Bat biologist Dr. Virgil Brack Jr., manually measures a large cluster of hibernating Indiana bats in Ray's Cave, Indiana. Ray's Cave held an estimated 77,687 bats during the biennial 2007 survey, making it the largest Indiana bat hibernaculum in the species' 16-state winter range.  USFWS photo by Andrew King.

A large hibernating cluster of Indiana bats (Myotis sodalis) within Ray's Cave, Indiana, with a superimposed 1 square-foot area and dots on bats' noses. USFWS photo by Andrew King.

A large cluster of I hibernating ndiana bats (Myotis sodalis) in Ray's Cave, Indiana. USFWS photo by Andrew King.

At the Service's request, bat biologists taking part in the 2009 biennial winter surveys of the federally endangered Indiana bat (Myotis sodalis) are currently gearing up to head underground with digital cameras in tow.  Digital photography is rapidly changing and improving how bat biologists have traditionally estimated winter bat populations within hibernacula (i.e., caves and mines).  Alas, anyone that has spent a few hours or days manually identifying and counting thousands of tiny bat noses on a computer screen can quickly attest, 'there has got to be a better way.'  A few bat counters have dared to dream of a day when photographs simply could be run through a software program and an accurate count of all the bats returned in an instant (± some acceptable amount of standardized error).  Fortunately, the weary bat counters' dreams may soon be closer to reality, thanks to some USDA Forest Service remote sensing specialists who recently accepted the challenge put before them. 

The Forest Service is used to taking on management challenges associated with the Indiana bat and its habitat.  The Indiana bat occurs on national forest lands in 14 states including Indiana's Hoosier National Forest.  The bat imaging project was proposed by Dale Weigel, a forester with the HNF, and Andy King, a biologist with the Service's Bloomington, Indiana Ecological Services Field Office; it was submitted as part of a national competition to the Forest Service's Remote Sensing Applications Center in Salt Lake City, Utah.  The RSAC selected the unique bat imaging project for funding and will soon begin feasibility testing using state-of-the-art image recognition software.  The Service's ultimate goal is to develop and implement a program that will more quickly, consistently and accurately identify and estimate the number of individual bats within digital photographs.  The Bloomington office will be providing the digital images for the feasibility tests. 

In recent years, the Service and its partners have been taking steps to improve the accuracy of Indiana bat population estimates and trends, which ultimately affect the Service's assessment of the bat's recovery criteria.  For example, in a 2006 Service-sponsored field test of bat surveyors, surveyors using digital photography had significantly less error in their population estimates than those using traditional survey techniques.  Digital photography is also valuable because it can reduce field survey time/disturbance levels and produce permanent records.  However, as a survey technique, digital photography is not without limitations.  For example, states with large winter populations of Indiana bats (e.g., Indiana, Kentucky, New York, Illinois, Missouri, and West Virginia) rarely have adequate staffing or funds to pay someone to spend weeks in front of a computer screen distinguishing pinkish noses from bent wrists and counting tens of thousands of identified bat noses in hundreds of digital photographs.  So, if the RSAC researchers are successful in testing and developing a standardized and automated system for estimating bat numbers from digital images, it will greatly benefit the Service and its partners in their Indiana bat recovery efforts. 

In addition to digital images of normal, healthy bat clusters, the Service and its partners will be providing RSAC researchers with digital images of hibernating clusters with varying amounts of fungal growth on their noses, ears, and forearms that is associated with the newly emerging threat, white-nose syndrome.  The current WNS outbreak apparently began at four hibernacula near Albany, New York, during the winter of 2006-2007 and rapidly spread this past winter to about 30 additional sites in New York, Vermont, Massachusetts, Connecticut, and perhaps Pennsylvania.  At least five bat species, including the Indiana bat, have been affected by WNS, and mortality rates have exceeded 90 percent at some sites. As initial funding allows, RSAC researchers will test the feasibility of imaging software to quickly scan and accurately detect individual bats exhibiting fungal growth.  Low levels of fungal growth, indicative of early onset of WNS, were not noticed at some affected sites until New York biologists later examined and discovered its presence in digitally enhanced photographs.  If feasible, digital imaging software would provide an efficient means of conducting standardized WNS surveillance at bat hibernacula across the eastern United States and Canada.

Points of contact for the bat imaging project are Andy King (Service/BFO, andrew_king@fws.gov), Dale Weigel (HNF, dweigel@fs.fed.us), and Dr. Randy Hamilton (RSAC, randyhamilton@fs.fed.us).

http://www.fws.gov/midwest/Endangered/mammals/inba/index.html

http://www.fws.gov/midwest/Endangered/mammals/inba/BatAilment.html

http://www.fs.fed.us/eng/rsac/