Book Review: Conservation and Ecology of Pennsylvania’s Bats

Book Review: Conservation and Ecology of Pennsylvania’s Bats
By Merlin Tuttle

Cal Butchkoski removing a big brown bat from a mist net during a Pennsylvania workshop.

Conservation and Ecology of Pennsylvania’s Bats, edited by C.M. Butchkoski, D.M. Reeder, G.G. Turner, and H.P. Whidden. 2017, is a publication of the Pennsylvania Academy of Science. Twenty-eight contributors cover a wide variety of conservation-relevant topics. It summarizes the key ecological and economic roles of bats and traces the history of bat research and conservation efforts in Pennsylvania, which has one of America’s finest records of conserving bats.

A Wind Energy Voluntary Cooperation Agreement is reported to have gained beneficial results. However, the environmental review process does not cover most of the state’s species. And at least one of the state’s largest companies has refused to participate. The potentially serious, yet inadequately documented wind energy impacts on bats remain as unresolved threats.

This publication’s greatest strength is in providing the best documentation I’ve seen on the impact of White-nose Syndrome (WNS). It simultaneously tracks population changes based on hibernation and nursery roost counts and extensive netting and trapping in summer habitats, in addition to tracking the spread across North America. Alarming losses, often exceeding 90% are reported, comparing trends for formerly abundant, but highly vulnerable cave hibernators versus less affected and unaffected species.

The northern long-eared myotis (Myotis septentrionalis) is widespread across much of eastern North America but is poorly known. Though most appear not to hibernate in caves, many do enter caves in early spring. These bats appear to be among the most seriously harmed by WNS. On April 2, 2015 the species was federally listed as threatened by the U.S. Fish and Wildlife Service.

Populations of mildly affected big brown bats (Eptesicus fuscus) and unaffected red bats (Lasiurus borealis) appear to have grown, perhaps due to decreased competition from decimated species. Nevertheless, I was concerned to see an opposite trend for hoary bats (Lasiurus cinereus), the species most often killed by wind turbines. By 2013, capture rates for hoary bats had declined to just 83% of those seen prior to the arrival of WNS, despite apparently being unharmed by this new threat. This may be an early warning of unsustainable impacts of wind turbine kills.

The finding that many of the state’s cave hibernators appear forced to use sites where roost temperatures are insufficiently low or stable for ideal energy conservation may serve as partial explanation for extreme susceptibility to WNS. Most of America’s best hibernation sites, those with the widest ranges of stable temperatures (extra-large and multi-entranced), had been lost to bat use long before the arrival of WNS, since these are often the ones most heavily used by humans.

I agree that restoring and protecting such sites is likely the most important thing we can do to help rebuild populations. This was supported by evidence of surviving bats moving into roosts of lower temperature. I was also encouraged to see evidence of apparent recovery beginning among even the hardest hit species and concur that hibernation site disturbance must be kept to an absolute minimum during this period of hoped for population rebuilding.

Hoary bats (Lasiurus cinereus) are long-distance migrators, some traveling all the way from Canada to Mexico and back each fall and spring. Large, likely unsustainable, numbers are now being killed needlessly by careless production of wind energy.


Conservation and Ecology of Pennsylvania’s Bats is available through:



Speleobooks is an excellent source for virtually any book having to do with bats. This independent book and gift store has a long history of supporting bat conservation.