The Western Long-eared Myotis is a large Myotis species with long ears extending 5 mm or more beyond the nose when pushed forward. Its dorsal fur colour is extremely variable, ranging from yellowish brown in the interior of the province to dark brown or nearly black in coastal areas. Blackish brown shoulder patches are usually evident but they can be indistinct on dark individuals. The outer edge of the tail membrane has a fringe of tiny hairs that can be seen with a hand lens. The ears and flight membranes are nearly black and usually contrast sharply with the paler fur. The tragus is long and slender with a small lobe at its base. The calcar lacks a distinct keel. The skull has a relatively broad interorbital area and a gradually sloping forehead.
Three other long-eared Myotis species are found in British Columbia: Keen's Long-eared Myotis (Myotis keenii), the Northern Long-eared Myotis (Myotis septentrionalis) and the Fringed Myotis (Myotis thysanodes). All have ranges that overlap with that of the Western Long-eared Myotis. The Fringed Myotis can be readily distinguished by the fringe of hairs on the tail membrane and by the longer forearm (greater than 40 mm). To distinguish the Western Long-eared Myotis from Keen's Long-eared Myotis and the Northern Long-eared Myotis using external features see their species accounts. The skull of the Western Long-eared Myotis has a longer toothrow than that of Keen's Long-eared Myotis and the Northern Long-eared Myotis: the distance from the last upper premolar to the last upper molar is greater than 4.2 mm.
total length: 92 (74-103) n = 54 tail vertebrae: 42 (31-50) n = 51 hind foot: 9 (7-11) n = 51 ear: 20 (17-22) n = 31 tragus: 10 (8-12) n = 21 forearm: 38.4 (36.0-42.0) n = 47 wingspan: 271 (243-294) n = 21 weight: 5.5 (4.2-8.6) n = 25
Reproductive data for the province are also scanty, consisting of anecdotal observations and information on museum specimens. Mating presumably occurs in autumn or early winter; females produce a single young. Pregnant females were found in a maternity colony at Vermilion Crossing, Kootenay National Park, between 28 June and 7 July. In the Okanagan Valley, females with near-term foetuses were collected on 27 and 28 June, and nursing females were observed from 5 July to 13 August. These data suggest that, in the interior, young are born in late June or early July. No reproductive data are available for coastal British Columbia. Newborn Western Long-eared Myotis are furless and weigh 1.0-1.5 grams.
Western Long-eared Myotis typically emerge 10 to 40 minutes after dark to feed. It is quite flexible in its feeding behaviour, eating airborne insects as well as gleaning insects from vegetation or off the ground. Food habits have not been studied in British Columbia; in other regions, it is known to prey mainly on moths, as well as beetles, flies and spiders. Robert Barclay has suggested that bat's flexible feeding behaviour enables females to breed successfully in high, cool sites where flying insects are scarce. Its quiet, short-duration, high-pitched echolocation calls are an adaptation for hunting in habitats with heavy vegetation. Furthermore, these calls are not readily detected by most moths. When closing in for an attack, the Western Long-eared Myotis often stops calling and listens for sounds produced by its prey. Moths may be especially vulnerable to predation by the Western Long-eared Myotis because their fluttering is audible.
In summer the Western Long-eared Myotis uses buildings or under the bark of trees as day roosts; there are also a few records of this species roosting in caves, sink holes and fissures in cliffs. Maternity colonies, usually located in buildings, are generally small (5 to 30 individuals) and may contain a few adult males. Caves and mine adits are used as temporary night roosts.
There are no winter records for the province; in fact, this bat's winter biology is poorly documented throughout its range. In the western United States, a few individuals have been found hibernating in caves and mine adits and there is a December record from coastal Oregon of an individual that was found in a garage.
This species is found in a wide range of habitats in the province, from arid grasslands and ponderosa pine forests to humid coastal and montane forests. Its elevational range in British Columbia extends from sea level on the coast to 1220 metres in the Cascades (Manning Provincial Park) and Rocky Mountains (Kootenay National Park). This is one of the few bats found consistently at high elevations in western Canada. In the Kananaskis region of the Alberta Rockies, summer populations consisting of both sexes live at 1350 to 2050 metres.
This is a western bat that ranges from Baja California through the western United States to Saskatchewan, Alberta and British Columbia, where it occupies the entire mainland as far north as the Bella Coola Valley on the coast and the Prince George region in the interior. It also inhabits Vancouver Island but appears to be absent from the Queen Charlotte Islands.
Two subspecies occur in the province: M.e. pacificus, a dark coastal race ranging from California as far north as the Bella Coola Valley in British Columbia, and M.e. evotis, a paler, larger race that inhabits Mexico, the western United States and western Canada. In British Columbia, it is found in the south-central interior north to the Prince George region.
Despite its widespread distribution in the province, remarkably little is known about the basic biology of this species particularly in the coastal forests. A published record from the Okanagan reports that a dead Western Long-eared Myotis was found in the mouth of a snake, a Western Yellow-bellied Racer.
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2021. E-Fauna BC:
Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab
for Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
2022-01-16 3:06:25 AM]
The information contained in an
E-Fauna BC atlas pages is derived from expert sources as cited (with permission) in each section.
This information is scientifically based. E-Fauna BC also acts as a
portal to other sites via deep links. As always, users should refer to
the original sources for complete information. E-Fauna BC is not
responsible for the accuracy or completeness of the original information.