Some selected photos of bats we caught in Portal, AZ with Bat Conservation International
Silver Haired Bat
A blog about the bats of the North Country.
Common Name: Big Brown Bat
Scientific Name: Eptesicus fuscus
Classification: Kingdom Animalia, Phylum Chordata, Subphylum Vertebrata, Class Mammalia, Order Chiroptera, Family Vespertilionidae, Genus Eptesicus, Species Eptesicus fuscus
Physical Description: Big brown bats have an average mass of 23g and an average total body length of 110 to 130mm. The wingspan of the big brown bat is on average 330mm wide. Average forearm length for big brown bats ranges from 41-50mm. The hind foot length of the big brown bat ranges from 10-14mm and ear length ranges from 16-20mm. Big brown bats are sexually dimorphic and females are usually slightly larger than males. Big brown bats have a keeled calcar and the tail extends about 3mm beyond the tail membrane. The pelage of big brown bats is soft with a freshly “shampooed” look. Pelage is slightly oily and ranges from pinkish tan to rich chocolate. Longer hairs have shiny tips and the ventral pelage has a paler tone. Ears, wings, and tail membrane maintain a dark brown to black coloration.
Geographic Range: The big brown bat has a very large range extending from southern Canada south through temperate North America, and through Central America to the northwestern limit of South America. Big brown bats are also resident in the Bahamas and the Greater Antilles.
Conservation Status: Big brown bats are fairly common and the IUCN considers the big brown bat a species of least concern.
Habitat: Big brown bats are commonly found roosting within manmade structures. In fact maternity colonies are typically found in churches, barns, and houses. Once inside houses big brown bats tend to prefer to roost in double boxed walls and boxed in eaves. Other than manmade structures big browns tend to roost in large hollow oak, beech, and sometimes even dead ponderosa pines. Foraging big brown bats are habitat generalists with no known preference for over water or over land sites, type of canopy cover, or edge versus non edge habitat.
Diet: Big brown bats are insectivorous and mainly feed on beetles. Other smaller components of the big brown bat diet include moths, flies, wasps, and dragonflies. Juvenile big brown bats tend to eat softer foods such as moths.
Reproduction: Big brown bats breed between September and March. Hibernating females are able to delay fertilization until after arousal in the spring. Females form maternity colonies during the spring varying in size from 5-700 individuals. The gestation period of the big brown bat is about sixty days. In the beginning of April females give birth to one or two pups. Females must consume at least their body weight each night while nursing and so they leave behind juveniles at the roost to forage. Males do not take part in raising the young. Young big brown bats produce squeaking calls that can be heard from thirty feet away; these calls help females locate their young. Juveniles develop very quickly; time to weaning is 18-35 days. Pups are typically able to fly by July. Big brown bats reach sexual maturity at on average 730 days of age.
Ecology and Behavior: Big brown bats use echolocation to capture insects and to avoid objects while they fly. Typical big brown bat echolocation pulses range from 48-27kHz. It is suggested that big brown bats actually orient themselves towards the largest natural sound field in order to detect areas with the highest density of prey, for example a large number of katydids. During the winter months big brown bats hibernate in natural and manmade structures. Big brown bats are very hardy and can tolerate colder temperatures that other bats cannot withstand. To date it is believed that big brown bats are capable of hibernating for 300 to 340 days, proven experimentally when scientists put a big brown bat in a refrigerator with only water to drink.
Goehring, H. February 1972. Twenty-Year Study of Eptesicus Fuscus in Minnesota. Journal of Mammalogy, Vol. 53, No.1: pp. 201-207.
Kurta, A., R. Baker. 26 April 1990. Eptesicus fuscus. Mammalian Species: No. 356, pp.1-10.
Mulheisen, M. and K. Berry. 2000. “Eptesicus fuscus” (On-line), Animal Diversity Web. Accessed July 17, 2010 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Eptesicus_fuscus.html.
Tags: Big Brown Bat
Common Name: Silver Haired Bat
Scientific Name: Lasionycteris noctivagans
Classification: Domain Eukarya, Kingdom Animalia, Phylum Chordata, Subphylum Vertebrata, Class Mammalia, Order Chiroptera, Family Vespertilionidae, Subfamily Myotinae, Genus Lasionycteris, Species Lasionycteris noctivagans.
