Spring is upon us, and for most birders and naturalists in North America that means one very special thing: Nesting season has arrived! Wildflowers are blooming, trees are leafing out and mammals are raising young as well, making this one of the most exciting and beautiful seasons for nature study.
And if there is one nature find that brings delight to young and old alike, it is the discovery of a bird nest!
Bird nests are endlessly fascinating creations, varying widely in size, shape, style, placement and construction materials. Some birds weave elaborate structures, while others build very little in the way of a nest at all. Coming across nests while exploring nature is one of the most rewarding discoveries, and it is an immense privilege to watch the progress of a nest, from its construction, to egg-laying and incubation, all the way through to the hatching and fledging of young.
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Great-horned Owl on a stick nest.
Great-horned Owls don't build their own nests, but refurbish nests that were built in previous years by hawks or corvids (like ravens).
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If you discover an active bird nest, please keep in mind these rules of etiquette:
-To minimize disturbance to nesting birds, keep visits to the nest short and quiet. Approach quietly, take a quick peek, and leave promptly, staying no longer than a minute.
-To avoid leading predators to the nest, leave the nest by a different path than was used to approach it.
-Visit nests in the afternoon, when the weather is warm. If possible, wait until the female has left the nest before making your visit.
-Don't visit nests during cold or rainy weather, or after dark, in order to avoid flushing the parent from the nest, which leaves chicks vulnerable to cold and predators.
-Don't visit too often: once or twice a week is enough. Visiting every day increases the likelihood that predators will be alerted to the presence of the nest. A nest's best defense is concealment.
-Avoid visiting nests when young are close to fledging, as this could cause the young to leave the nest too soon, making them extra-vulnerable.
-Never touch or otherwise disturb the nest, eggs or birds. Look only!
*If you find a baby bird out of the nest:
The only exception to the "no touching" rule is if you find a nestling without feathers that has obviously fallen out of its nest; in this case, pick it up and put it back in the nest immediately, then leave the area and allow the parent birds to take over caring for their chick(s). If the bird out of the nest is not fully grown but has feathers, it is a fledgling and it is okay for it to be out of the nest; the parents are likely nearby, still caring for their young. You may move the fledgling out of the way of immediate danger if the bird is in the road or the direct path of a cat or dog; otherwise, leave it alone. It's usually best to let nature take its course.
Types of Nests
Most species of waterfowl (ducks and geese) nest on the ground, building open cups of vegetation lined with feathers. But some species of ducks, like Wood Ducks and Bufflehead, are actually cavity nesters (see below)! While ducks and geese tend to nest near water, grebes and loons nest on the water, building floating platforms of vegetation on which to lay their eggs.
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| The waterside ground nest of a Canada Goose. |
Shorebirds also nest on the ground, building shallow nests of plant material in which to lay their well-camouflaged eggs. Some groups of shorebirds, as well gulls and terns, build nests that are called "scrapes," which are exactly what they sound like: little more than shallow depressions in rocky or sandy substrate in which to lay their eggs. These eggs are exquisitely designed to match their environment perfectly, but they are still vulnerable to crushing in areas with high human (and canine) foot traffic, like popular beaches.
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| A Killdeer and its well-camouflaged scrape nest on the ground. |
Cliffside nests are the specialty of many sea birds, such as cormorants, murres, gannets, guillemots and kittiwakes, which all nest in large, gregarious cliffside colonies. Some species of raptors, like Peregrine Falcons and Rough-legged Hawks, nest on remote cliffs as well.
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| A breeding colony of Brandt's Cormorants, towards the end of the nesting season (note the quite flattened nests and grown young!) |
Stick nests are a popular choice for a number of larger birds, like raptors, corvids and wading birds. Some wading birds, like Great Blue Herons and Great Egrets, nest colonially in large breeding colonies called heronries, while others, like the secretive Green Heron, nest singly.
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| The stick nests of a heronry, with nesting Great Blue Herons and Great Egrets. |
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| A secretive Green Heron on its well-hidden stick nest |
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| A Red-tailed Hawk on its stick nest (sometimes called a platform nest) |
Doves build notoriously flimsy nests, often perched precariously on branches or ledges on manmade structures. It's not unusual to find a dove nest in a hanging planter, tucked under the eaves, or wedged into other convenient little nooks around the house. You might even consider putting out a
nesting platform, designed especially for doves.
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| Mourning Dove with her nearly-fledged young on their rather precarious nest of grass and twigs. |
Probably the most familiar and "traditional" style of bird nest is the simple cup nest constructed by many of our species of songbirds. Warblers, sparrows, finches, vireos, thrushes and some blackbirds specialize in these intricate cup nests, and the nest of each species is unique. Size varies from tiny and delicate hummingbird nests, to large and chunky cup nests built by shrikes and crows. Cup nests are usually perfectly round structures, beautiful in their construction, woven of vegetation and lined with soft feathers or fluffy plant matter; some may be held together by a combination of other materials, like mud or spider silk.
