Providing Wild Creatures with Shelter and Housing
by Myrna Pearman
November 25, 2007

In my first article on wildlife gardening, I outlined the basics of creating backyard wildlife habitat - providing space within which wild creatures can find food, water and shelter. Food and water are topics I will cover in future columns. Through this column on shelter, I hope to inspire you to consider some unique additions to your garden which will be fun to make, and will add both interest and habitat value to your backyard.

Ellis Bird Farm Ltd has plans for the structures described in this column. A complete set of plans includes the following: bluebird nestboxes, purple martin houses, cliff-swallow nest frames, butterfly hibernation houses, bumblebee boxes, orchard mason/leaf cutter bee blocks, and bat boxes. A chart showing nestbox dimensions for all cavity nesters is also included. To order, send $5 and a SASE to Ellis Bird Farm Ltd, Box 5090, Lacombe, AB T4L 1W7.

For wild creatures, shelter means protection from the elements, safe resting spots, safe spots for roosting at night (or, for bats, a safe place to roost during the day), hiding areas from predators, and secure spaces to safely raise young. Shelter is most important, of course, during cold or inclement weather and during the nesting season. It is important to remember that different types of wildlife have different shelter requirements. For an overwintering Mourning Cloak butterfly, for example, home might be a few old logs piled together; for a pair of breeding Tree Swallows, home is a cavity in a tree or a nestbox. Some creatures will find their own denning or nesting sites if you provide them with the right type habitat, while others are more likely to be attracted to "artificial" structures such as nestboxes or other abodes.

In an urban backyard setting, trees and treed areas provide the most important sources of shelter for the widest variety of wildlife. By planting a mixture of coniferous and deciduous trees and shrubs, you will maximize the quality of shelter provided. Retain as many dead and dying trees as possible in your yard; these snags are condos and cafeterias to a wide variety of creatures, from insects to bats and cavity-nesting birds. Its interesting how snags - and other shelters, such as brush piles, rock piles and patches of "wild" take on a whole new sense of beauty and importance when we realize the important role they play in sustaining backyard biodiversity.


It seems that gardeners have long believed that gardens and bugs cannot coexist. Thankfully, this attitude is changing as we realize how critically important insects are in the ecosystem. It behoves us to learn about these creatures, and to do what we can to encourage beneficial species in our yards and gardens.

For the most part, insects will find their own forms of shelter in vegetation, on or in buildings, and under leaf litter. But we can also help them out by providing additional nesting material and substrates. Insects that use mud will be attracted to wet soil (mud-daubing wasps, for example). Likewise, insects that use materials such as sand or twigs will be more likely to nest in your yard if you offer these provisions.

Butterflies which overwinter in the adult form may be attracted to a backyard if suitable hibernation shelter is offered. Such shelter would be provided by leaf mulches, or in crannies in outbuildings, wood or brush piles, garages and even houses. Some species, such as Mourning Cloaks and Milbert’s Tortoiseshells) may also be enticed to use specially designed butterfly hibernation boxes which are set out in sheltered, wooded areas. If possible, keep the house covered with snow for the entire winter.

Deep leaf mulches may also attract butterflies if they are placed under hedgerows or shelterbelts, or in other sheltered areas. Wood or brush piles intended to attract overwintering butterflies should be set in a shady, protected location. Do not disturb the boxes, mulches, piles, etc. until after the adults have re-emerged in the spring.

Bumblebees, which are native social bees and very important pollinators, will sometimes use nestboxes. Bumblebee boxes should be placed near favoured food plants (clover, etc.) but away from where they may be disturbed by humans. Ideal bumblebee box sites are in sheltered locations along the east sides of hedgerows, fence lines, rock piles, shelter belts, etc. The box should be set out in the spring before the leaves are out. It should be dug into the ground to about half its depth, and secured to prevent it from being dug out by skunks. The end of the tube should be flush with the ground surface.

Solitary bees, such as leaf cutter bees and orchard mason bees can be attracted to use 'hives' constructed from small bundles of hollow stemmed plants (e.g. raspberry canes) or pop straws. Hang these bundles in protected locations such as under fence and balcony rails, decks etc. Another way to attract these bees is to construct special bee blocks. The simplest way to construct a bee block is to drill 7-mm (5/16 in.) holes in a block of wood (fir is ideal) and hang it in a visible spot in your garden or yard. A sample is shown here. The holes should be drilled about three inches deep, and should be spaced at X mm (3/4 in.) intervals.


