This might be one of the most cataclysmic die-offs in recent history. It is happening now as we speak. Bats populations are plummeting. We are losing our hibernating bats in alarming numbers.
Just 6 years ago, in a cave in New York State, biologists discovered bats infected with a fungal disease previously unknown to this area. Because of the most obvious symptom, researchers dubbed it “White Nose Syndrome”. Since then, the population of Little Brown Bats has declined by 91%. Tri-colored bats by 90% and the already federally endangered Indiana bat population is down 70%. The worst hit is the Northern myotis, with 98% mortality. Big Brown bats have declined by – dare I say – only 41%, which is still alarming, but relatively speaking, the Big Brown is faring better than most.
Is this the point where you say, “Who cares – I don’t even like bats”? After all, they are Halloween scary, weird looking, and active at night when us humans are vision-handicapped. I don’t feel compelled to convince you that bats are likable, although I like them a lot. Whether humans approve of them or not, bats exist, and therefore must be an intrinsic member of the interrelated biota of earth.
Philosophical bent aside, bats are voracious consumers of mosquitoes and other flying insects. The 9 species of bats here in the eastern US are primarily insectivorous and can eat ½ to their full body weight in insects in a typical hunting night. In other parts of the world, bats are indispensable to the life cycle of plants by pollinating flowers and dispersing seeds. The economy of many tropical nations depends on them. If you eat bananas, avocados, breadfruit, peaches, dates, figs, mangoes, or guava, then you are beholding to bats. Saguaro cactus in the Southwestern US couldn’t do without their bat pollinators.
Happily, our migrating bats, Eastern red, Silver-haired and the Hoary, do not seem susceptible. The disease pathogen, Geomyces destructans, is a cold-loving rascal, thriving between temperatures of 41 and 57°F (5-14 °C). Hibernating bats are vulnerable because in order to save energy during the winter, their body temperature drops within this range. Plus, they hibernate in large colonies, passing white nose syndrome to one another like we would a common cold. Migrating bats don’t spend time in a hibernaculum with lowered body temperature and are therefore, not prone to infection.
Interestingly, G. destructans is found on European bats, but it is not fatal. Perhaps due to centuries of exposure there, bats have evolved a natural defense, which our bats don’t possess. Biologists theorize this new disease was brought over to the US on the clothes of a caver who inadvertently transported spores from a European cave to a cave in New York. The best hope for a remedy is that our bat populations too will develop immunity.
Keep in mind this is all very recent research. These findings come from the US Fish and Wildlife Service and New York’s Department of Environmental Conservation who are actively studying causes and ramifications. What is discovered next may alter what I’ve written here, or hopefully add to the limited knowledge base of this scourge on bats.
So, keep your eyes peeled toward the sky this spring. The migrants should be arriving back soon, and hopefully, our hibernators will emerge. Try to take note – are there as many bats as you’ve seen in years past? Are there as many mosquitoes as you’ve seen in years past? There just might be a correlation.
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