The entrance of St. Clair Cave on the island of Jamaica is littered with bat wings. These appendages are, it seems, the least appetising part of the bat to the perpetrators of the carnage – feral cats.
Located north-west of Kingston in a rural region, the cave is what is known as a megaroost. It is home to an estimated two million bats belonging to ten species and is the only home of the critically endangered Jamaican greater funnel-eared bat (Natalus jamaicensis). There are only around 250 left.
Reports of cat predation at the site date back to the 1970s. The cats stake out the entrance of the cave at night and capture bats as they leave to forage in a seemingly endless stream that may last several hours.
Camera traps have captured the clever felines snagging bats out of the air and devouring their juicy bodies, leaving only the leathery wings behind. Pregnant females and juveniles are easy prey due to their more ponderous flight.
“Within a one metre by one metre exclusion plot, we found 20 pairs of wings in an hour,” says Jon Flanders, director of endangered species interventions at Bat Conservation International. “Half the time they're just doing it for fun.”
He and his colleagues have discovered that bats at the much smaller Stony Hill Cave in Portland, a residential area, are also vulnerable to cats. Stony Hill Cave is home to three species and is the only known roost of the critically endangered Jamaican flower bat (Phyllonycteris aphylla).
Cat predation was previously unknown at the site because no wings had been found. Camera traps showed why – as cats devoured bats and left their wings behind, non-native mongooses (Urva auropunctata) followed them and quickly scavenged the remains.
“In 28 nights, I watched 87 bats being eaten by cats,” Flanders recalls. Some of them were Jamaican flower bats – whose population consists of only a couple of thousand individuals at most.
“In 28 nights, I watched 87 bats being eaten by cats."
Damion Whyte, a biologist and PhD student at the Department of Life Sciences at the University of the West Indies Mona in Jamaica has also captured images of cats eating bats at the Green Grotto Caves (previously known as Runaway Bay Caves) on the north side of the island, near Discovery Bay, suggesting that cats may be a more widespread problem for cave dwelling bats on the island.
Jamaica is home to 21 species of bat and 15 of these species are dependent on around 17% of the island’s 950 documented caves. Five species are endemic to the island. Cave ecosystems are highly vulnerable to human disturbance, including the harvest of guano for fertiliser—and they can quickly collapse if disrupted. Even seemingly minor factors may in fact have huge impacts on bat ecology. Fewer than ten cats have been observed at each site—yet they take hundreds of bats each year.
Feral cats have been documented as bat predators in many regions of the world, with documented impacts in the United Kingdom, United States, Argentina, Australia, Spain and Italy, among other countries.
Flanders and his colleagues are working on installing predator exclusion fences at both St. Clair Cave and Stony Hill Cave. These structures feature an outward-facing lip that allows cats and other mammals to escape but prevents them from re-entering. They hope to have the fences in place by this fall, thus shielding some of Jamaica’s most vulnerable mammals from one of our most damaging commensal species.
Main image: feral cat with a bat in its mouth. Credit: Bat Conservation International
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