Bats

Executive Summary
Bats are the only group of mammals capable of true flight.  They make up over 20% of mammal species worldwide and are surpassed in numbers only by the rodents and mice.  There are 1,116 recognized species of bats, including 46 in the United States.  Sixteen species of bats have been documented in Missouri.  While some of these species are considered common and can be found in just about every one of Missouri’s 115 counties, others are considered rare, endangered, or even extirpated (Boyles, Timpone, & Robbins, 2009).  With Missouri’s abundant limestone, Missouri has been coined “The Cave Factory”, which in turn provides a lot of hibernacula for hibernating bats, as well as, an abundance of forested areas, which provide spring and summer habitat Missouri’s tree roosting bats.  As electric cooperatives operate across the landscape with new infrastructure, coops are sure to encounter regulations and conservation measures protecting threatened and endangered bat species found in Missouri.  These species include the Indiana bat (Myotis sodalis), Gray bat (Myotis grisescens), Northern long-eared bat (Myotis septentrionalis), and the Ozark big-eared bat (Plecotus townsendii ingens).  Below, is information on these listed bat species, along with measures to comply with regulations that protect these species related to utility impacts.

Threatened/Endangered Bats in Missouri and Northeast Oklahoma
Electric cooperatives in Missouri and Northeast Oklahoma can certainly encounter environmental concerns for the Indiana bat, Gray bat, Northern long-eared bat (NLEB), and Ozark big-eared bat (OBEB).  This can lead to a project requiring an incidental take permit under the Endangered Species Act (ESA), should appropriate surveys indicate that the project may “take” one of these listed species.  Understanding some of the biology for these species can be helpful in planning a cooperative project, so that line routing and project location can address conservation concerns for these species.  Addressing these concerns from the planning stage can decrease cost and streamline the timeline, compared to addressing the concerns on the back end of a project, which can potentially result in significant delays.

Indiana Bat
Indiana bats are federally and state endangered.  Listed in 1967, due to episodes of people disturbing hibernating bats in caves during the winter (USFWS, 2017).  The Indiana bat’s range is in all Missouri counties, impacting all of Missouri’s electric cooperatives, as well as those in northeast Oklahoma.  However, they are found in higher abundance in northern Missouri, because of the hibernaculum in Hannibal, Missouri.  Indiana bats begin entering caves and mines in October and November.  During hibernation, Indiana bats cluster in groups of up to tens of thousands of individuals.  These bats begin leaving hibernation sites in April and May to migrate to summering areas. For the hibernaculum in Hannibal, Missouri this results in Indiana bats dispersing across northern Missouri, southern Iowa, and west central Illinois, forming maternity colonies in forested areas (USFWS, 2017).  During summer, female Indiana bats roost under sloughing bark of dead or dying trees.  Roost tree are characteristically larger than most trees in the forest and are usually located on forest edges or open areas where sun exposure is high.  Indiana bats return to the same area, and often the same trees, year to year.  Most roosts are found in river bottoms and swamps, but large colonies in northeastern Missouri have been found in upland forests as well.  Females usually form maternity colonies of 60-80 adults, but few may have 150 individuals or even more (Boyles, Timpone, & Robbins, 2009)

Like most bats in Missouri, Indiana bats probably mate in the fall, but delay fertilization until spring.  During pregnancy, females select warm roosts, and give birth to one pup in June after a 60-day gestation period.  The young can fly at approximately 4 weeks of age.  Indiana bats preferentially forage over woodlands and surrounding fields while avoiding urban and suburban areas.  Females forage for most of the night returning 2-4 times per night to feed their young.  They feed on a variety of insects, with flies, beetles, and moths comprising most of the diet (Boyles, Timpone, & Robbins, 2009).

Figure 1:  Indiana bat (Myotis sodalis) on tree (USFWS midwest Credit Adam Mann)

 

Figure 2:  Indiana bat distribution (Boyles, J., Timpone, J., & Robbins, L. 2009).  The white counties do not preclude presence, it only indicates that there have been limited or no surveys in the area.  The Indiana bats range is considered throughout the entire state of Missouri.

 

Northern Long-eared Bat
Northern Long-eared bats (NLEB) are federally and state listed as threatened.  The NLEB is in all Missouri counties, impacting all Missouri electric cooperatives, as well as those in northeast Oklahoma.  The behavior of the NLEB is very similar to the Indiana bat.  NLEBs often hibernate in the same hibernacula with other species of bats and are occasionally observed clustered with or adjacent to other federally listed species, including Gray bats and Indiana Bats.  The NLEB was officially listed as threatened on April 2, 2015.  USFWS developed a final 4(d) rule on January 14, 2016.  Additionally, USFWS concluded that a critical habitat designation was not prudent on April 25, 2016.  This was based on the decision that designating critical habitat would increase the risk of vandalism and disturbance to bats at hibernation sites and could hasten the spread of white-nose syndrome.

White-nose syndrome (WNS) has been the primary instigation in listing the NLEB.  This disease affects hibernating bats and is named for the white fungus that appears on the muzzle and other parts of bats (USFWS, 2014).  No other threat is as severe and immediate as this disease.  If this disease had not emerged, it is unlikely the NLEB would be experiencing such a dramatic population decline.  Since symptoms were first observed in New York in 2006, WNS has spread rapidly from the Northeast to the Midwest and Southeast.  Numbers of NLEB have declined by up to 99 percent in the Northeast United States (USFWS, 2016).  Here in Missouri, the NLEB have undergone similar declines with > 90% population decline.  This interactive map by Whitenosesyndrome.org further illustrates the rapid spread of WNS.

