Habitat Atlas for Wildlife at Risk
Spotted Bat
Euderma maculatum

• Length: 12 cm (slightly less than half is tail); wingspan: 35 cm.
• Enormous ears: approximately 4 cm in length.
• Weight: 18 grams.
• Fur on back is black with three large white spots located on each shoulder and rump; patch of white hair at base of each ear.

Status:

British Columbia Blue List
Canada: Vulnerable

Special Significance

The Canadian population of Spotted Bats appears to have remained at a relatively constant but low level for the past five years. The Spotted Bat is considered to be one of the rarest North American bats. This extremely shy creature roosts in cliffs, where it is very sensitive to human disturbance. Recognizing the rarity and vulnerability of this bat has resulted in its provincial and national designation as vulnerable. While Spotted Bats are known to be active in the Okanagan from late April until October, it is not known if they overwinter in British Columbia.

Distribution

• In British Columbia, found in the Okanagan, Thompson, Fraser and Chilcotin valleys to the Williams Lake region; also found in the Similkameen Valley and Cariboo region but is most common from Osoyoos to Penticton.

Habitat

• Forage in all types of habitats including open and dense coniferous forests, deciduous habitats, hay fields, marshes, riparian areas and dry shrub-steppe grasslands.
• Day roosts found in crevices of high steep cliff faces.
• Maternity roosts are in crevices of cliffs or canyon walls; cliffs are often greater than 100 metres high.
• Proximity of roosts to suitable feeding areas and a source of water is important.
• Hibernation sites may be in crevices of cliffs that are inaccessible to humans or bats may spend winters outside the province.
• Prefer areas of low human activity.

Reproduction

• Mating is believed to take place in autumn.
• Females are able to reproduce at one year of age; they produce one offspring a year with young born in late June or early July.

Food Habits

• Leaves its day roost 30 to 60 minutes after sunset.
• Generally solitary, bats follow a set route to a night-time feeding area and return to the same roost night after night.
• Specialized feeder subsisting mainly on moths captured while flying 5 to 15 metres above the ground; caddis flies and beetles are also consumed.
• Large ears are held erect during flight and may allow long-range prey detection.
• Low frequency call may enable bat to avoid detection by certain species of moths that can "hear" ultrasonic sonar calls of bats.

Interesting Facts

• Like other British Columbian bats, Spotted Bats emit echolocation calls to navigate in the dark, locate prey and possibly to advertise to other bats; however, it is the only bat in Canada whose echolocation calls are audible to the human ear.
• Not very social and do not form large hibernating colonies typical of many other kinds of bats; social interactions seem to be restricted to mating and mother-infant care.
• In very high temperatures, blood flow to ears and wing membranes increases to aid body cooling.
• Slow fliers due to rounded wing shape and relatively heavy body in relation to surface area of wing; very agile despite slow speed; are able to leap into flight from ground.

References

1. Nagorsen, D.W. and R.M. Brigham. 1993. Bats of British Columbia. Royal British Columbia Museum Handbook, Victoria, British Columbia.
2. Blood, D.A. 1993. Spotted Bat; Wildlife at Risk in British Columbia. Brochure. Ministry of Water, Land and Air Protection, Victoria, British Columbia.
3. Garcia, P.F.J., S.A. Rasheed and S.L. Holroyd. 1995. Status of the Spotted Bat in British Columbia. Ministry of Water, Land and Air Protection, Lands and Parks, Victoria, British Columbia