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By Heather Polowyk, Aerial Insectivore Conservation Biologist
Just as human homes vary from high density, compacted highrises, to sprawling country bungalows, birds have developed unique ways to house their young. Nests are an essential part of the breeding bird story, and in Canada, we are lucky to witness the creativity that goes into them each summer. From extreme differences in size and effort, to some of the most innovative designs, bird nests continue to fascinate ornithologists, birders, and nature lovers everywhere. Peek inside the world of avian innovation, where each nest tells a story of survival, creativity, and instinct.
Following fairy tales like Goldilocks and the Three Bears, these two birds highlight the importance of getting the size just right.
Biggest Nest: Bald Eagle
Bald Eagle nest. Photo: Birds Canada
It is likely no surprise that the biggest nest in Canada belongs to one of the biggest birds, the Bald Eagle. The average Bald eagle nest has a diameter between 1.5 to 1.8 meters and is 0.6 to 1.2 meters tall— roughly the size of a standard refrigerator tipped on its side and rounded off. These conspicuous nests only make sense for a bird at the top of the food chain. Both the males and females work to build the nest, knitting together sticks, moss, grasses and other plant materials. To keep the young warm and comfy, they line the nest with green plant material, lichens and feathers. Despite the huge size, the female usually lays only two eggs. However, nestlings remain in the nest between 8 to 14 weeks, so the extra space is needed for these growing birds. To compare, most smaller song birds spend about a month total in their nest.
Where they are found
Across the boreal forest, Great Lakes and along coastlines, Bald eagles nest in trees, often near large bodies of water, or on the ground along cliff edges if trees are not available. The nest tree type varies depending on what is dominant in the forest, with both coniferous and deciduous trees used.
They usually nest at least 500 m away from human-developed areas, but as humans and Bald Eagles have learned to live in harmony, they will nest closer to human activity.
Bald Eagle. Photo: Birds Canada
Smallest Nest: Calliope Hummingbird
Calliope Hummingbird nest. Inaturalist open source- User: enspring. Taken in BC.
On the other end of the size scale, we have the Calliope Hummingbird, the smallest bird species in Canada, and they have a teeny nest to match. These tiny birds weigh slightly more than a penny (a mere 3 grams!) and their nest has an average outside diameter of 4.3 cm and has a height of 2.5 cm. The inside diameter is only 2 cm and 1.5 cm deep. Unlike the Bald Eagle, the Calliope Hummingbird has predators and needs to hide their nest. They build their nests often on a dead pine cone base, camouflaging the nest as a cone using lichens, barks and mosses. These tiny nests house two eggs that are average 12 by 8 millimeters in size. The chicks remain in the nest between 18 to 21 days.
Where they are found
If you live along the southern British Columbia – Alberta border, you may find a Calliope Hummingbird nest in trees such as Lodgepole pine, Douglas-fir, alder, and apple, along a steep riverbank.
These nests are difficult to find not only because of their tiny size, but because they are on top of a branch, and the outside blends perfectly into the tree.
The best way to find one is to watch the adults and follow them.
Calliope Hummingbird nest. Inaturalist open source- user: leannestacy. Kootenay BC.
These creative birds are for the home renovation fans. Seemingly influenced by interior designers, these two birds have taken the concepts of maximalist and minimalist design to the extreme.
Maximalist style: Black-billed Magpie
Black-billed Magpies are maximalist nest builders. They build dome-shaped nests using large, often thorny sticks.
The dome, which acts like a roof over the nest, has an average height of 75 cm and a width of 50 cm, though each nest varies depending on the individual making it. Males focus on building the dome, while the females focus on making the mud cup and nest lining.
Despite this large dome, it is rather deceiving, as the mud cup, where the eggs are laid, is much smaller. The mud cup has an average of 17 cm diameter. The large dome does serve a purpose though, providing insulation, reducing the energy needed to incubate the eggs.
Black-billed Magpie nest. Inaturalist, Elleneiriksson. CC-BY copyright https://www.inaturalist.org/observations/277064427
Where they are found
Black-billed Magpies are not picky when it comes to finding a place to build their dome nests. Their nests can be found in suburban areas, rural farm fields, open meadows, river banks, or in woodlands. They build their nests in shrubs, trees, and on human structures like utility poles.
Black-billed Magpie. Photo: Kwok Wai
Minimalist style: Common Poorwill
Common Poorwill prefer the less is more concept when nesting. Often covered by shrubs, on various groundcover including leaf litter, gravel or bare ground, the females make a small scrape to lay her eggs. The eggs are often white, and can stand out.
