4,300 Years of Bat Poop Uncover Shifting Climate Conditions Over the Years [Study]

Over 4,300 years of bat poop may not be that significant to many, but for a group of scientists, it has offered insight into the diets of the bats and climate conditions that changed over the years.

The pile of bat poop, which is two meters tall, also called guano, presents history in distinct layers.

Researchers Find Notable Shifts in Bat Diets Over the Years

Scientists analyzed the poop located in the Home Away from Home cave in Jamaica, with its distinct layers in their past succession, and they discovered the shifts in the bat diets that have inhabited the cave for millennia.

(Photo: James Wainscoat on Unsplash )

In the study. "A 4,300‐year History of Dietary Changes in a Bat Roost Determined From a Tropical Guano Deposit," dietary shifts show traces of the kind of climate and environment over time, factoring in the variations in precipitation and temperature affecting the lives of animals and the existence of insects and plants that the bats devoured.

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Researchers focused on studying sterols, which are biochemical diet markers produced by plant and animal cells. These sterols traverse through the digestive system and could be preserved for thousands of years, as what was observed in this pile of guano.

They studied the poop of bats currently in the same area, which is home to about 5,000 bats from five different species. This provided the research team a baseline to place their findings against.

Spikes in Plant, Fruit Sterols

A spike in plant sterols was observed about a thousand years ago, which falls under the Medieval Warm Period (900-1,300 CE), during the time when the Americas were mostly dry.

Another spike was seen from around 1,350 BCE, an epoch known as the Minoan Warm Period. Dry conditions pose challenging conditions for insects, and at these times, bats were more interested in munching fruits.

"We inferred from our results that past climate had had an effect on the bats," co-author Lauren Gallant, a biologist from the University of Ottawa, was quoted in the study. "Given the current changes in climate, we expect to see changes in how bats interact with the environment. That could have consequences for ecosystems."

Chemical Signatures Indicate Human Activities Through the Years

An interesting finding was shifted in the carbon composition of the poop pile, which may have been due to the 15th century influx of sugarcane in Jamaica. Human activities such as nuclear testing and the use of leaded gas could also be detected with the chemical signatures in a pile.

Bats are essential to ecosystems since they control insect populations, disperse seeds, and pollinate flowers.

The cave study is a non-invasive, effective way to analyze the bats' diets and looking at their well-being over time that can reach over thousands of years using the right guano pile.

Similar study techniques could likewise be applied in other caves worldwide, the researchers note, and this could be very useful in areas with no lakes and underlying sediments that divulge the same information about the climate across history.