Myotis Habitat Protection and Enhancement for Endangered Indiana bat, Gray bat, and

Northern long-eared bat.

Blake Ellett

April 27, 2015

I. Introduction

The Indiana bat (Myotis sodalis), Northern long-eared bat (Myotis septentrionalis), and gray bat

(Myotis grisescens) are all Myotis species of bats that are listed as threatened or endangered

throughout their range in the United States. These bat species provide several ecosystem services

including insect control through predation (Mamm, 1981). These species have a broad

geographic range, stretching from Canada, Florida, and Missouri. There are two classes of bats,

cave dwelling bats, which inhabit caves all of the year or only in the winter hibernation months,

and tree dwelling bats, which reside specifically in forested habitats (Trani, M). The species

addressed in this report pertain to the cave dwelling Myotis species. These species have been

influenced by anthropogenic practices such as habitat clearing and urbanization along with

species declines associated with White Nose Syndrome (WNS), caused by the fungus Geomyces

destructans, which was introduced into the United States at Howes Cave, New York in 2006

(georgiawildlife.com/WNS, Gargas et. Al. 2009). The spread of WNS has decimated populations

of Indiana bats, Northern long-eared bats, gray bats, and several other indigenous species across

the U.S. With habitat loss increasing, and confronted with the new realities of high mortality

rates stemming from WNS, it is increasingly important to protect and enhance habitats for these

species as we are seeing drastic declines in population numbers (Photo 4, Appendix A). In the

following sections, discussion will include species description and life histories, discussion of

issues relating to the threatening and endangerment of the selected Myotis species, and policy

suggestions for recovering the indigenous populations.

II. Species Descriptions

Indiana bat

Indiana bat formally attained endangered species status through the USFWS (United States Fish

and Wildlife Service) on March 11, 1967 (Photo 1, Appendix A). Its distribution includes most

of the eastern United States from Oklahoma to Wisconsin, east to Vermont, and south to

northern Florida (Barbour and Davis 1969).

Indiana bats are best identified by a distinctively keeled calcar, toe hairs that do not extend past

the toe nails, a pinkish nose, and blunt tragus (georgiawildlife.com). The fur is short, grayish,

and typically duller than other Myotis species. Dorsal fur is darker at the base than the tip.

Forearm length is 35 to 41 millimeters, and weight ranges from 5 to 10 grams. While in flight,

the wing span is approximately 9 to 11 inches (fws.gov).

Indiana bats use caves and abandoned mine portals as hibernacula. During winter, they have

very specific hibernation requirements and occupy areas that maintain a consistent temperature

range (39-46 degrees F) and humidity range (>74%) (georgiawildlife.com). As such, very few

caves provide adequate microclimate for these bats (USFWS 2007). After hibernation, females

leave the hibernacula and fly to nursery sites to raise their young. Although some males may

leave with the females, others stay in or near the hibernacula throughout the summer months

(Barbour and Davis 1969).

At their summer roosts, Indiana bats typically live under the exfoliating bark of trees and in dead

snags of trees (Kurta and Kennedy 2002). It has been recognized that floodplain forests were the

significant habitat for Indiana bat utilization for foraging (Humphrey et al. 1977), but recent

studies indicate that this species also uses upland habitats (Sewell et al. 2006). Most known

maternity roosts have been located in or near wooded areas where some light gap is present

allowing full or partial solar exposure to the roost site. Maternity colonies typically roost under

the exfoliating bark of dead or live trees, and utilize dead snags as roosting sites (Gardner et al.

1991).

Indiana bats leave their maternity grounds mid-August to September and migrate toward their

hibernacula where they swarm near cave openings until they enter hibernation (Barbour and

Davis 1969). During the fall, mating occurs and females store sperm through their hibernation

until they inseminate themselves in the spring prior to spring migration (Barbour and Davis

1969).

Gray bat

The gray bat (Photo 2, Appendix A) is a medium-sized bat with a forearm length of 40 to 46

millimeters (1.6 to 1.8 in.) and a wingspan of 275 to 300 millimeters while in flight (10.8 to 11.8

in.) (Barbour and Davis 1969). The weight of the gray bat ranges from 7 to 16 grams it usually

falls between 8 and 10 grams (0.28 to 0.35 oz.) during the summer but may increase to 16 grams

(0.56 oz.) just before migration (georgiawildlife.com). The wing membrane is attached to the

foot at the ankle, this is one of the distinguishing traits for this species (Gore 1992). The fur is

gray immediately following the molt in midsummer but may bleach to chestnut-brown or bright

russet by the following May or June, especially in reproductive females (fws.gov).

