The California Myotis is one of our smallest species. Its fur colour varies from rusty to blackish brown and is dull, lacking a glossy sheen. Its ears and its wing and tail membranes are black. The ears extend beyond the nose when pushed forward; the tragus is long and narrow. The length of the naked area on the snout is roughly equal to the width across the nostrils. The hind foot is small; the calcar has a prominent keel. The small, delicate skull has a steeply sloping forehead.
In south-central British Columbia, the California Myotis can be confused with the Western Small-footed Myotis (Myotis ciliolabrum), but the latter has paler fur that contrasts more sharply with the black wings, face and ears, and it has a longer bare area on its snout. In other parts of the province the small size (forearm less than 36 mm), small foot and keeled calcar will readily distinguish the California Myotis from other Myotis species. The small skull (less than 3.4 mm postorbital width) separates this bat from all other species of Myotis except the Western Small-footed Myotis. The skull of the California Myotis has a more steeply sloped forehead than the skull of the Western Small-footed Myotis.
total length: 80 (65-95) n = 75 tail vertebrae: 36 (26-41) n = 77 hind foot: 6 (5-9) n = 80 ear: 13 (8-15) n = 40 tragus: 4 (4-8) n = 35 forearm: 32.1 (29.4-35.0) n = 68 wingspan: 222 (209-251) n = 28 weight: 4.4 (3.3-5.4) n = 26
Mating occurs in autumn; females produce a single young. The breeding biology of this bat in British Columbia is poorly documented. There are records of pregnant females in the interior from 11 June to 26 June and on Saltspring Island on 6 June, suggesting that young are born in late June or early July.
Studies in the Okanagan Valley revealed that the California Myotis emerges shortly after dusk. There are two peaks in hunting activity: between 10:00 and 11:00 pm and between 1:00 and 2:00 am. It hunts mostly over lakes near the surface, although this species will forage in the tree canopy, especially in poplar groves. In the Okanagan, the diet is predominately caddisflies, with moths, flies and beetles minor food items. Food habits in other parts of the province have not been studied.
This species uses rock crevices, tree cavities, spaces under the bark of trees, mine tunnels, buildings and bridges for summer day roosts. Small maternity colonies have been found in similar locations. This bat is particularly flexible in its choice of night roosts and it will use almost any natural or man-made shelter. Males live separately from females in summer and often appear to change their roosting locations.
There are several winter records for the coast, from Vancouver Island and in the Vancouver area. One Vancouver record was of an individual flying inside a building in January at the University of British Columbia. Insect remains were present in its stomach suggesting that it had recently fed. In coastal Washington and Oregon, where the California Myotis frequently hibernates in buildings, there is considerable evidence that it occasionally emerges from torpor to feed. No hibernating colonies have been recorded in the interior of the province, but there are winter museum specimens from Hope (January), Okanagan Landing (March) and Rogers Pass, Glacier National Park (January).
In British Columbia, this species inhabits arid grasslands, humid coastal forests and montane forests. Its elevational range is from sea level on the coast to 1280 metres in Glacier National Park.
A western bat, its range extends from southern Mexico to British Columbia and southeastern Alaska. In British Columbia, it inhabits several coastal islands including Vancouver Island and the Queen Charlotte Islands, the coastal mainland north to the Bella Coola Valley, and the interior north to Wells Gray Provincial Park and east to Kootenay National Park.
Two subspecies are found in the province: M.c. caurinus, a dark coastal race ranging from California to Alaska, and M.c. californicus, a paler race that inhabits the western United States and the southern interior of British Columbia.
This bat is common in British Columbia. Although it has been studied in the Okanagan Valley, its biology in other regions, particularly the humid coastal forest, is virtually unknown.
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:
2023-09-24 10:14:18 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.