Integrated Pest Management Guide

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BATS AND BIRDS

BATS

Bats are flying mammals that are primarily nocturnal. Bats sleep during the day, and hunt and feed at night. They have teeth and a body covering of fur. They give birth once a year, in mid June, to live young and nurse them with milk.

Because bats of Canada feed on insects, they are beneficial to agriculture and the environment. British Columbia has 17 species of bats, more than any other part of Canada. Some of our bats avoid winter by migrating elsewhere; others hibernate in caves or old mines. The little brown bat (Myotis lucifugus) is the most common Canadian bat and the hoary bat (Lasiurus cinereus) is the largest Canadian species.

Little is known about the local bat species of the Vancouver area. Approximately seven species, including the little brown bat (Myotis lucifugus), Townsend's big-eared bat (Plecotus townsendii), and Yuma bat (Myotis yumanensis) make their homes under the bark of trees in Stanley Park.

Bats usually catch insects like moths, mosquitoes, beetles, mayflies, caddis flies, and midges in flight. Insectivorous species of bats typically consume 30 - 50% of their body weight in insects each night. Birds that pursue flying insects often catch prey in their mouth, but most insectivorous bats scoop up their victims in wing or tail membranes before transferring them to their mouth.


Bat

In the summer, female little brown bats aggregate in colonies that often are located in the attics of buildings. Several hundred of these bats may inhabit one colony, moving into it in April or May. The months of July and August are spent in heavy feeding, as the females and young build up their fat reserves for hibernation. Little brown bats live for up to 10 years. In the fall, when weather conditions become harsher and the food supply of insects disappears, Canadian bats hibernate. Bats in Canada may be divided into two groups based on their seasonal movements. Some common species, including the building roosting ones, travel from a few kilometers to several hundred kilometers between summer quarters and winter ones where they often hibernate in caves. Other species, such as the tree-roosting bats, migrate to more southern locations where they may hibernate in hollow trees or remain active.

"Echolocation is an active mode of orientation in which the bat emits pulses of sound and listens for the returning echoes using its large ears. The difference between the original sound and its echo contains the information used by the bat to locate and identify objects in its path. The ears of many insects, such as moths, lacewings, crickets, and some mantids, are sensitive to the echolocation calls of bats. These insects thus receive warning of a bat's approach and are able to evade capture. Again, the Spotted Bat is an interesting exception. Its lower frequency echolocation calls are not detected by most insects, so the insects are less likely to flee" (Canadian Wildlife Service Hinterland Who's Who series (Web site)).

HOW TO ATTRACT BATS

Some bat species are gregarious. Whole colonies will roost and breed in caves, hollow trees, and attics. It is much easier to attract bats to temporary roosting boxes than it is to get them to breed. The bats most attracted to roosting boxes are the common species like the little brown and big brown bat and some less common species like Yuma bat and the Pallid bat (Antrozous pallidus). Spring and autumn are bats' favorite times for relocating and the most likely times that bats will find your box.

Boxes are usually placed 5 - 7 meters (15 - 21 feet) above the ground on poles, buildings or tree trunks that are relatively free of branches below the box to provide unobstructed access. It is recommended that the box face south or southeast and have at least 6 hours of direct sun per day. Boxes should be made of soft wood WITHOUT WOOD PRESERVATIVES which may be harmful to bats. The wood should be slightly rough on all surfaces so that bats can land and investigate by crawling over the box. Boxes should also be rain proof.

The best location for attracting a nursery colony of bats is within 400 meters of a pond, lake, or river, with diverse habitat, especially a mixture of farmland and natural vegetation.

Because the boxes cannot provide the stable, relatively warm winter temperature that bats require, bats will not use them to hibernate. Once bats have gone into hibernation, boxes should be taken down, cleaned with a garden hose, and stored.

Large, single-chamber bat houses can also be simply made by using a sheet of 1.25 cm (1/2 inch) thick plywood mounted on wood or masonry structures such as bridges, barns or other buildings with good sun exposure. Bats often roost naturally behind similar structures such as billboard signs or shutters. Ventilation is critical in all houses. For more information on building bat boxes, see the REFERENCES section and visit the internet sites mentioned in the WEB SITES section of this manual.

BIRDS

While birds of prey feed on small mammals like voles, other bird species feed exclusively on insects.

Swallows have been observed flying over cranberry beds catching flying girdler and fireworm moths. Attracting birds to cranberry farms is a natural way to help control these pests. At least two species, the barn swallow (Hirundo rustica) and the tree swallow (Tachycineta bicolor), are regularly seen nesting on farm sites.

HOW TO ATTRACT BIRDS

Waterproof bird houses, also called nest boxes, will provide shelter to nesting birds on your farm. Location of the bird house is very important. Houses should not interfere with the normal maintenance of the beds. They should not be placed within range of sprinkler heads. Nest boxes should be out in the open, which makes it impossible to avoid direct sunlight. In order to prevent dehydration of the young birds inside, drill two 1.25 cm (1/2 inch) holes on either side of the box underneath the roof.

The entrance hole of the box should be the right size for the bird species you want to attract. Undesirable birds like house sparrows or starlings will compete for the same nesting cavity. The inside exit should have a rough surface so that the birds can get a good foothold to exit the box. When the birds have left their houses after nesting, boxes should be cleaned. Removing the nest and nesting material from the floor prevents bird parasites from infesting the next brood.

For more information on building bird houses nest boxes, see the REFERENCES section and visit the internet sites mentioned in the WEB SITES section of this manual.