People are finally recognizing the value of bats. Maligned for millennia out of fear that they are dirty and diseased, even blood-sucking vampires, bats have faced widespread extermination. While some tropical bats do feed on blood, and rabies is a genuine concern, the advantages of having these creatures around far outweigh the small health hazards they pose. As pollinators of flowers and distributors of seeds, they play an important ecological role. As predators of insects, they benefit us by devouring pests. All bats native to Canada are insectivores. They typically consume about half their weight in insects each night, preferring moths, beetles, mayflies, midges, and mosquitoes (the closest thing to vampires among us).
Along with our growing respect for bats comes awareness that their populations are plummeting or — in the case of Keen's, fringed, spotted, and pallid bats — at risk of extinction in Canada. Pesticides absorbed from the insects that bats eat are a key threat. Colonial species, such as yuma, little brown, and pipistrelle bats, face a chronic lack of summer roosts (tree cavities, abandoned buildings, and crevices in rocks). These short- distance migrants find a similar shortage during their search for winter roosts (cellars, tunnels, caves, and old mine shafts) in which to hibernate. Solitary species, such as hoary, red, and silver-haired bats, are long-distance migrants with different roosting needs (leafy hardwood trees in summer, hollow trees down south in winter). Our efforts to conserve and create bat habitat will allow these mammalian marvels to continue as some of nature's most valuable creatures.
Turn Your Schoolyard into a Bat Magnet
Move over, birds and butterflies. Bats appreciate gardens too — not so much for their blooms as for the delectable bugs they attract.
- To turn your schoolyard into a bat magnet, start by enticing night-flying insects with plants that bloom both day and night. Choose bittercress, four-o'clock, fireweed, goldenrod, phlox, wild sweet-William, bachelor's-buttons, and cardinal flower, as well as aromatic herbs like lavender, spearmint, thyme, and sage. Arrange plantings in clumps to concentrate food sources. For biointensive gardening tips, see "A Square Yard in Your Schoolyard".
- Install a bat light in your schoolyard. Leave it on at dusk to encourage moths and other night-flying insects and, consequently, foraging bats. Mercury vapour lights are particularly alluring to insects.
- Build a shallow pond that appeals to mayflies, caddis-flies, and other insects that start life in freshwater and emerge as adults. Guidelines appear here: “Build a Dragonfly Pond”.
- Avoid using pesticides. They will not only negate your efforts to attract bugs and bats but also harm the very species you want to help.
Trees for Travellers
Whether they’re coming, going, or just hanging out, most bats can’t do without trees.
- Plant leafy deciduous and thick coniferous trees, such as elms, maples, spruces, and pines, for hoary, red, and other foliage-roosting bats.
- Conserve living and dead hollow trees for evening, pallid, big brown, and other cavity-roosting bats.
Bats Meet Birds
Imagine . . . bats and birds living together in one box. Often coexisting in snags and artificial structures, these odd housemates get along remarkably well. Most bats and birds work separate shifts — nocturnal and diurnal — and are not at risk of infecting each other since they carry different parasites. The best way to preserve this happy marriage is to save snags. (These standing dead trees are also home to countless other creatures.) The next best resort is to provide artificial accommodations. Rather than building separate structures, why not meet the needs of both bats and birds in a single structure with different compartments? The following design will lodge big brown, little brown, pipistrelle, and other colonial bats, plus such migratory birds as tree swallows and great-crested flycatchers. With modifications in the size of the entrance hole and dimensions of the box, it will house other cavity-nesting birds, from wood ducks to woodpeckers.
- Use 2-cm (3/4") softwood lumber, such as cedar or pine. Do not use pressure-treated wood. It can be toxic to young bats and birds.
- Cut the front, sides, floor, roof, back, and partitions (see diagram).
- Bore an entrance hole in the front panel (4 cm in diameter for bluebirds and tree swallows, 5 cm for great-crested flycatchers) 4 cm from the top.
- Drill small drainage holes on the side panels, just above the floor.
- Saw shallow, horizontal grooves (2 mm deep and 1 cm apart) on the inner surfaces of the bat section, including walls and roost partitions, to enable bats to crawl inside.
- Assemble the pieces as in the construction plan, using 4-cm (2") coated flat-head screws and bond-fast glue. The openings between the roost partitions should be 2 to 2.5 cm wide
- Paint the outside of the structure dark brown or grey.
- In early April, choose a site near a lake, pond, marsh, stream, or river with plenty of insects, ideally inhabited by the species you hope to attract.
- Hang the box 3 to 5 m off the ground on a tree- trunk or, preferably, the side of a building that faces east or southeast and catches the morning sun. The spot should be sheltered from the wind and at least 6 m from neighbouring trees. To prevent house sparrows and European starlings from moving in, leave the entrance to the upper compartment covered until bird migrants appear in spring.
- Have patience. Your structure may remain vacant for a year or two, but its dual purpose doubles the chances that bats and birds will eventually move in.
- Clean the box each fall and ensure that it stays in good repair.
Improve Your Batting Average
Here are some strategies that will increase your chances of keeping bats in belfries — and other habitats — in your area:
- Learn more about bats. Do a classroom project on these fascinating mammals. You'll find an abundance of information on Canada's 19 species of bats in your library and on the internet.
- Whether they're coming, going, or just hanging out, most bats can't do without trees. Plant leafy deciduous and thick coniferous trees, such as elms, maples, spruces, and pines, for hoary, red, and other foliage-roosting bats.
- Conserve living and dead hollow trees for evening, pallid, big brown, and other cavity- roosting bats.
- Create positive public relations for bats by exploding old myths and misunderstandings and informing your family and friends about their ecological importance and the threats they're up against.
- Urge others to stay out of caves and old mine shafts without permission from conservation authorities. Such disruptions can seriously harm, or even kill, nursing and hibernating bats and bring people too close to potentially rabid animals.
- Contact Bat Conservation International (BCI) for additional projects, such as guidelines for turning bridges and culverts into ideal bat abodes. E-mail firstname.lastname@example.org, or visit www.batcon.org.
Hot Under the Collar
Much to the surprise of wildlife biologists, sheet metal collars wrapped around trees not only protect nesting birds from predators but also create ideal roosts for bats. Corrugated metal, loosely fitted, allows bats that normally roost under bark to regulate their temperatures by crawling around a tree to the sunny or shady side. Unlike loose bark, these metal collars can be placed where needed and last for years. They should be at least a metre wide, secured along the seam with aluminum nails, and have enough space underneath (two or three centimetres wide) that bats can enter and move around.
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