Bats of the Okanagan and Similkameen
Townsend's Big Eared Bat |
Fourteen species of bats live in the Okanagan and Similkameen valleys out of eighteen species that occur in Canada. The great bat diversity is due to the variety of habitats we have from rocky bluffs, to forests, lakes and grasslands. Each species has its favourite habitat and diet. The Pallid Bat hunts over sage and antelope-brush grasslands and the vineyards that have replaced this habitat. They feed on larger insects on the ground such as grasshoppers, June beetles, and even scorpions. The Big Brown bat is a common sight in summer foraging over forests, lakes and urban areas for moths, termites and flies, while the Little Brown Bat chases tiny midges and moths.
Several species of bats in the Okanagan are considered “at risk” because of their small populations. Finding roosting habitat and sites for maternal colonies are the factors that limit bat populations. Females roost in maternal colonies where they give birth to one young and feed them milk for a few weeks before the young learn to fly and feed on their own. Male bats roost alone or in small groups in rock crevices, trees or under eaves and other man-made structures. Some bats take a break to rest and digest their food at night and may visit a night roost for a short nap.
Bats are protected by the BC Provincial Wildlife Act. The Pallid Bat, Western Red Bat, Spotted Bat and Townsend’s Big-eared Bat are considered species at risk. Very little is known about where bats hibernate in our province. The black and white Spotted bat, roosts in the crevices of cliffs above Okanagan lakes. Its large ears are as long as its body and unlike most bats, its echolocation clicks are audible to human ears. It feasts on moths until late October then disappears. It may hibernate deep in cliff crevices but this is only speculation.
Hibernation
The Hoary bat, Silver-haired bat and Red bat are the only Okanagan migratory bats going out of the country. It is thought that other bats travel less than 50 kilometres to winter hibernation caves or rock crevices. Heading off to winter hibernation sites, mature bats will socialize and mate before going to sleep for six or more months. During hibernation their heart rate may slow to 5 beats per minute, they lose up to forty percent of their body weight, and their temperature may be only slightly greater than the surrounding air. Hibernation sites have high humidity and a temperature that stays above 4o Celsius. People are advised not to go into caves where bats are hibernating to prevent the bats from using precious energy trying to escape.
Spotted Bats by Michael Durham |
Bats in your home
Fall is a good time to make repairs to houses and sheds if you want to prevent bats from getting into structures. By now resident bats have gone to their winter quarters. If you know the entry points for bats using a building, cover the hole with a flap of duct tape or roofing paper. If a bat was inside, it could get out but the flap will prevent a bat from re-entering the structure. Remember that a bat only needs a 5 mm (1/4 inch) crack to be able to crawl inside.
One you’ve sealed the holes, erect a bat house so that next year’s bats have a place to roost. Ideally situate the house facing south or exposed to the full sun. The bats like a clear area to fly into so avoid decks, shrubs, or tree foliage in a three meter area around the bat house. If you are using a pole, put up a house on two sides so the bats get a choice of temperatures. Sealing up or destroying a maternal colony can spell disaster to a local bat population so anyone in this situation is asked to contact wildlife authorities to get advice on erecting an alternate structure. Click these links to see instructions on how to build a bat house:
Single Chamber Bat House Plan (PDF)
Large Bat House Suitable to Replace Maternal Colony Habitat (PDF)
Go to Bat Conservation International for bat house plans and more tips on attracting bats. Avoid handling bats. Of bats found sick and brought in for testing in BC about 5 % have rabies. Estimates are that less than .01 % of all wild bats carry rabies but people should always be cautious.
Bat facts
- There are almost 1200 species of bats, that’s one quarter of all mammal species.
- Bats have many important ecological functions worldwide: pollinating flowers, dispersing seeds, and here in North America—keeping insect population in check. They are a major predator of some agricultural insect pests.
- Bats emit sounds that echo off surrounding objects and return to their large ears. Echolocation allows them to target flying insects which they usually scoop up with inside their tail membranes.
- The large Yuma bat colony in downtown Peachland has its own web site and bat camera at http://www.peachlandbats.ca/
- Wind farms can kill bats affected by the air pressure of the windmills.
- White Nose syndrome is a fungus that is affecting bats in cave hibernation sites in eastern North America. It can kill of the whole population of a cave. Cave spelunkers are asked to clean their gear to stop the spread of the fungal disease.
For more information on bats view our Spotlight on Bats of the South Okanagan Similkameen section.