Although most people are not as enthusiastic about attracting herps (short for "herpetozoans", the collective name for amphibians and reptiles) as they are birds to their backyards, these fascinating creatures can add a great deal of interest and diversity to a backyard. The only species of amphibians (salamanders, frogs and toads) or reptiles (turtles, lizards and snakes) you will attract are those which naturally occur in your area, and which can find their basic needs met by the specific backyard habitat which you provide. You are most likely to attract the species that live near water, and are widespread and abundant. Not surprisingly, backyard ponds isolated in the middle of a wide expanse of lawn or in the middle of a city suburb will not be as likely to attract herps as those found in backyards which are near natural areas or tracts of undisturbed habitat.

Amphibians require shelter and cover which offers darkness and dampness while the one shared reptile requirement is the provision of safe sunning spots. Other specific requirements vary according to species. All herps need habitat which offers protection from predators.

The ideal backyard for herps contains a properly constructed pond or water garden which is bordered on at least one side with tall grasses or ferns and to which has been added different types of shelters. Not only do these shelters provide important cover, they provide foraging areas and sunning sites as well. Burrows, rock piles, old boards, wood slabs with the bark still on, large logs (25 cm+) of trees that decompose quickly (e.g. poplar), hollow logs of any size, and brush piles can all be used. You can also make or purchase small pottery pots which can be upturned and used as herp shelters. Be creative! Use only shallow structures, as the interior space needs to be kept humid. They should also be placed under the shade of some overhanging vegetation.

Toads, salamanders and some species of frogs may even use a backyard that does not have a pond as long as the type of shelter, described above, is provided. Salamanders will most likely be attracted to areas of heavy deciduous leaf litter where their main food sources - insects, spiders, slugs and worms - can be found and where the moist microclimate prevents their skin from drying out. If you can leave a patch of ground in the treed of your area unraked, you will be creating excellent salamander habitat (not to mention all the ground-feeding birds you’ll attract as well!).

Drier areas around a pond can be made attractive to reptiles by setting up rock piles or stone walls. A portion of this area should be fully exposed to the sun to provide an essential warming area. The rest of the area should be shaded.


Trees with densely packed branches provide secure hiding, nesting and roosting sites for birds. Conifers offer the most thermal protection during the winter while deciduous trees and shrubs are an important source of shelter during the spring and summer. Temporary coniferous cover can be added to a yard during the winter by setting out old Christmas trees. Snags (described above) also provide important shelter.


Nestboxes provide nesting sites for birds that require a hole, or cavity, in which to nest. Primary cavity-nesting species, such as woodpeckers, are adapted to create their own cavities by excavating holes in tree trunks. Secondary cavity nesters also require cavities for nesting, but because they lack the adaptations necessary for excavating, rely on pre-existing cavities. Because of this ready acceptance of "second-hand housing", most species of secondary cavity-nesting birds will readily accept "artificial" nesting structures such as nestboxes, gourds, etc. In Canada, the most common secondary cavity-nesting birds include chickadees (Black-capped and Boreal), bluebirds (Eastern, Western and Mountain), Tree Swallows and House Wrens. The most common larger cavity nesters include ducks (Wood Duck, Common Goldeneye, Bufflehead), American Kestrels and Saw-whet Owls. In urban areas, the native species most likely to take up residence in a nestbox are Tree Swallows and House Wrens. If you are interested in detailed information about cavity-nesting birds, we suggest you order a copy of our book Nestboxes for Prairie Birds (see part one of this section for ordering information.). Nestbox dimensions for all cavity-nesters is included with the information package, available from Ellis Bird Farm (see introduction).

Unfortunately, the introduced, pesky and destructive House Sparrow is a common urban resident, and is often the first to take up residence in a nestbox. Our book, Nestboxes for Prairie Birds, has a section on how to deal with the problem of House Sparrows.

Whether you are making a nestbox for the tiny wren or the large Common Goldeneye, it is important to make it functional and durable. Don’t make or buy something which is the wrong size or is not safe or secure. There are plenty of excellent styles available for sale in wildlife specialty stores or through nature centres.

The best material for constructing nestboxes is 19-mm (3/4-in.) cedar or exterior grade plywood. Milk cartons, plastic jugs and tin cans are sometimes converted into would-be nestboxes, but these are less than ideal because they do not provide adequate insulation against the extremes of heat and cold. Do not use pressure treated wood.

