Bat guano: record of climate change

Article By:

Wurster, Christopher School of Geography and Geosciences, University of St Andrews, Saint Andrews, United Kingdom.

Bird, Michael School of Earth and Environmental Sciences, James Cook University, Cairns, Australia.

McFarlane, Donald Department of Biology, Keck Science Center, The Claremont Colleges, Claremont, California.

Last reviewed:2010

DOI:https://doi.org/10.1036/1097-8542.YB100123

Bats are a ubiquitous group of flying mammals found on every continent except Antarctica, with highest abundance and diversity in the tropics and subtropics. Some species are very gregarious and may roost together in caves in substantial numbers. For example, the Mexican free-tailed bat may roost in maternity colonies reaching in excess of 20 million individuals in the semiarid parts of northern Mexico and the southwestern United States. These high population densities can result in bleached fur on the bats as a result of the high concentration of ammonia given off by microbial processing of bat urine and excrement (guano). Both big and smaller populations of bats produce considerable quantities of guano, which, over thousands of years, can lead to deposits many meters thick on the cave floor. Sizable guano deposits have been mined for fertilizer, with the remaining deposits now serving as valuable archives of past environmental change.

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