The gray bat occurs over a limited geographic range in limestone karst areas of the southeastern

United States, as this species is primarily a cave dwelling species (Tuttle 1976). The majority of

known gray bat populations occur in Alabama, Northern Arkansas, Kentucky, Missouri, and

Tennessee (Brady et al. 1982), with small maternity populations as far north as southern Indiana

(Barbour and Davis 1969), and as far west as southeastern Kansas (Brady et al. 1982). The

species was listed under the ESA in 1976 as endangered throughout its range.

Gray bats are true “cave bats” and typically use caves as both winter and summer roosts. Less

than 5% of known caves systems provide suitable habitat for gray bats across its range (Mitchell

and Martin 2002). During the summer maternity season, gray bats typically roost in relatively

warm caves with temperatures ranging from 13.9° to 26.3°C (57° to 79°F). During the summer

maternity season, gray bats roost in caves within 2.5 mi of a stream or reservoir which are then

used as foraging corridors (Brady et al. 1982).

As riparian specialists, gray bats frequent streams, lakes, and wetlands during foraging and

distribute themselves 17 km upstream and downstream of their roost cave (LaVal et al. 1977).

The species will often travel great distances during nightly movements to and from roosts and

foraging areas and have been found to move up to 48 kilometers from their roost cave (Brady et

al. 1982). Gray bats have been shown to preferentially feed on aquatic insects such as

Trichoptera, Plecoptera, Ephemeroptera, and Diptera (Brady et al. 1982).

Northern long-eared bat

Northern long-eared bats can be distinguished from other Myotis species in their range by their

long ears (extended past their nose when pressed down over their face) and longer more pointed

tragus (Photo 3, Appendix A). The Northern long-eared bat’s forearm lengths range from 32 to

39 millimeters (Barbour and Davis 1969). The Northern long-eared bat has been historically

considered to be a common bat within forests throughout most of its range. However, with the

introduction of WNS and the subsequent population decline, as well as habitat loss and

degradation, this is no longer true as this species is now listed under the ESA as threatened

(USFWS, 2015). The southern extent of the range of the Northern long-eared bat begins in

northern Georgia and Alabama and expands north into southern British Columbia, Canada

(fws.gov).

Northern long-eared bats spend the summer months in forested habitats and forage through

riparian corridors. Maternity colonies of this species usually occur under exfoliating bark of

trees (Lacki and Schwierjohann 2001), although roosting use of bat boxes and human made

structures like shutters and bridge decks has been documented (Broders et al. 2004). During the

winter months, from late October through April, Northern long-eared bats can be found

hibernating in caves and abandoned mines (Krynak, 2010).

As with other Myotis in their range, Northern long-eared bats breed in the fall during swarming,

prior to hibernation. Females store sperm over hibernation and eggs are fertilized in the spring

shortly after awakening from hibernation. Pups are born in spring and become volant in under a

month. In late summer, maternity colonies begin to break up and both sexes begin to move to

swarming and hibernation sites.

III. Issues Related to Threatening/Endangerment of Myotis species

These Myotis species face a number of anthropogenic and biological issues related to the success

of the species moving forward. Due the nature of these species being cave dwellers through their

wintering ranges and requiring specific conditions within these caves for survival, they only have

a few suitable cave systems for roosting habitation within their range. Protecting these important

ecosystems from human disturbance is extremely important due to the sensitivity of these species

during hibernation and how easily they can become awakened/aroused during their hibernation

which causes them to use up vital energy (fws.gov).

WNS creates a biological disturbance to the bats through a fungal growth on the wings and face

during hibernation. WNS is decimating populations of cave dwelling bats across North America

(Blehert 2009). It is hypothesized that WNS affects bats while hibernating by arousing the

infected individual more frequently and for longer amounts of time as opposed to an un-exposed

individual, burning through fat reserves stored for the winter hibernation (USFWS 2011). WNS

also affects the wing membrane, creating scarring and physical holes within the membrane.

Direct degradation of wing membrane can decrease physiological functionality and cause issues

such as reduced thermoregulation, dehydration, and physical scarring affecting the physical

mechanisms of flight (USFWS 2011).

Direct habitat loss and degradation also affect bat species throughout North America. Through

urbanization projects, roadway construction/expansion, and development, large amounts of

forested habitat, exhibiting summer roosting habitat, are removed or degraded. Along with the

physical removal of summer roosting trees, decreased water quality can affect these species by

not allowing riparian insect species to reproduce due to issues with water quality and habitat

availability. Indiana bat, gray bat, and Northern long-eared bat use riparian and stream corridors

to feed in aquatic-based habitats where specific types of insect prey are abundant (Brack 2006).

Protecting these important forested areas are key in providing suitable habitat for summer

ranging Myotis species.

IV. Policy Suggestions

In this section, policy suggestions are discussed for protecting and enhancing Indiana bat, gray

bat, and Northern long-eared bat habitats and hibernacula across their known ranges. Suggestions

for protecting and enhancing these habitats include public education, mitigation of snags for

potential roosting sites, increases habitat protection, and monitoring of species populations

throughout the ranges.