Physical Description and Identification: Silver haired bats are of medium size weighing from 8 to 12 grams. Total length of silver haired bats ranges from 90 to 115 millimeters, tail length ranges from 35 to 50 millimeters, wingspan length ranges from 270-310 millimeters, forearm length ranges from 37 to 44 millimeters, and right hind foot length ranges from 6 to 12 millimeters long. Silver haired bats may be identified by their dark, silver tipped fur. Fur is typically black however some individuals have dark brown fur with yellow tips. The ears of the silver haired bat are short at about 15 to 17 millimeters in length, rounded, and completely lacking fur. The tragus of the silver haired bat is blunt and curved forward. The interfemoral membrane of the silver haired bat is slightly furred on the dorsal surface unlike many other North American bats. The tail of the silver haired bat is 50 to 75 percent naked. Silver haired bats exhibit sexual dimorphism as females are larger than males. The silver haired bat resembles the larger hoary bat, but silver haired bats are decisively smaller, hoary bats range from 99 to 140 millimeters in length and weigh from 20 to 35 grams.
Geographic Range in North America and New York State: In North America the silver haired bat’s range encompasses southern Alaska and southern Canada, throughout the United States with the exceptions of southern California, southern Arizona, Florida, and the southern borders of Georgia, Mississippi, Arkansas, and Louisiana. The silver haired bat may be found throughout the entirety of New York State.
Conservation Status: According to the IUCN red list the silver haired bat is a species of least concern, and the United States federal list gives the silver haired bat no special status. The New York State DEC does not give the silver haired bat any special status and also recognizes the silver haired bat as one of the most common bats in the Adirondacks.
Habitat: Silver haired bats are typically found in temperate northern hardwood habitats which are located close to ponds and streams. Silver haired bats roost behind loose tree bark during the day and tend to prefer willow, maple, and ash due to the deep fissures in the bark of these trees. Silver haired bats will sometimes roost in snags and empty birds’ nests, as well as the occasional open shed or garage. During winter silver haired bats seek shelter inside trees, rock crevices, and buildings.
Diet: The silver haired bat is an insectivore. Silver haired bats have a diet consisting mainly of beetles, moths, and flies. Silver haired bats also feed opportunistically on other insects encountered during feeding. Silver haired bats most often feed over woodland ponds and streams; however silver haired bats do not always feed in mid flight. Some silver haired bats forage on the ground occasionally and silver haired bats have been observed feeding on larvae inside trees.
Reproduction: The breeding season of silver haired bats occurs in autumn. Courtship and mating occur when males and females come together during the autumn migration. Male and female silver haired bats are sexually mature at 152 days of age. After mating occurs; females store sperm inside their reproductive tracts and delay fertilization until the next spring. The gestation period of the silver haired bat lasts from 50 to 60 days. Parturition occurs while the female roosts upside down. A female in the process of parturition will bend her uropatagium upwards and the tail membrane serves as a basket to catch the young. Young are born in late June to early July and the average number of offspring each female produces is two. Newborn silver haired bats are born with closed eyes, folded ears, and most of their 22 teeth in place. On average young silver haired bats are weaned within 36 days. Silver haired bats live for twelve years in the wild on average.
Ecology and Behavior: Silver haired bats play an important role in the ecosystem as consumers of insects. Silver haired bats consequently affect humans because silver haired bats play an important role in pest control. Predators of the silver haired bat include striped skunks and great horned owls.
Silver haired bats may play be considered a nuisance to some humans because many humans are afraid of bats, and some bats are occasionally linked to transmission of rabies to humans.
Silver haired bats are usually solitary, only occasionally found in small groups or pairs. During the summer months silver haired bats occur in ranges that are segregated by sex, however during late summer and autumn groups of both sexes come together and migrate to the southern part of the bats range and breed before hibernating. Some silver haired bats have been seen to hibernate in northern regions as well.
