Given the current changes in climate, we expect to see changes in how bats interact with the environment," said Lauren Gallant, a researcher at the University of Ottawa and an author of the new study. "We inferred from our results that past climate has had an effect on the bats. Shifts in bat diet or species representation in response to climate can have reverberating effects on ecosystems and agricultural systems. Like sediment and ice core records, the guano core extracted from the Jamaican cave recorded the chemical signatures of human activities like nuclear testing and leaded gasoline combustion, which, along with radiocarbon dating, helped the researchers to correlate the history seen in the guano with other events in Earth's climate history.īats pollinate plants, suppress insects and spread seeds while foraging for food. "They really extended the toolkit that can be used on guano deposits around the world." "As a piece of work showing what you can do with poo, this study breaks new ground," said Michael Bird, a researcher in environmental change in the tropics at James Cook University in Queensland, Australia, who was not involved in the new study. These sterol markers pass though the digestive system into excrement and can be preserved for thousands of years. Plants make their own distinctive sterols. Cholesterol, for example, is a well-known sterol made by animals. The new study looked at biochemical markers of diet called sterols, a family of sturdy chemicals made by plant and animal cells that are part of the food bats and other animals eat. "It's a huge, continuous deposit, with radiocarbon dates going back 4,300 years in the oldest bottom layers." "Like we see worldwide in lake sediments, the guano deposit was recording history in clear layers. This is the first time scientists have interpreted past bat diets, to our knowledge," said Jules Blais, a limnologist at the University of Ottawa and an author of the new study in the Journal of Geophysical Research: Biogeosciences, AGU's journal for research on the interactions among biological, geological and chemical processes across Earth's ecosystems.īlais and his colleagues applied the same techniques used for lake sediments to a guano deposit found in Home Away from Home Cave, Jamaica, extracting a vertical "core" extending from the top of the pile to the oldest deposits at the bottom and taking it to the lab for biochemical analysis.Ībout 5,000 bats from five species currently use the cave as daytime shelter, according to the researchers. "We study natural archives and reconstruct natural histories, mostly from lake sediments. Analogous to records of the past found in layers of lake mud and Antarctic ice, the guano pile is roughly the height of a tall man (2 meters), largely undisturbed, and holds information about changes in climate and how the bats' food sources shifted over the millennia, according to a new study.
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