Public education is an important component of raising awareness and support for protecting vital

ecosystems and individuals of Indiana bat, gray bat, and Northern long-eared bat. Providing

interactive discussions between conservation professionals and the general public can provide a

personal experience that can better educate and inform private landowners and citizens.

Providing interpretive signs at utilized hibernacula caves can inform the general public of issues

related to WNS and impacts related to disturbance. Along with interaction and proper sign

utilization, continuing to provide useful literature and scientific documentation can further build

support of the science behind these threatening issues and build a factual base of evidence to

support conservation efforts.

Mitigating snags for potential roosting sites of Myotis species can be implemented on various

projects, including Department of Transportation projects (DOT). Mitigation banking is already

a lucrative and important component of stream and wetland protection and enhancement across

the U.S (mitigationbanking.org). Many states require direct mitigation purchases of credits when

jurisdiction waters or wetlands are impacted in any way through construction, maintenance, and

development projects. These mitigation banks all have different values of credits that can be

purchased, depending on the quality of the watershed, location in regards to tidal influenced

waters of the U.S., and wetland system extent within the project corridors closest bank. This

policy was put in place to enact a no net loss policy to wetlands and jurisdictional waterways in

the United States and to protect our vital biological systems. Myotis bat species roost in dead

snags and under sloughing bark. Mitigation of dead snag removal in DOT projects could ensure

that endangered and threatened Myotis species are provided ample summer roosting habitat. This

creates an entire new part of mitigation and encourages individuals to protect snags for Myotis

utilization by providing a monetary incentive. Ecological surveys can estimate the quality of the

habitat and quantity of suitable roost sites to be mitigated at a certain ratio (i.e. 1:1) depending on

quality.

Direct protection of suitable habitat for Myotis species can increase the amount of suitable

roosting and hibernacula sites across the species range. Forested habitats are becoming

increasingly fragmented, isolated, and degraded. Protecting these forested areas is integral in

providing the suitable summer roosts and foraging habitats for bat species. Myotis species utilize

upland and riparian habitats for foraging. Riparian corridors can be protected through buffer

zones adjacent to streams. Buffer zones vary in width, ranging from 10 ft. to 300 ft., depending

on the required service of the buffer (Hawes and Smith 2015). Cave hibernacula can be protected

through the installation of gates and restrictive devices that limit the access to those who receive

written permission from a designated protection agency, i.e. the USFWS.

Monitoring Myotis species is important for quantifying survival rates, range distributions, and

overall health of the species. Winter caves surveys for WNS should be conducted at all known

infected sites, counting affected and dead individuals for year to year correlations of survival

rates within the hibernacula. Along with cave surveys, summer mist netting surveys should be

conducted to identify, evaluate, and count bat species across known ranges. These surveys are

conducted by USFWS endangered species permit holders. Mist nets are erected in foraging and

flyway corridors, physically netting bats as they emerge for nocturnal foraging. These mist

netting surveys can provide useful information on diversity and known ranges for specific

species.

We have just begun to understand the ecological significance of bats in North America. Indiana

bats, gray bats, and northern long-eared bats face a multitude of issues related to survival. WNS

and habitat degradation are the leading causes of mortality for Myotis species. Through careful

policy implementation and protection, we can provide avenues in which to increase the quality of

habitats, forested and cavernous, for threatened and endangered Myotis species in North

America.

PHOTOGRAPHIC LOG

Photo: 1

Description:

Indiana bat (Myotis

sodalis)

Source:

http://ecos.fws.gov/

speciesProfile

Photo: 2

Description:

Gray bat (Myotis

grisescens)

Source:

http://ecos.fws.gov/

speciesProfile

Photo: 3

Description:

Northern long-eared

bat (Myotis

septentrionalis)

exhibiting WNS

Source:

http://www.fws.gov/

midwest/

endangered/

mammals/nlba

Photo: 4

Description:

White nose positive

bats

Source:

http://www.in.gov/

dnr/fishwild/5404.htm

Appendix A. Photographic Log

Appendix B. Citation

Blehert, David S et al. "Bat white-nose syndrome: an emerging fungal pathogen?" Science 323.5911 (2009): 227-227.

Brack, Virgil. (2006) Diet of the Gray Myotis (Myotis grisescens)., “Variability and consistency, opportunism, and selectivity.” Department of Ecology and Organismal Biology, Indiana State University, Terre Haute, IN 47089, USA (VB) Apartado 24-5655, Monteverde, Puntarenas, Costa Rica (RKL)

Barbour, R. W. and W. H. Davis. 1969. Bats of America. The University Press of Kentucky, Lexington, Kentucky, 286p.