It is important that a nestbox have the following characteristics:

  • one panel (top, front or side) that opens easily to allow for observation, cleaning and removal of pests;
  • ventilation holes near the top of each side board. Small holes can be drilled on an upward angle to provide ventilation without allowing rain to blow in;
  • adequate drainage. Small holes can be drilled in the floor, or the corners of the floor can be cut off;
  • a roof that slopes towards the front of the box with an overhang extending at least 5 cm (2 in.). The overhang provides shade and protects the entrance hole from driving rains;
  • shallow saw slashes (saw kerfs) on the inside of the front panel to help fledglings exit the box

Perches should not be put on the front of small boxes because they assist House Sparrows and predators to enter.

Since cats are so abundant in urban areas and around acreages, you may want to carefully consider how and to what you mount your nestbox. To reduce the possibility of predation by cats or raccoons, mount your box on free-standing posts (e.g.. galvanized pipe, rebar, U-posts, conduit or PVC pipe). In areas where they occur, raccoons can be excluded by placing metal baffles or pieces of stovepipe below the box. Spreading a thick layer of chassis or white lithium grease, or spraying carnauba wax on the mounting post will also serve as a deterrent.


Where they occur, Cliff Swallows may use modified nestboxes constructed from either wood or wire mesh covered with a mixture of mud and cement. The birds will finish the nest by adding mud to its neck. In the fall, the mud that the birds added should be removed and the cavities cleaned. A stick can be put into each entrance hole to exclude sparrows and starlings. Remove when the swallows arrive back in the spring. These nesting structures should be attached directly below the soffit of a tall outbuilding.


Nesting shelves are attractive to such species as American Robins, Barns Swallows and phoebes. Nesting shelves should have a floor size of about 15 cm x 15 cm (6 x 6 in.) and should be placed under the eaves of buildings. Phoebes are most likely to use a bracket located near water.


If you can’t convince your backyard Barn Swallows to move their nest from above the light fixture above your back door, try using nesting nails to encourage them to "choose" an appropriate nesting site. Nesting nails can be used on the exterior of a residential building, or on both the exterior or interior of an outbuilding. Pound two small spikes, about 2.5 cm (1 in.) apart, into a beam or wall so that they protrude out about 3.8 cm (1.5 in.). The birds will use the nails as support structures for their nest. Cliff Swallows and Robins may also use these structures.


Artificial roosts provide shelter and thermal cover for both overwintering and migrating birds. They are most effective where natural roosts - dense stands of coniferous trees in shelter areas such as ravines - are lacking and where natural features, such as lakes or rivers, attract many migrating birds.

The best locations for artificial roosts are the leeward sides of small groves of trees or near the bottoms of depressions where they will be visible yet sheltered from prevailing winds.

Roosts can be constructed from a frame of lumber, or concrete-reinforcing mesh, stretched across an elevated steel frame. The roost should measure 2.6 m x 5 m (8 x 16 ft.) and 2 m (6 ft.) above the ground. Branches should be piled at least 1 m (3 ft.) high on top of the frame and should be secured with wire or additional mesh.

Artificial roosting boxes can also be constructed. In northern regions, roosting boxes should be constructed with 19-mm (3/4 in.) plywood and lined with polystyrene insulation.


As with birds, most mammals will find their own shelter as long as adequate habitat is provided. Although an urban/acreage backyard is most likely to attract only small mammals, a smaller yard might also encompass the territory of a larger mammal. Rabbits, hares, raccoons, squirrels, chipmunks, woodchucks, foxes, ground squirrels and weasels are the mammals most likely to respond to the provision of backyard habitat.

Although you may welcome these creatures into your yard, they might cause problems should they decide to move under your house, raise their young in an inappropriate spot, or develop an appetite for your neighbour's garden vegetables or favourite house cat. To minimize the potential for conflict, it is usually advisable to encourage mammals to share "the far corner" of the yard.


Rock walls, rockpiles or brush piles will attract a wide variety of animals because they provide nesting sites, denning sites, and shelter from predators and the elements. For brush piles to be useful to wildlife, they should be located near sources of food and other types of cover such as unused fence or field corners, fencerows, hedgerows, clearings, edges of gullies, unused cropland etc. Rock walls and rockpiles are constructed from stones while brush piles can be constructed from branches, old fence posts, stumps or even discarded Christmas trees.

A rockpile should be constructed so that the largest rocks are along the bottom. These base rocks should be 20 cm to 30 cm (7 - 8 in.) in diameter. Smaller rocks can then be placed on top.