Silver haired bats are known to be one of the earliest flying species of bat during the evening. Silver haired bats may even be seen flying in broad daylight. Silver haired bats are known to time their flight so that it will not conflict with the flights of other bat species in the area such as the hoary bat or big brown bat. Silver haired bats fly at a speed of 4.8 to 5 meters per second, one of the slowest flying North American Bats.
Silver haired bats have acute hearing and they use echolocation to locate prey items. Silver haired bats communicate with one another using sound. Most notably, baby bats are known to emit high pitched chirps when separated from their mothers.
Kays RW, Wilson DE. 2002. Mammals of North America. Princeton (NJ) : Princeton University Press. p. 144.
Naumann R. 1999. “Lasionycteris noctivagans” (On-line), Animal Diversity Web. Accessed December 04, 2009 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lasionycteris_noctivagans.html.
Nowak, Ronald M., 1994, Walker’s Bats of the World, Johns Hopkins University Press.
Stegmann A, Hicks R. 2008, “Bats of New York”. [Internet]. [Updated 2008]. New York (NY) New York State Department of Environmental Conservation. [Cited 04 Dec, 2009]. Available from : http://www.dec.ny.gov/pubs/46905.html
Tags: Silver Haired Bat
In June of 2010 Dr. Barthelmess and I traveled to Portal, Arizona to take part in a program by Bat Conservation International. We spent a week in the Chiricahua Mountains learning about all things batty. The program was led by Janet Tyburec, John Chenger, Tim Snow and Dr. Cullen Geiselman. During the warm Arizona days we spent several hours per day in lecture learning about bats. Some of the topics covered included general bat ecology, an update on White Nose Syndrome, and current threats to bats. We also learned about how to asses habitat used by bats. For example, water features are very important in a bat’s habitat and bats with different wing types use different types of water features. Faster, less maneuverable bats are less able to make use of smaller water sources. Being able to assess habitat is important because it enables a researcher to set up traps such as mist nets and harp traps in areas where a bat is most likely to be caught. It is also important to be able to assess habitat so that when netting bats, one can recognize where different types of bats are most likely to be caught. We also learned about the most recent methods for acoustic monitoring. In our lab we use a direct recording device, the AR 125, and it was interesting to learn about heterodyne recorders and time expansion recorders. Ultimately the lecture portion of the program was a great supplement to the field experience we had at night trapping bats.
All of our evenings in Arizona were spent trapping and observing bats. There are twenty eight species of bat in Arizona and we were able to trap fifteen species. Over the course of the week we had 382 captures. The first evening we were able to observe two species of nectar feeding bats; Choeronycterus mexicana and Leptonycteris nivalis feeding at the many hummingbird feeders present at the Southwest Research Station. We used an infrared camera to see the animals feeding and could also use the camera to slow down video so that we could see their long tongues and distinctive tail membranes.
The remainder of the week we spent strictly trapping animals. Participating in this workshop was helpful because Dr. Barthelmess and I were able to practice the new White Nose Syndrome protocol in an area where WNS is not yet a threat. Anyone who handled a bat had to wear latex gloves and the latex gloves had to be changed between each bat. Disposable bat bags were used to hold all bats except hoary bats. Non disposable bat bags could only be used for one animal before they had to be re-disinfected using a bleach solution. Bats are trapped in two main ways, using mist nets and harp traps. A mist net is a very fine net often used by ornithologists to trap birds. Nets range in height up to 30 m in the air for a triple high mist nets. Bats have a hard time detecting these nets and become trapped in the pockets of the net. Harp traps are made of fine wires arranged in a manner that looks like a harp. Bats hit the wires and fall into a collection bag. After each trapping night we had to disinfect the nets and net bags as well as the harp traps with bleach solution to prevent the spread of any fungal spores.