Broders, H. G. and G. J. Forbes. 2004. Interspecific and Intersexual Variation in Roost-site Selection of Northern Long-eared and Little Brown Bats in the Greater Fundy National Park Ecosystem. Journal of Wildlife Management 68(3):602-610.

Brady, J.T., T.H. Kunz, M.D. Tuttle, and D.E. Wilson. 1982. Gray bat recovery plan. U.S. Fish and Wildlife Service, Denver, CO

Gardner, James E, James D Garner, and Joyce E Hofmann. "Summer roost selection and roosting behavior of Myotis sodalis (Indiana bat) in Illinois." (1991).

Gargas, Andrea et. al. "Geomyces destructans sp. nov. associated with bat white-nose syndrome." Mycotaxon 108.1 (2009): 147-154.Lorch, Jeffrey M et al.

Gore, J. A. 1992. Gray bat. Pages 63-70 In S. R. Humphrey (ed.). Rare and endangered biota of Florida. University Presses of Florida, Gainesville.

Hawes, Ellen and Smith, Markelle. “Riparian Buffer Zones: Functions and Recommend Widths.” 2015. Yale School of Forestry and Environmental Studies.

Humphrey, Stephen R, Andreas R Richter, and James B Cope. "Summer habitat and ecology of the endangered Indiana bat, Myotis sodalis." Journal of Mammalogy (1977): 334-346.

Krynak, Timothy J., "Bat Habitat Use and Roost Tree Selection for Northern Long-eared Myotis (Myotis septentrionalis) in North Central Ohio" (2010). Masters Theses. Paper 2.

Kurta, A. and J. Kennedy. 2002. The Indiana bat: biology and management of an endangered species. Bat Conservation International, Austin, Texas. 253 pp.

Lacki, M. J., and J. H. Schwierjohann. 2001. Day-Roost Characteristics of Northern Bats in Mixed Mesophytic Forest. Journal of Wildlife Management. Volume 65 (3): 482-488.

LaVal, Richard K et al. "Foraging behavior and nocturnal activity patterns of Missouri bats, with emphasis on the endangered species Myotis grisescens and Myotis sodalis." Journal of Mammalogy (1977): 592-599.

Mamm, J. (1981). “Correspondence of food habits and morphology in insectivorous bats.” Journal of Mammalogy.

Mitchell, W. A., and Martin, C. O. (2002). “Cave- and crevice-dwelling bats on USACE projects: Gray bat (Myotis grisescens),” EMRRP Technical Notes Collection (ERDC TN-EMRRP-SI-25). U.S. Army Engineer Research and Development Center, Vicksburg, MS. www.erdc.usace.mil/el/emrrp

National Mitigation banking Association. “ http://mitigationbanking.org/mitigationbanks/index.html ” (accessd 2/26/2015)

Sewell, P., P. Roby, and M. W. Gumbert. 2006. Rare bat survey on the Cherokee National Forest, Tennessee. Final Report, U.S. Forest Service, Cleveland, Tennessee.

Trani, K. Margaret. “Maintaining Species in the South” USDA Forest Service. (http://www.srs.fs.usda.gov/sustain/draft/terra5/terra5.pdf)

Tuttle, M.D. 1976. Population ecology of the gray bat (Myotis grisescens): factors influencing growth and survival of newly volant young. Ecology, 57:587-595. (USFWS) United States Fish and Wildlife Service. 2013. 2013 Revised Range-wide Indiana Bat Summer Survey Guidelines.

U.S.F.W.S., (2011). “A National Plan for Assisting States, Federal Agencies, and Tribes in Managing White-Nose Syndrome in Bats.” US Fish and Wildlife Service, 300 Westgate Center Drive, Hadley, MA 01035.

U.S.F.W.S., (2015) “U.S. Fish and Wildlife Service Protects Northern Long-eared Bat as Threatened Under Endangered Species Act.” Midwest Region, 5600 American Blvd W, Suite 990, Bloomington MN 55437.

Website sources

White Nose syndrome reference page

http://www.georgiawildlife.com/WNS , accessed 4/23/2015

Myotis Septentrionalis reference page: http://www.fws.gov/midwest/endangered/mammals/nlba/nlbaFactSheet.html (Updated January 2015)

Myotis sodalis reference pages:

http://www.fws.gov/Midwest/Endangered/mammals/inba/index.html (Updated November 20, 2014) http://georgiawildlife.com/sites/default/files/uploads/wildlife/nongame/pdf/accounts/mammals/

myotis_sodalis.pdf (Updated September 2009)

Myotis grisescens reference pages:

http://www.georgiawildlife.com/sites/default/files/uploads/wildlife/nongame/pdf/accounts/mammals/ myotis_grisescens.pdf (Updated September 2009)

http://www.fws.gov/midwest/endangered/mammals/grbat_fc.html (Last updated: July 16, 2014)