On Madagascar, a furry creature with a puppy-like nose is a key player in pollination. The bat, called the Madagascan flying fox (Pteropus rufus), gulps down fruits, flowers, and nectar, resulting in dustings of pollen all over its face. With a wingspan of up to 5 feet, these bats travel as far as 30 miles during their foraging journeys, unwittingly spreading pollen far and wide. 

But a new study published in the Journal of Mammalogy shows that Madagascan flying foxes are physically shrinking over time. Biologists who had conducted fieldwork in Madagascar noticed that the flying foxes they observed appeared to be smaller than the ones housed in the mammal collections at the Field Museum in Chicago. 

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“I was thinking about a million different angles to explain why the bats were getting smaller. I wondered if it was related to changes in temperature or habitat,” said lead author Emily Cornelius Rohs, a postdoc at the Field Museum. 

Her coauthor Steven M. Goodman, however, had a different hypothesis: commercial hunting. These flying foxes are hunted for meat and are classified by the Malagasy government as a game species. Their population was tallied at about 300,000 in the early 2000s, but continued commercial exploitation has reduced it by about two-thirds.

To see whether the perceived change in body size correlated with the onset of large-scale hunting, Ruhs and Goodman reviewed the Madagascar flying fox collections at nine museums in the U.S. and Europe. They measured the skulls and teeth (the body parts most often preserved) of 121 specimens collected over roughly the last 150 years. Next, they compared pre-hunting and post-hunting sizes. 

The results showed a drop in size beginning in about 1980. “If you’re the biggest bat in the sky, you might be the easiest target. You’re also going to provide a hunter with the most meat,” explained Ruhs. 

While other factors could contribute to the trend—such as deforestation and climate change—hunting warrants targeted attention because flying fox meat provides a fair share of the protein for local diets, now showing up on roadside restaurant menus (“hotely”) and even supermarkets.

This, of course, is no good for the flying fox—both in terms of its size and its overall survival. And, since smaller bats constitute smaller ferries for pollen, it also shrinks the role of Madagascan flying foxes in pollination.

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Lead Image: Field Museum