Our trapping experience was a unique one because we were trapping very close to a forest fire and caught an interesting array of animals that we may not have otherwise caught. For example out of the 382 bats we caught, 166 of them were hoary bats, Lasiurus cinereus. Hoary bats were definitely some of the more charismatic individuals we caught, when caught they were very vocal and it seemed like they could open their mouths nearly 180 degrees as they violently flopped around. Other species of myotis were much quieter and far more cooperative. Over the course of the week Dr. Barthelmess and I were able to practice identifying the many animals we caught to species. There is nothing like having the animal in hand while practicing species ID, it really was a crash course. It was amazing to see the many differences that the few species we examined possessed. For example the Mexican free tailed bat, Tadarida brasiliensis had wrinkly lips and resembled a newborn puppy. The pallid bat, Antrozous pallidus had large ears and many of the individuals we found had scars on their wings and even holes or recent breaks due to scuffles with large prey items like centipedes and scorpions. We were lucky enough to catch one yellow bat, Lasiurus xanthinus and see its beautiful light pelage and pink skin. Bats ranged in size from the large hoary bat to the tiny pipistrelle. Different species also behaved differently and we were able to learn some of their idiosyncrasies. Big brown bats (Eptesicus fuscus) with their shiny coats and dog like faces were much more aggressive than the quieter Myotis californicus. Overall we gained extremely valuable knowledge about trapping bats and a stronger love for these remarkable animals.
The summer months provide an optimal opportunity to survey the populations of bats in St. Lawrence County. At dusk the 9 species of bats in St. Lawrence County depart their daytime roosts to forage throughout the night. Insectivorous bats use echolocation to detect, locate, and discriminate prey. The majority of these bats use a frequency modulated (FM) signal that sweeps from high to low frequency. These frequency modulated calls provide the bat with information regarding prey location, size, and shape (Barclay et. al 1994). Other bats also use constant frequency (CF) calls to detect fluttering prey set against a stationary background (Barclay et. al 1994). Different species of bats may be identified by their echolocation calls. Each species exhibits differences in echolocation calls such as changes in frequency composition, changes in frequency per unit time, duration of pulse, and repetition rate (Kunz et. al 1996). Ultrasonic bat detectors make it possible to record bat echolocation calls at night. Ultrasonic bat detectors also allow researchers to identify different microchiropterans as well as determining relative abundance at foraging sites (Kunz et. al 1996). Currently ultrasonic bat detectors are one of the most effective ways to determine relative abundance of bats in the largest study areas in most timely fashion (Roche et. al 2006). Our project involves the use of an ultrasonic bat detector to determine the relative abundance of the 9 species of bats found in St. Lawrence County.
Bat calls seen ultrasonically.
Our ultrasonic detector is used on road surveys. The AR 125 detector is kept inside a housing which is mounted on a large magnet. The detector can then be placed on the roof of the car and information from the detector is fed from outside to a laptop. We have plotted several routes throughout St. Lawrence County including different habitats such as evergreen, deciduous, and agrarian habitats and we conduct road surveys along these routes. Surveys take place starting at twilight and each route takes about an hour and a half to drive. The driver must drive at a speed between 15 and 20 mph to minimize interference with the detector. With this methodology the surveyor has the ability to detect hundreds of bats per night. Road surveys using ultrasonic detectors are an excellent way to detect bats that otherwise would not have been detected during a mist netting survey. Road surveys are also a good way to cover wide stretches of habitat in a short period of time.
Barclay RMR and Brigham RM. 1994. Constraints on optimal foraging: A field test of prey discrimination by echolocating insectivorous bats. Anim Behav 48(5):1013-21.
Kunz TH, Thomas DW, Richards GC, Tidemann CR, Pierson ED, Racey PA. 1996. Observational techniques for bats. Measuring and Monitoring Biological Diversity: Standard Methods for Mammals :105–114.
Roche N, Langton S, Aughney T, Russ J. 2006. The car-based bat monitoring scheme for Ireland: Report for 2006. Weather 9.
