Bats “are considered nature’s pesticides since they consume thousands of insects each night,” says public radio station KSMU at Missouri State University. But of the 16 bat species in Missouri, two are listed as endangered: the gray myotis and the Indiana myotis.
As part of KSMU’s Endangered Species Series, reporter Michele Skalicky notes that the gray myotis is doing relatively well today following sharp declines a few decades ago. Rick Clawson, resource scientist with the Missouri Department of Conservation, says gray myotis populations have been increasing for a number of years due to the protection of caves the bats use for hibernation and for rearing young.
BCI Founder Merlin Tuttle has been instrumental in focusing conservation attention on the gray myotis and has led efforts to gate and protect critical caves for more than 30 years.
The Indiana myotis, which lives under tree bark and in tree hollows during the summer and hibernates in caves in winter, isn’t faring quite as well. Missouri State University Biologist Lynn Robbins told KSMU that the Indiana myotis population has dropped some 50 percent nationwide during the past 25 years, while it is down more than 80 percent in Missouri.
He said Indiana myotis need very cold winter caves with constant cold temperatures, and “recent research, especially out of Bat Conservation International, is indicating that, as the caves warm up, the bats may be using more energy during the winter, which is either causing them to move to colder caves, or they just come out with not enough energy to complete their reproductive cycle.”
He said MSU scientist Dr. Tom Tomasi “has been working on metabolism of Indiana bats to see how the warmer cave temperatures might affect their energy budgets."
The radio station said that while things are rough for the species in Missouri, “the larger picture is rosier.”
The Indiana myotis ranges across much of the eastern United States and Robbins said that, over the last two or three decades, numbers have increased north and east of Missouri, while they declined in the southern part of its range.
Clawson told KSMU that he suspects warming weather in southern states may be involved in the decline there. “I can’t say definitively that this is the cause,” he said, but “since it's warmed up, … the population has shifted and now there are higher populations in caves in Indiana and New York and the northern Appalachians that were lower 25 years ago. Our caves in Missouri and Kentucky and other parts in the southern range, which were much higher in the late 1970s and early 1980s, those have declined.”
Clawson nonetheless says it’s important to protect the sites that the bats have occupied historically, “so that when conditions cycle back, … those roost sites would be available to them and they’ll be able to build back up here.”