This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Flying foxes are the biggest bats in the world; they look like German shepherd puppies with 5-foot (1.5-meter) wingspans. But Madagascar's flying foxes are shrinking.
In a new study published in the Journal of Mammalogy, scientists showed that these giant fruit bats have been getting smaller over the past several decades, a change that the researchers suspect is related to an increase in large-scale commercial hunting. The paper's authors, both scientists at the Field Museum in Chicago, had noticed that the flying foxes represented by skulls and skins preserved in the museum's mammal collections seemed to be larger than the members of the same species they encountered while doing recent fieldwork in Madagascar. The researchers wondered why the modern bats were smaller than the older ones collected decades earlier.
"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," says Emily Cornelius Ruhs, a postdoctoral researcher in the Field Museum's Negaunee Integrative Research Center and the paper's lead author. But when Ruhs talked to her colleague Steve Goodman about it, he had a different hypothesis in mind.
Under Madagascar's national legislation, these fruit bats are considered vermin because they consume commercially important fruits. Flying foxes are classified as a game species and are currently hunted for food on a large scale in certain portions of the island nation. Goodman, the Field Museum's only full-time field biologist, has been living and working in Madagascar for nearly 40 years, and he noticed after looking at late 18th- and 19th-century museum specimens that "many of these animals were of monster size compared to animals we handle today.
Hence, the idea was formed that they have diminished in body size as a result of recent heavy hunting pressure and they are not living as long as they did in decades past. This underlines the importance of historical museum material in helping scientists to understand change through time," says Goodman. Goodman then visited the collections of nine natural history museums across the United States and Europe, where he examined 121 Madagascar flying fox specimens that were collected over the course of the past 150 years.
He took measurements of the bats' skulls and teeth, and then Ruhs performed statistical analyses of these data to look for overall trends in size. "We took all those measurements and put them together, and we looked at how they changed over time. We saw a clear drop in size starting around 1980, when we believe bat hunting became more commercialized," says Ruhs.
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