Common Name: Indiana Bat
Scientific Name: Myotis sodalis
Classification: Kingdom Animalia, Phylum Chordata, Subphylum Vertebrata, Class Mammalia, Order Chiroptera, Family Vespertilionidae, Genus Myotis, Species Myotis sodalis
Physical Description: The Indiana bat ranges in length from 73 to 100mm in length. Indiana bats typically weigh between 6 and 11g. Forearm length for the Indiana bat ranges from 36.0 to 40.6mm, ear length ranges from 10.4 to 14.8mm, and the hind foot of the Indiana bat is a distinguishing characteristic as it is smaller than other species of myotis at 9mm. The tragus of the Indiana bat is short and blunt, measuring less than half of the length of the ear. The dorsal pelage of the Indiana bat ranges from black to light brown, however it usually appears as a dull chestnut gray. The ventral pelage is slaty at the base and grayish white at the tips with a cinnamon brown tint which gives the fur an overall pinkish white appearance. The Indiana bat is most likely to be confused with the little brown bat (Myotis lucifugus). Indiana bats may be distinguished from the little brown bat by their pelage and calcar. The Indiana bat has dull pelage unlike the glossy pelage of the little brown bat. The little brown bat also has a prominently keeled calcar approximately 16.5mm long.
Geographic Range: Indiana bats are found throughout the cavernous limestone areas of the United States as well as areas north of the cave regions in the Midwestern and eastern United States. The western edge of the range stretches from the Ozark Plateau in Oklahoma to Iowa and southwestern Wisconsin. The eastern edge of the range stretches from New Hampshire to northern Alabama. The Indiana bat may be found throughout New York State with the exception of the northernmost portion of the state.
Conservation Status: The Indiana bat is listed by the USESA, the IUCN red list, and the state of New York as an endangered species. During the winter Indiana bats are restricted to very few hibernacula, making these populations extremely vulnerable to disturbances such as human interference, changing microclimate, as well as White Nose Syndrome. In fact only seven caves house 87% of the total known population if Indiana bats.
Habitat: Winter habitat for the Indiana bat includes caves and mines with cool and stable temperatures. There is little information known about the summer habitat of the Indiana bat. Females and young are believed to roost in hollow trees and underneath loose bark. The suggested foraging summer foraging habitat is the foliage of riparian and floodplain trees. It is unknown where males spend the summer months; however some males have been encountered near hibernacula during the summer.
Diet: The diet of the Indiana bat is mainly composed of soft bodied insects as well as some moths and beetles. Interestingly pregnant females have a diet of almost 90% soft insects, however during lactation females show a preference for moths with a diet of about 70% moths. During the latter part of the summer Indiana bats tend to shift their diets toward harder bodied insects.
Reproduction: Indiana bats breed once per year during the fall swarm around hibernation sites. Even though mating occurs during the fall, actual fertilization and implantation do not occur until the spring when the female leaves the hibernacula. Gestation in the Indiana bat is on average sixty days. Young bats are born from late June to early July. Each female gives birth to on average one offspring. Mothers nurse their young until their offspring reach independence at around 25 to 37 days. Inside maternal roosts warmer temperatures are known to promote faster development for the young. Indiana bats are known to live up to fourteen years in the wild.
Ecology and Behavior: Indiana bats are important predators of small insects. Indiana bats use echolocation to locate prey items. Echolocation calls are produced in short bursts and range from 95 kHz to 40 kHz. In the early fall Indiana bats swarm around hibernation sites, entering warmer parts of the caves and foraging at night. As winter approaches bats move to the colder parts of the cave to hibernate and during hibernation Indiana bats gather in clusters on flat surfaces within the hibernacula. Typically bats leave hibernation sites from April to June. During the summer males and females live separate from each other with females forming maternal colonies to raise young. Indiana bats take flight about a half an hour past sunset in order to forage and typically forage close to the canopy of the forest.
Newell, T. 1999. “Myotis sodalis” (On-line), Animal Diversity Web. Accessed July 01, 2010 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Myotis_sodalis.html.
Thomson, C.E. (25 May 1982) “Myotis sodalis.” Mammalian Species. The American Society of Mammalogists, 163.
U.S. Fish and Wildlife Service, D. 1991. “Indiana Bat” (On-line). U.S. Fish and Wildlife Service, Division of Endangered Species: Species Accounts. Accessed July 01, 2010 at http://endangered.fws.gov/i/a/saa08.html.
You may have noticed articles in the local newspaper with pictures of bats with a strange white coating on their faces and fur. You may also have heard of a neighbor who found a dead bat with papery wings and this same white coating. You may have even seen sickly bats flying erratically yourself. The culprit is known in the scientific community as Geomyces destructans, but you may know it better as White Nose Syndrome, or WNS.
