Cavity-Nesting Birds in Canada — A Complete Species Guide
Canada is home to dozens of bird species that naturally nest in tree cavities and will readily adopt a well-placed nest box. These cavity-nesting birds range from tiny wrens weighing less than 10 grams to large owls spanning nearly a metre in wingspan, and each species has specific requirements for the size, shape, and location of its nesting cavity. Understanding which birds are present in your region of Canada and what they need is the foundation of successful birdhouse gardening. At BIRDHOUSES.ca, we walk you through the most important Canadian cavity nesters and exactly how to attract them.
1. Bluebirds — Eastern, Western & Mountain
Canada's three bluebird species are among the most beloved and sought-after backyard birds on the continent, and all three are strong users of nest boxes. The Eastern Bluebird is found across southern Ontario, Quebec, and the Maritime provinces, nesting in open country with scattered trees and short grass. After suffering dramatic population declines in the mid-20th century due to competition from introduced House Sparrows and European Starlings, the Eastern Bluebird has recovered significantly across much of its Canadian range thanks to the widespread deployment of nest box trails.
The Mountain Bluebird is the species of open grasslands and shrub-steppe across the BC interior, Alberta, Saskatchewan, and Manitoba, nesting in fence posts, old woodpecker holes, and nest boxes in some of the most spectacular landscapes in Canada. The Western Bluebird is a locally distributed species in the southern interior of British Columbia. All three species use the same nest box dimensions — a 1.5-inch entrance hole and a 5×5-inch floor — and respond well to boxes placed on metal baffled poles in open habitat away from woodland edges.
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No bird is more universally present in Canadian backyards than the Black-capped Chickadee, found from the Yukon to Newfoundland in virtually every habitat that contains trees. Chickadees are natural cavity excavators that chip away at soft or rotting wood to create their own nest holes, but they also readily adopt nest boxes filled with wood shavings that give them the excavating experience they instinctively seek. The Mountain Chickadee, found in coniferous forests from BC through Alberta and into southwestern Saskatchewan, uses the same box dimensions.
In the boreal forests and northern woodlands of Canada, the Boreal Chickadee is the resident species, distinguished from the Black-capped by its brown cap and rusty flanks. The Chestnut-backed Chickadee, with its vivid chestnut back and flanks, is the species of the Pacific Coast from southern BC northward. All chickadees use a 1.125-inch entrance hole and a 4×4-inch floor, and all prefer boxes placed at moderate heights in areas with some tree cover rather than fully open locations.
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Shop by Bird Species3. Swallows — Tree Swallows & Purple Martins
The Tree Swallow is arguably the easiest Canadian bird to attract with a nest box — it is aggressive, adaptable, and present across virtually all of Canada during the breeding season. Tree Swallows use a 1.5-inch entrance hole and a 5×5-inch floor, and they prefer boxes mounted on smooth metal poles with baffles over open ground or water. Because they are highly territorial and will not tolerate another Tree Swallow pair nesting within 15 feet, pairs of boxes placed 15 to 20 feet apart (the "double bluebird box" method) are the most effective way to host multiple pairs.
The Purple Martin is North America's largest swallow and one of the most charismatic colonial nesters in Canada. East of the Rockies, Purple Martins are almost entirely dependent on human-provided housing — multi-compartment martin houses and gourd racks mounted on tall poles in open areas near water. Martin colonies require a long-term commitment from the landlord: boxes must be monitored weekly during the nesting season, House Sparrow nests removed promptly, and predator guards maintained. In return, a successful martin colony provides months of spectacular aerial acrobatics and constant, cheerful song throughout the Canadian summer.
4. Woodpeckers — Natural Cavity Creators
Woodpeckers are the original cavity architects of Canadian forests — virtually every cavity used by other nesting birds was either excavated by a woodpecker or expanded from a woodpecker hole by erosion. Several woodpecker species also use nest boxes directly. The Downy Woodpecker, Canada's smallest woodpecker and a year-round resident across most of the country, will use a box with a 1.25-inch entrance hole packed with wood shavings mounted 6 to 20 feet high on a tree or post.
The Northern Flicker, one of Canada's largest and most widespread woodpeckers, is a strong nest box user when natural cavities are in short supply. Flicker boxes are substantial structures — a 2.5-inch entrance hole, a 7×7-inch floor, and a depth of 16 to 18 inches, packed with several inches of wood shavings — and are ideally mounted 6 to 20 feet high on a tree trunk or sturdy post. The Pileated Woodpecker, the crow-sized giant of Canadian forests, occasionally uses very large nest boxes but generally prefers to excavate its own cavities in large-diameter dead trees in mature forest.
5. Owls, Ducks & Other Cavity Nesters
Beyond songbirds and woodpeckers, several other remarkable Canadian species use nest boxes enthusiastically. The Eastern Screech-Owl and Northern Saw-whet Owl are the most commonly box-nesting owls in Canada, using boxes mounted at moderate heights in mature woodland. The Barred Owl will use very large boxes in mature forests with large trees, and the Common Barn Owl, a rare and declining species in southern Ontario and BC, is the subject of active nest box programs in agricultural areas.
Several duck species are also enthusiastic nest box users. The Wood Duck is perhaps the greatest cavity-nesting conservation success story in North America — after near-extinction in the early 20th century, Wood Duck populations have rebounded dramatically thanks largely to the widespread deployment of nest boxes on lakes, rivers, and wetlands across Canada. A Wood Duck box requires a 4×3-inch oval entrance hole, a 10×10-inch floor, and mounting over or near water. The Common Goldeneye and Common Merganser also use large nest boxes mounted near boreal lakes and rivers, as do Common and Hooded Mergansers in appropriate habitat across Canada.