats). I also examined the relationships among the presence of cliff- roosting bats on the biodiversity of organisms living in the soils of cliff crevices, as well as the biodiversity of mesofauna (e.g. small insects, spiders, mites, etc.). Specifically, I examined the biodiversity of bacteria and fungi using DNA analysis, and the biodiversity of mesofauna through visual microscopy. In addition, I used water quality assessment methods, which can be easily replicated in the field, to determine the influence of bats on the influx of nitrogen and phosphorus into cliff crevices, two elements that are essential for the establishment of microbes and flora in any ecosystem. By quantifying the frequency of rock climbing via time-lapse cameras, I found that cliff sites with zero rock climbing (compared to low and high rock climbing) had significantly greater bat richness (F2,105 = 7.25, p = 0.0011), biodiversity (F2,35 = 12.7, p < 0.0001), number of roosting bats (per m2) (F2,105 = 7.25, p = 0.0011), and number of foraging bats (per m2) (F2,105 = 8.67, p = 0.0003). However, the number of roosts (per m2) was significantly higher on cliffs with moderate levels of climbing (F2,105 = 4.98, p = 0.009). Through the DNA analysis, I found 400 species of bacteria and 269 species of fungi in the soils from the cliff crevices on Dinosaur Mountain. Overall, the biodiversity of bacteria was significantly higher in bat roosts compared to crevices without bats (t = 2.33, p = 0.012); although the biodiversity of fungi was slightly lower in crevices without bats, this difference was not significant (t = 1.62, p = 0.056). Bat guano contained significant levels of nitrate and phosphate, but no nitrite was detected. All three of these nutrients were higher in soils from/under bat roosts than in cliff crevices without bats (H2 > 7.82, p < 0.02), suggesting that the presence of bat guano and urine increases nitrate and phosphate levels. Moreover, the increased bacterial biodiversity in bat roosts likely facilitates the higher levels of nitrite (as well as nitrate) through higher levels of nitrification. Overall, rock-climbing appears to impact bats negatively, while bats seem to influence the biodiversity of soil bacteria and mesofauna positively, as well as increase the availability of usable nitrogen and phosphorus in cliff crevices, two nutrients that are essential for the development of all living organisms. The loss of bats on cliffs due to rock-climbing activities will likely have negative cascading effects on the biological communities of cliff faces, which are some of the most unique ecosystems on Earth.
Copyright is held by the author.
Available for download on Monday, June 01, 2020