White Nose Syndrome was first documented on February 16, 2006 at Howes Cave 52km west of Albany, NY when a caver photographed several bats with a suspicious white substance on their muzzles (Blehert et. al 2008). The caver also noticed several dead bats on the cave floor. In 2007 the NYSDEC became aware of several hundred dead bats in various caves, bats behaving erratically, and bats with white noses. Today the death toll of northeastern Vespertillionids is unprecedented. Hundreds of thousands of bats have died since the initial discovery of white nose syndrome in 2006. The US Fish and Wildlife service has collectively found sick, dying, and dead bats in hibernacula in ten states (Figure 1). In some of these hibernacula 90 to 100 percent of the bats are dying (USFWS 2010).
WNS is characterized as an ailment of hibernating bats. WNS was named for the appearance of white fungal growth around the muzzles, ears, and wing membranes of afflicted bats (Blehert et. al 2008). Bats exhibiting WNS may also have low body fat, fly during the day, and reside in cold parts of hibernacula (USFWS 2010). Bats are especially vulnerable to fungal infection because hibernation takes place in large groups in hibernacula. Inside the hibernacula it is easy for fungal spores to spread from one animal to the next. Biologists at both state and federal levels have been working since the discovery of WNS to determine the specific cause of death in affected bats, however the definite cause is not yet known. One hypothesis is that over the winter bats lose their fat reserves due to the fungal infection, causing the bats to rouse from hibernation too early and die (USFWS 2009). However there may be multiple undetermined causes of bat mortality related to WNS. One thing is certain, WNS is a deadly problem. The bats of New York State are suffering exceedingly large casualties. In a survey of 23 caves in 2009, 18 of which were in New York State, researchers found an alarming 91 percent decline in the number of hibernating bats (NYSDEC 2009). It is estimated that the Little Brown bat has declined by an average of 93 percent, an alarming decline as Little Brown bats make up about 85 percent of all of the bats in the Northeast (NYSDEC 2009). It is also estimated that the endangered Indiana bat has declined by 53 percent in numbers (NYSDEC 2009). These numbers reflect only some of the devastation caused by WNS.
In lieu of WNS it is important that the public becomes aware of bat conservation issues. Bats are at their most vulnerable during hibernation. Unfortunately many of the hibernacula used by bats in the Eastern United States are popular sites for tourists and cavers. Humans are one of the main vectors through which fungal spores can spread. Tiny spores can cling to nearly any surface. Shoes, clothing, and gear are one of the easiest ways for the fungus to spread from cave to cave. In order to prevent the spread of WNS to other hibernacula the human impact on caves must be minimized by limiting human traffic as well as the use of strict decontamination protocols. It is also important that efforts be taken to estimate the size of bat populations now. Before the appearance of WNS there was little information about many bat populations in the United States. It is impossible to know the effects of WNS without having any previous knowledge about bat numbers. Some of the ways scientists can study these populations are by conducting mist netting sessions, acoustic surveys, and counting bats in hibernacula.
Blehert DS, Hicks AC, Behr M, Meteyer CU, Berlowski-Zier BM, Buckles EL, Coleman JTH, Darling SR, Gargas A, Niver R. 2009. Bat white-nose syndrome: An emerging fungal pathogen? Science 323(5911):227.
DEC Survey Shows Bat Populations down 90 Percent in Caves Impacted by “White Nose Syndrome” – NYS Dept. of Environmental Conservation [Internet] [cited 2010 2/10/2010]. Available from: http://www.dec.ny.gov/press/61104.html .
USGS National Wildlife Health Center – White-Nose Syndrome (WNS) [Internet] [cited 2010 2/10/2010]. Available from: http://www.nwhc.usgs.gov/disease_information/white-nose_syndrome/ .
USFWS White Nosed Syndrome in Bats- Frequently asked questions. [Internet] [cited 2010 2/10/2010]. Available from: http://www.fws.gov/northeast/pdf/white-nosefaqs.pdf .
Tags: White Nose Syndrome