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| Anna's Hummingbird on her tiny cup nest, which is held together with spider silk and camouflaged with pieces of lichen. |
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| Plumbeous Vireos suspend their cup nests between forked branches, lining them with grasses and covering the outside with cocoons, catkins and lichens. |
In a habitat largely devoid of trees and shrubs, grassland birds like Horned Larks and Meadowlarks build their cup nests directly on the ground, usually in the shelter of tall grass or other prairie plants.
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Horned Lark cup nest, placed on the ground in its grassland habitat.
(It's a wonder to me that any of these vulnerable ground nesting birds are successful, but they are!) |
One of the most incredible types of nest is the woven nest. A number of North American birds create woven nests, including Marsh Wrens and some orioles. The Old World family of birds known appropriately as the weavers construct some of the world's most amazing woven nests.
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| A Marsh Wren and it's impressive woven nest, firmly fastened to tule reeds. |
The nests of Cactus Wrens aren't truly woven, but
globular, round-ish masses of plant fibers, nestled deep in the protective spines of cacti and accessed by a small, round entrance hole. Inside, the nest opens up into a larger area lined with feathers. Other birds that build well-protected, enclosed globular nests such as this include the Verdin, Rose-throated Becard, American Dipper and Ovenbird (though each of these nests are marvelously unique as well!) The big, bulky nests of magpies are built along these lines as well.
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| The globular nest of a Cactus Wren, protected by the formidable spines of a cholla cactus. |
Similar to woven nests are hanging nests like those built by Bushtits. These long, pendulous nests look somewhat like dirty gym socks hanging in the trees, with a rounded "toe" at the bottom and an entry hole higher up near the top. These hanging nests are usually a foot or more in length, and may take over a month to build. Using strong and stretchy spider silk, the tiny birds stretch an initially cup-shaped nest downward by sitting in it while they continue to build the sides of the nest upward.
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| The hanging nest of a Bushtit (notice the entry hole near the top). |
Mud nests are brilliant little feats of engineering, carefully tucked underneath overhanging cliffs, building eaves, and bridges. Built mouthful by mouthful, swallows and phoebes construct their cup- or gourd-shaped nests using over a thousand mouthfuls of mud, returning each year to refurbish and reuse nests from previous years.
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| The mud nest of a Barn Swallow |
While Barn Swallows tend to nest singly, Cliff Swallows nest in large colonies, with hundreds or even thousands of nests clustered together under bridges or eaves, in culverts or caves, and on cliffs or dams, typically near a source of water.
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| Cliff Swallows in their nests under a protective gable. |
Quite a few species, swallows and phoebes included, frequently make use of man-made structures when choosing their nesting sites and, unfortunately, some people consider this a nuisance rather than a blessing. If at all possible, leave the birds alone and allow them to go about their business; feel honored that they chose your home as a safe nesting site, enjoy the experience of seeing nature up-close, and know that the inconvenience is only temporary: they will be out of the nest in about a month.
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| Eastern Phoebes, just about ready to fledge from their nest on a convenient man-made structure. |
Many species of birds are cavity nesters, choosing to build their nests in the relatively safe confines of natural or man-made cavities. The list of North American cavity nesters is long. Most notably, and at the top of the list, are the primary cavity nesters - woodpeckers, flickers and sapsuckers - which are the chief excavators of many nest cavities that are later used by other species.
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| Northern Flicker, a primary cavity nester, peeking out of its nest cavity |
There are a whole host of secondary cavity nesters as well, species that don't excavate their own nest cavities but rely on natural cavities that have formed in decaying wood, abandoned woodpecker holes, and manmade nest boxes and other nooks. These species include a few ducks (surprisingly), Tree and Violet Green Swallows, American Kestrels, bluebirds, nuthatches, chickadees, some flycatchers and even some small owls!
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| American Kestrel, a secondary cavity nester, in a man-made nest box. |
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| Western Bluebird, a secondary cavity nester, in a manmade nest box. |
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| Western Screech-owl, a secondary cavity nester, in a natural cavity. |
A few diverse species of birds nest in underground burrows. While Burrowing Owls rely on other animals, like ground squirrels and prairie dogs, to do the digging for them, puffins and storm-petrels dig their own burrows among the rocks and vegetation of wave-battered coasts and islands. Bank Swallows and Belted Kingfishers also dig burrows, but instead of burrowing into the ground, these species excavate nesting tunnels horizontally into the vertical cliff faces of riverbanks and bluffs.
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| A Burrowing Owl, outside its burrow, which was kindly dug by California Ground Squirrels. |
Clearly, diversity in bird nests is nearly limitless! While birds as a group have been expertly designed to adapt to just about every habitat on earth, their nests are also exquisite examples of design in nature: Each bird knows just how and when to build the perfect nest, in the best location, with the material available, that will just suit its family.
This spring, I hope you, too, are able to spend some time marveling at the wonders of bird and their amazing nests!
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