Thankfully, the female and male, who both incubate the eggs, are experts in camouflage and bravery. When a threat is nearby, they remain in the nest until the predator is less than 2 m away.
Once flushed, or scared away, from the nest, they will hiss, growl and attempt a distraction display to move the predator from the nest and towards them.
Common Poorwill nest. Inaturalist, User: margaretgallagher. CC BY-NC, https://www.inaturalist.org/observations/168222962 – cannot be used for commercial purposes.
Where they are found
You can find Common Poorwills in Southern British Columbia, southeastern Alberta, and southwestern Saskatchewan. Common Poorwills are often easy to hear but difficult to see. They are most active at dusk and dawn, spending the night foraging. They prefer open, arid, and shrubby habitats. The adults are super camouflage experts, keeping the nest well hidden.
Common Poorwill. Photo: Alan Burger.
Artists of the bird world. When viewing these nests, it is easy to draw comparisons to artistic movements like surrealism, impressionism and avant-garde. Surrealism is characterized by juxtaposing ideas often in ways that seem impossible. Impressionism is all about showing movement. Lastly, avant-garde style is represented by the unusual and experimental. These artistic styles are defined by taking certain concepts to an extreme to produce something beautiful. These birds understood the assignment.
Surrealism: Cliff Swallow
Cliff Swallow nests. Photo: Yousif Attia
The Cliff Swallow is a great example of juxtaposition. Often found attached to 90 degree hard concrete or brick structures, such as under bridges or on the sides of houses, Cliff Swallows build their gourd-shaped nests out of mud. Both males and females build the nest, collecting one mud pellet in each of their bills, they shake their bills to disperse the mud and slowly build up the nest. The average nest is made from between 900 to 1,200 mud pellets and can take up to 18 days to build. The mud walls provide insulation for the eggs from wind and rain. With all the hard work put into building, Cliff Swallows will happily, with some refurbishing, reuse their nest the following breeding season.
Where they are found
Find these birds and their nests from Nova Scotia to British Columbia and Northwest Territories and Yukon.
Cliff Swallows nest in colonies making them easier to find. Look for them under bridges, and along the sides of buildings.
They are very active during the day, swooping high in the sky as they forage on flying insects.
Cliff Swallow. Photo: Nick Saunders
Impressionist: Baltimore Oriole
Baltimore Oriole nest. Open source from INaturalist. User- Loarie.
Baltimore Oriole embrace the concept of movement by weaving 8 to 10 cm basket nests that hang from a forked-branch in the upper part of a tree. These intricate, sock-like nests are made in three stages, utilizing specific materials during each stage. First, the outside is built with flexible fibres, like grasses and bark. Next, the inner part is woven out of fibres that help maintain the gourd-like shape. Finally, the nest lining is made from soft, cozy fibres such as feathers. The female is the nest builder, weaving the fibres together by poking her bill randomly, creating a tangle of fibres.
Where they are found
From Nova Scotia to Alberta, find Baltimore Oriole nests hanging high up in deciduous trees. They look for open wooded habitats, like forest edges or small patches of trees.
Places like backyards, and local parks are the perfect place to look.
Baltimore Oriole. Photo: Stephane Picard
Avant-garde: Ovenbird
Ovenbird nest. Photo: Jody Allair
Ovenbirds get their unusual name from their unusual nest style. They place their nest on the ground where leaf litter is present. The female clears a spot on the ground, lining the edge of the clearing with bark, small sticks and grasses. Using dead leaves as the main material, the female builds a dome with a nest cup inside and a side entrance. The dome and cup are built together into one unit, appearing to us like an oven. Ovenbird nests are super well camouflaged thanks to the dead leaves and the placement near small trees or shrubs.
Where they are found
From Newfoundland to Yukon, find Ovenbirds in forests with deciduous trees. Start by listening for their explosive, repetitive, “TEACHER, TEACHER, TEACHER” call.
Once you know Ovenbirds are present, pay attention to the ground, watching for Ovenbirds appearing from the leaf litter.
These nests are very difficult to see, use extra caution when searching to ensure you do not accidently trample the nest.
Ovenbird. Photo: Melanie Howarth
Respect the Nest
As always with wildlife, please ensure the safety of the birds when searching for their nests. Use binoculars to look quietly from a safe distance. Listen for alarm calls and move away from the area if you hear them. Move along quickly to allow for the parents to return to incubating eggs or feeding young. If you find a nest, do not leave a dead end path. Instead, continue a path beyond the nest to disperse your scent for sniffing predators. Never touch a nest, eggs or nestlings.
If you find a nest, report your sightings to Project NestWatch. Visit https://www.birdscanada.org/bird-science/project-nestwatch to learn more.