Recognizing our Canadian bats References Build a bat roosting box Bats and how to attract them to your yard BATS, ALTHOUGH OFTEN MALIGNED, are actually an important ally for gardeners. They are the primary predators of night-flying insects, including moths, beetles, and mosquitoes. By controlling these insect populations, bats help keep garden pests, such as cutworms or corn earworms, under control. All bats in Canada are insectivorous, meaning they eat insects. They are very efficient hunters — most consume up to 50% of their body weight in insects each night. Little brown bats, the most common bat in Canada, can catch hundreds of mosquitoes in just one hour. Many insects have developed the ability to hear bats even at great distances so that the mere presence of bats in an area will vanquish insect pests. Bats are proficient hunters because of their prowess at using echolocation. They send out pulses of sound which echo off objects allowing them to locate and identify their prey. Their skill, in both echolocation and manoeuvrability, is such that they can rapidly detect and avoid even the most delicate of obstacles. (The myth that bats get caught in people's hair is just that — a myth.) Bats are attracted to an area if it meets their need for food, water, and shelter. The presence of a fairly large source of fresh water, especially a stream, river, or lake, is one of the key indicators of good bat habitat. These areas provide not only fresh water, but also excellent hunting grounds for insects. A number of bat species in the Ottawa area are known to use bat houses, in particular the little brown bat and big brown bat. The success of a bat house in attracting bat inhabitants is dependent on a number of factors: Proper spacing of the roosting cavity — 3/4" Houses should be painted a dark colour for greater warmth Proper caulking prevents drafts (however, ventilation slots are important) Maximum sun exposure (houses placed on trees often do not receive sufficient sunshine) Protect bats by ensuring there are no nearby limbs that allow easy access for predators. The sides of houses or tall poles provide the best protection Bat houses should be 5–10 metres from the ground Do not place bat houses near bright lights (some bats even fear to venture out on nights with a full moon) Even the most spectacular, well-placed house will not attract bats if it is in an area that fails to provide them with food and water. If you know there are bats in your area and have provided a well-constructed bat house and yet have no bat tenants for 2 years, try moving the house to a new spot — especially one with more sun. If, despite all efforts, the house remains empty it may be that bats in your area have all the roosts they require. Bats should be considered an important visitor to any garden. Whether you actively encourage them to make your yard their home, or simply leave them to live in peace, they will reward you with their wonderful ability to purge your garden of insect pests. RECOGNIZING OUR CANADIAN BATS In Canada, 18 species of bats have been identified; eight within 50 km of Parliament Hill. Because they fly at twilight, or in the dark, bats are extremely difficult to identify by sight. Sound-recording equipment is reliable for identifying only three local species, all of which are rare or uncommon. Size can be a determinant but most experts prefer to examine them in the hand for positive identification. All bats are medium to dark brown in colour. Local species range from the Little Brown Bat with a forearm size of 38 mm to the Hoary Bat with a forearm over 51 mm. The following species are found in our region. An asterisk marks the ones that migrate. Eastern Small-footed Bat (Myotis leibii) rare Little Brown Bat (Myotis lucifuga) common Northern Long-eared Bat (Myotis septentrionalis) uncommon Silver-haired Bat* (Lasionycteris noctivagans) uncommon Northern Pipistrelle (Pipistrellus sublavus) rare Big Brown Bat (Eptesicus fuscus) very common Eastern Red Bat* (Lasiurus borealis) rare Hoary Bat* (Lasiurus cinereus) uncommon REFERENCES Bat Conservation International web site. Canadian Wildlife Federation's Wild about gardeing web site: Bats Canadian Wildlife Service, Hinterland Who's Who. Bats Dobbyn, J. 1994. Atlas of the mammals of Ontario. Federation of Ontario Naturalists, Toronto. Rand, A.L. 1945. Mammals of the Ottawa district. Canadian Field-Naturalist, 59(4), 111-132. BUILD A BAT ROOSTING BOX LUMBER REQUIRED 1" x 8" x 15¾" — 5 pieces (2 for front, 3 for back) 1" x 4" x 15¾" — 1 piece for front 1" x 4" x 16½" — 1 piece for top 1" x 1" x 12¾" — 1 piece for entry restriction 2" x 2" x 21¾" — 2 pieces for sides 2" x 2" x 12¾" — 1 piece for ceiling Piece of nylon screening, 19¾" long x 14¼" wide. Fold sides and top over ¾". Note: The dimensions shown on the diagram are trimmed sizes, e.g., a 1" x 4" piece of lumber is acutally ¾" x 3½". This page was revised on 13 February 2007 © Fletcher Wildlife Garden Text: Maria MacRae and Jeff Harrison Photo: Richard Van Vleck Our e-mail address