Townsend’s Big-eared Bat This vulnerable species is very sensitive to human disturbance. Ministry of Environment, Lands and Parks In view of its apparently small prov- on the Red List, which are being consid- incial population size, vulnerability to ered for legal designation as Threatened disturbance and low reproductive rate, or Endangered. Like other bats, this the future of this little-known bat in species receives general protection Why are Townsend’s British Columbia is indeed uncertain. against harassment, killing or posses- Big-eared Bats at risk? sion under the British Columbia Wild- ownsend’s Big-eared Bats are at risk What is their status? life Act. However, most habitats used by because they are confined to small ownsend’s Big-eared Bats have a these valuable animals do not currently regions of suitable habitat at low ele- broad distribution, including most receive any effective protection. T vations in the southern part of of Mexico and the Western United British Columbia – precisely the areas T States. However, populations are What do they look like? that humans prefer to occupy. Also declining in many areas and the species ownsend’s Big-eared Bat – Coryno- known as the Lump-nosed Bat or has been designated as endangered, rhinus (Plecotus) townsendii – is eas- Western Big-eared Bat, this species is threatened or of special concern ily distinguished from other British sparsely distributed across its range. throughout most of its range. In T Columbia bats by its enormous ears, Townsend’s Big-eared Bats are particu- California, for example, this bat was once which measure about half its body larly vulnerable to disturbance by peo- common, but its numbers have decl- length, and the two fleshy protrusions on ple. Like many other bat species, ined sharply and the its muzzle. These account for its com- in summer they form maternity species is now consid- mon names of “big-eared” or “lump- colonies, often in buildings, and The species ered uncommon. nosed” bat. The fleshy projections on the in winter they gather together to Many known mater- nose, known as pararhinal glands, may hibernate in caves or mines. has been nity colonies in lime- function as sexual scent glands. The large However, when roosting in these designated stone caves in ears of this bat probably have several sites, Townsend’s Big-eared Bats California have been functions, the most important of which do not hide in crevices like many of special abandoned, although is to funnel sounds into the ear canal. bats do and so are very suscepti- concern other maternity sites The ears also have an abundant blood ble to intrusions or vandalism. In exist in mines and supply and assist in the regulation of British Columbia, no hiberna- throughout buildings. At many body temperature. In flight, the ears are tion sites and only one maternity most of its former colony loca- directed forward in plane with the body, colony are protected from tions in Oregon, this leading some researchers to suggest that human entry. Disturbance of range. species is no longer they may also provide lift during flight. females with young can severely found or occurs in Two other British Columbia species, lower breeding success. Repeated distur- reduced numbers. the Spotted and Pallid bats, also have bance at winter hibernacula can cause In British Columbia, only a few very large ears. However, the Spotted energy loss, abandonment of the caves maternity colonies, totalling about 350 Bat is readily distinguished by its promi- and death. bats, have been documented. About 16 nent black and white markings, and Various land use or industrial coastal and interior hibernation sites the Pallid Bat by its lighter colour and activities near bat colonies or in their have been discovered, but 14 of these ears that are not joined at their bases. foraging areas can adversely affect had 6 or fewer bats when surveyed and In addition, the Spotted and Pallid Townsend’s Big-eared Bat. Insecticide the largest colony numbered only 48; bats are both larger than Townsend’s spraying on agricultural or forest our total known winter population is Big-eared Bat. lands is of particular concern, because less than 100 bats. Although additional The long fur on the back of Town- it destroys the bat’s food supply. undiscovered colonies probably exist, send’s Big-eared Bat varies from pale Like other bats, this species has a the total provincial population of this brown to blackish-grey, while the hairs very low reproductive rate. Females bat is likely very small. in the underfur are paler. Male and bear only one young per year. Thus, In view of the rarity and vulnera- female big-eared bats have similar even low rates of mortality caused by bility of Townsend’s Big-eared Bat, it colouring. Bats from coastal areas tend people, when added to natural losses has been placed on British Columbia’s to be darker than bats from the interi- can result in population declines and Blue List. Blue-listed species are con- or of the province. The tragus or ear- eventual elimination of local colonies. sidered vulnerable, in contrast to those let, an erect fleshy structure found at are good for mother bats and their young. Delayed fertilisation occurs in most bats that live in north-temperate areas. Bats are the only mammals that employ this reproductive strategy. In spring, the pregnant females move to summer maternity colonies that are usually within a few kilometres of the hibernaculum. They show great site fidelity, returning to the same loca- tion each year. Here, the young bats, naked at birth, are born and nursed. During summer, the males do not associate with the maternity colonies and are believed to roost singly in scat- tered locations. They play no part in raising the young. In the United States, nursery col- onies typically contain 50 to 150 bats and are found in mine shafts, caves or buildings. The known maternity sites in British Columbia – located in attics, barns and a military bunker – house 25 to 100 bats. Buildings may be the base of the ear in all bats, is about hibernating colonies, which include preferred in British Columbia because one-third of the ear length and point- both sexes, the bats usually hang singly bats need warm sites to promote devel- ed in this species. or in small groups from cave walls or opment of their young and caves here Compared to other British Columbia roofs. When in a state of hibernation may be too cold. bats – which have wing-spans ranging or torpor (a short-term, hibernation- The gestation period of Townsend’s from about 22 centimetres in the dimin- like state) the ears are coiled like a Big-eared Bat is a utive California Myotis to 40 cm in the ram’s horn, the wings are folded In variable 56 to 100 Hoary Bat – Townsend’s Big-eared Bat and the fur is erected to give max- days, depending on is a medium-size species. It has a wing- imum insulation. maternity the temperature in span of about 30 cm, a total length of colonies the the maternity site. 10 cm and a weight of 8½ grams, only How do they reproduce? Cold temperatures 1½ g more than a one-dollar coin. The ownsend’s Big-eared Bats mate females cause torpor in preg- surface area of a Townsend’s Big-eared in autumn and early winter at form tight nant females, which Bat’s wings is large relative to its body their hibernation sites, the only slows foetal devel- weight. This gives these bats an excep- T place where the two sexes com- clusters to opment. Only a tional capacity for manoeuvrable flight monly occur together. Breeding is preserve single offspring is and the ability to fly at low speeds and accompanied by ritualistic vocali- produced by each to hover. Straight-line flight speeds of sations and head nuzzling. Sperm body heat. female, but usually about 3 to 6 metres per second have is stored all winter in the female 90 to 100 percent been reported. reproductive tract, and ovulation and of the females produce young. Births Like all bats, Townsend’s Big-eared fertilisation do not occur until spring. in British Columbia are believed to Bats have five claws on each hind foot, With this unusual strategy, called delayed occur from late June to mid July. The which they use to hang head-down fertilisation, mating takes place when the young bats are large at birth: 25 per- when roosting. In maternity colonies, adults are in peak physical condition, but cent of the weight of the adults! They the females form one or more tight pups are not born until early the next grow extremely fast and are capable of clusters to preserve body heat. In summer when foraging conditions flight at a remarkable 2½ to 3 weeks of age. They reach adult size in one used to locate the insects on which it Present range of month and are weaned at about 6 feeds. It is able to emit echolocation Townsend’s Big-eared weeks. After the maternity colonies pulses through its nose almost as well as Bat in Canada and the United States break up around August and the from its mouth, an unusual trait in bats. newly independent pups begin learn- The low intensity sounds this bat ing to forage for themselves, natural produces enable it to locate and “glean” mortality of young bats is high. insects from vegetation or other sur- Hibernation is another challenge; faces, although most insects are proba- probably only 40 to 50 percent sur- bly captured in the air.