Brush piles should be constructed so that the thickest and largest materials form the foundation while smaller branches or other material is piled on top. Conifer boughs can be placed on top to provide additional protection.

The wildlife value of your rock wall, rockpile or brushpile can be greatly enhanced if adequate internal spaces are included to provide denning sites and tunnels. This can be achieved by the strategic placement of rocks or branches, or by placing 15-cm (6-in.) PVC pipe, flex hose, weeping tile or sections of hollow logs within the structure. To construct tunnels, lay the tunnel material in a zig zag fashion. Make sure that the entrance and exit holes won’t collapse. Burrows can be provided by laying the material in at a 45o angle. One end of the tunnel pipe is at the edge of the brushpile while the other is buried into the material. Don’t use PVC pipe or other slippery materials.

A central nesting structure can also be incorporated by using an overturned bucket with at least 4 "spokes" of 12.7-cm or 15-cm (5- or 6-in.) pipes radiating out from the bucket to the edge of the mound.


Bat houses are becoming all the rage across North America. And they work! Setting out a bat house in your yard will not only help with biological mosquito control, it will likely stimulate lots of interest and discussion!

Although relatively little research has been done on bat houses in Canada, there are several factors crucial to their success. These include: the distances to drinking and feeding areas; the daily temperature profile (determined by house size, shape, insulation and placement); the size and shape of internal roosting spaces; and the roughness of the surfaces to which the bats must cling.

According to a recent survey conducted by Bat Conservation International (BCI), bat houses are most likely to be successful if they are located .5 km (.25 mi) or less from a water source (lake, pond, stream or river) and if they receive six or more hours of sun each day.

Bat boxes should have long roosting chambers, which allows more bats to cluster near the ceiling where they can trap body heat. If the exterior is darkened, the front chambers will readily absorb heat while the rear chambers remain slightly cooler. This is why the Bat Conservation Society of Canada (BCSC) recommends that you stain or paint your bat boxes black or cover them with tar paper or black shingles. They also advise against using wood that has been chemically treated.

Bat boxes should be located a minimum of 4 m (12 ft.) above the ground. The ideal height is about 5 m (20 ft.). Boxes can be mounted on poles, on the sides of buildings or on trees, with trees being the least-preferred.

All inner surfaces of the house must be rough or horizontally grooved so that bats can get a firm foothold. This can be accomplished by etching the back board and roosting partitions with saw kerfs (every 1.27 cm [.5 in.]), or by covering them with fibreglass insect screening cloth or quarter-inch hardware cloth. Metal mesh is too abrasive, and should not be used.

If you would like more information about bats, contact the Bat Conservation Society of Canada, Box 56042, Airways Postal Outlet, Calgary, AB T2E 8K5. Phone: (403) 860-BATS.


Mice, especially Deer Mice, will nest in nestboxes that are located low to the ground and adjacent to high grass or dense shrubbery. Mice boxes should have a second exit at one of the top rear corners. Precautions should be taken around mice (especially Deer Mice), as they may transmit the deadly Hantavirus.

Rabbits can be attracted to underground burrows while hares will look for a suitable location to construct a form, which is a covered depression. Rabbit burrows, constructed from rough untreated wood, should measure about 50 cm x 50 cm (24 x 24 in.) and should be approximately 25 cm (12 in.) deep. Concrete drain pipe or flex hose can be used for entrance tunnels. The box should have a lid but no floor, and should be buried in an area with adequate drainage. The lid can be covered with rocks, brush, soil etc. Occupancy of these burrows will be increased if they are placed adjacent to hedgerow.

Where they occur, raccoons are common night-time visitors in urban areas, especially if a water source is nearby. During the day, they will roost in old buildings, hollow logs or trees, thick vegetation or even old crow nests. Although their propensity for being a nuisance makes them among the less favoured backyard creatures, roosting boxes can be set out for them. The box should have a floor area of 45 cm x 45 cm (18 x 18 in.), should be about 66 cm (26 in.) deep. The entrance hole should be about 20 cm (8 in.) in diameter.

Squirrels will use nestboxes for both nesting and for food storage. They are attracted to boxes that are located in wooded areas, especially those that are attached to trees. They will use boxes ranging in size from a bluebird box to a large merganser duck box. If constructing a box especially for squirrels, use a standard bluebird box design and make the entrance holes at least 41 mm (1 5/8 in.). Squirrels will chew around entrance holes, especially if they are too small for their liking.

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