Figure 3:  Northern Long-Eared Bat (Myotis septentrionalis) (Photo by New York Department of Environmental Conservation; Al Hicks

Figure 4:  Northern Long-Eared Bat distribution map (Boyles, J., Timpone, J., & Robbins, L. 2009).  The white counties do not preclude the NLEB from the county.  It only recognizes that there have been limited or no surveys in the area.  The NLEB range is the entire state of Missouri.

 

Figure 5:  Photo of White-nose Syndrome on bats.  Note the white muzzle. (New Hampshire Fish and Game Department, Al Hicks)

 

Gray Bat

The gray bat is the largest member of the genus Myotis in the eastern United States and is listed as both federally and state endangered.  This species is not found all across the state of Missouri, however the state does contain about 20 percent of the total population.  The gray bat has been listed as endangered since 1976 and their distribution in Missouri is primarily in the southern half of Missouri. 

Figure 6:  Distribution map of Gray bats in Missouri

At the time of listing, gray bats had declined by at least 50 percent rangewide and in Missouri populations had decreased by over 70 percent (Boyles, Timpone, & Robbins, 2009).  Gray bats are one of the few true “cave bats” in the eastern United States.  Unlike the Indiana bat and NLEB who form maternity colonies in trees, gray bat’s maternity, hibernation, bachelor and transient colonies are found almost exclusively in caves throughout the year.  Highly selective in their habitat choices, gray bats only use caves which provide the narrow temperature and humidity levels necessary to fulfill important life history requirements (Boyles, Timpone, & Robbins, 2009).  However, even though tree clearing does not directly kill gray bats, because they roost underground year-round, potential impacts can occur from tree clearing, especially in riparian areas.  We must ensure that connectivity remains between occupied caves/mines and foraging areas.

Gray bats use different roost in summer and winter and therefore migrate seasonally between their summer and winter caves.  Although migration distances of up to 325 miles have been reported in other parts of the range, gray bats in Missouri usually travel less than 125 miles.  These bats hibernate in very large colonies in relatively few caves, with 95 percent of the population using just 17 caves range-wide.  Gray bats forage over streams, rivers, and woodlands eating large numbers of beetles and caddisflies, but also occasionally eat moths, stoneflies, and flies as well.  During winter, both genders use the same caves.  Females enter hibernation in early October, while juveniles and adult males may remain active into November.  Gray bats return to the same hibernacula year after year, (Boyles, Timpone, & Robbins, 2009).  In the spring pregnant females congregate to form maternity colonies in summer caves.  A single pup is born in late May or early June, with young able to fly 20 to 25 days after birth.  While WNS can affect this species as well, often disturbance from human presence can lead to mortality, especially in late June and July, when flightless young are present, which can cause frightened females to drop their young in the panic to flee (USFWS, 1997).

 

Figure 7:  Gray bat (Myotis grisescens) Photo by Adam Mann, Environmental Solutions and Innovations

Ozark big-eared bat

The Ozark Big-eared Bat (OBEB) is now considered extirpated from Missouri.  Historically, this species was found in Stone and Barry counties in Missouri (Boyles, Timpone, & Robbins, 2009). The OBEB was federally listed as endangered on November 30, 1979 due to its small population size (around 100-200 bats), reduced and limited distribution, and vulnerability to human disturbance.  Currently, Oklahoma supports 1,600 -1,800 of the estimated 2,000 bats known to exist, with the balance of the population (about 200) in Arkansas (Center for Biological Diversity, n.d.)The OBEB inhabits caves year-round, similar to gray bats.  These caves are typically located in oak-hickory hardwood forests, where male and females hibernate together.  Hibernation clusters typically range from 2-135 individuals.  This species often return to the same maternity caves each year, during this maternity period males are solitary.  OBEB typically forage on the edge of forested habitat, feeding on moths, beetles, and other flying insects (USFWS, 2011).

Figure 8:  Ozark big-eared bat (Corynorhinus townsendii ingens) Richard Stark/USFWS

Figure 9:  Ozark Big-eared bat distribution (Boyles, J., Timpone, J., & Robbins, L. 2009)

 

REFERENCES

Boyles, J., Timpone, J., & Robbins, L. (2009). Bats of Missouri (Vol. 3). Indiana State University Center for North American Bat Research and Conservation.

Center for Biological Diversity. (n.d.). Ozark big-eared bat. Retrieved from http://www.biologicaldiversity.org/campaigns/esa_works/profile_pages/OzarkBigearedBat.html

G. (n.d.). Federally Threatened and Endangered Mammals and Plants of the Ozarks Aquifer. Retrieved December 05, 2017, from http://gulfcoast.harc.edu/WaterResources/KarstAquifers/OzarksAquifer/TESpeciesandCriticalHabitat/MammalsandPlants/tabid/2274/Default.html

U.S. Fish & Wildlife Service (USFWS).  (1997). Gray bat fact sheet.  Retrieved from http://www.fws.gov/midwest/endangered/mammals/grbat_fc.html

U.S. Fish & Wildlife Service. (2011, August). Ozark big-eared bat. Retrieved from https://www.fws.gov/southwest/es/Oklahoma/Documents/TE_Species/Species%20Profiles/Ozark%20Big%20Eared%20Bat.pdf

U.S. Fish & Wildlife Service. (2014, June). White Nose Syndrome: The devastating disease of hibernating bats in North America. Retrieved November 1, 2017, from https://www.whitenosesyndrome.org/sites/default/files/resource/white-nose_fact_sheet_6-2014_1.pdf

U.S. Fish and Wildlife Service. (2016, December 5). USFWS: Northern Long-Eared Bat Fact Sheet. Retrieved from https://www.fws.gov/midwest/endangered/mammals/nleb/nlebFactSheet.html

U.S. Fish and Wildlife Service. (2017, October 23). USFWS: Indiana Bat (Myotis sodalis). Retrieved from https://www.fws.gov/midwest/endangered/mammals/inba/index.html