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Bird Nests

Bird Nests Revealed

Deciduous leaves have fallen, revealing bird nests that were right under our noses all summer without our even knowing it.  In addition to building in specific habitats and constructing different sized nests, each species of bird uses a combination of building material that is slightly different from every other species. Because of this, the material a bird uses to construct its nest can be diagnostic as far as determining what species built the nest.  Is the nest lined with rootlets? Are grape vines incorporated into the nest? Is moss covering the outside of the nest?  Is there a shed snake skin woven into the nest? The answer to these questions and others can help narrow down the list of possible builders.

This is the time of year to look for nests and try to determine, with the help of a good field guide such as Peterson’s Field Guide to Bird Nests, the identity of the birds that built them.  (Be aware that possession of a bird nest, egg or feather of most migratory birds, even for scientific research or education, is illegal if you do not have a Federal Migratory Bird Scientific Collecting Permit.)

Sometimes you’ll find material in nests that surprise you — some contain man-made, as well as natural, materials. Among the most unusual examples of this are a nest built solely out of barbed wire by a Chihuahuan raven in Texas and the pictured clothes hanger nest built by a crow near Tokyo and photographed by Goetz Kluge.

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Pileated Woodpeckers Fledging

7-5-19 junior about to fledge 0U1A0832When your children start to get this feisty, it’s time for them to leave the nest!

Between three and a half and four weeks of age, Pileated Woodpecker nestlings fledge. Their flight feathers are about 75% of adult size when they depart. Some fledglings are capable of sustained flight when they leave the nest, while others may need several days before they can fly any distance.

Initially parents and siblings stay in the vicinity of the nest, but once the young can fly well, they follow adults everywhere. All the young may stay with both parents, or the parents may split up and each take some of the young. The fledglings will remain with their parents into September. (Photo: male Pileated Woodpecker nestling about to fledge while his father watches.) Much gratitude to Amber Jones and Dave Bliven for sharing their deck, their sweet dog Briggs and their magnificent view of this Pileated Woodpecker family with me.

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Pileated Woodpecker Parents Regurgitating

7-3-19 pileated feeding 0U1A0222Nestling meals consist primarily of invertebrates. Adult Pileated Woodpeckers feed their young by regurgitation, inserting their bill quite far into the throats of their young as they deliver food to them. A visit can consist of one to three regurgitations per nestling. (Photo: adult male Pileated Woodpecker feeding male nestling)

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Pileated Woodpeckers Raising Young

7-2-19 pileated and young 0U1A0579Once their eggs (usually 3-5) hatch, Pileated Woodpeckers, like all parents, are kept busy providing their young with food. The nestlings are fed about every hour when small, but this stretches to every two hours after the nestlings are about a week old.

At first the adults enter the cavity to feed their young and only the tips of the parents’ tails are visible. Eventually the young manage to reach the cavity opening and can be seen at the entrance to the nest hole, waiting for food to be delivered. As they age, the nestlings find their voice when hungry and the woods reverberate with their distinctive and very adult-like call (https://www.allaboutbirds.org/guide/Pileated_Woodpecker/sounds). (Photo: female adult Pileated Woodpecker and male nestling)

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Changing of the Guard: Pileated Woodpecker Parents Share Parenting Duties

7-1-19 male and female pileated 0U1A0116Recently I had the opportunity to observe nesting Pileated Woodpeckers, and I thought I would devote this week’s Naturally Curious posts to different aspects of my observations. I would like to thank Amber Jones and Dave Bliven for generously sharing their Picidae residents with me.

From start to finish, both Pileated Woodpecker parents are involved in raising their young and all that it entails. Together they excavate a nest cavity, usually in a dead or dying tree. Both have brood patches (areas on their undersides that lack feathers and are well supplied with blood vessels, allowing efficient transfer of body heat to eggs), and both incubate the eggs during the day (the male has night duty). The parents take turns brooding the nestlings and providing them with food. And finally, once fledging take place, both parents provide and help their young find food for several months. (Photo: male Pileated Woodpecker in nest cavity; female Pileated Woodpecker on nesting tree)

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Baltimore Orioles Fledging

6-28-19 baltimore oriole family 0U1A0415After arriving back in Vermont in May, Baltimore Orioles mate, build their nest (female only) near the tip of an outer branch of an isolated tree (discouraging predation), lay eggs and incubate them for about two weeks before they hatch.

After spending the next two weeks in the nest, most nestlings are ready to fledge. It is at this point that you can actually see the nestlings as they cling to the outside of their pendulous nest, or perch on its rim as they noisily await the arrival of a parent with an insect morsel. Upon fledging, they can fly, but not very far. The parents will continue to keep an eye on them and feed them during these vulnerable first two weeks out of the nest until they can fend for themselves. (Many thanks to Nina and Jerry Hickson for photo opportunity.) (Photo: Male (topmost bird), female and nestling Baltimore Oriole)

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Black-and-White Warblers Raising Young

6-14-19 black-and-white warbler nest 0U1A0066One of the first warblers to return to its northern nesting grounds, the (female) Black-and-White Warbler has already built a nest, laid and incubated 4-6 speckled eggs and is now brooding and feeding nestlings.

Finding a Black-and-White Warbler nest can be challenging – these bark-foraging insect eaters usually build their well-hidden nest on the ground at the base of a tree, rock, stump or fallen log. Tucked into vegetation with the rim often at ground level, their 5-inch diameter nest blends into its surroundings. Bark strips, grass, dry leaves and pine needles are used to construct the nest which is lined with moss, horsehair and dried grasses.

The male helps the female feed the nestlings and defend the nest. Female Black-and-White Warblers have been observed performing “rodent run” distraction displays, in which the bird assumes a hunched posture and drags its tail, luring potential predators away from the nest.

The Brown-headed Cowbird is a major threat to Black-and-White Warblers as it frequently parasitizes their nests. One documented Black-and-White Warbler nest in Michigan contained 10 eggs, eight of which were laid by cowbirds. (Thanks to Susan and Dean Greenberg for photo opportunity.)

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Why Do Birds Turn Their Eggs?

5-31-19 C. goose turning eggs 1B0A8783It’s common knowledge that birds periodically turn their eggs when they are incubating them, but have you ever stopped to ask why they do this. One assumes that if this action weren’t critical to the incubation process, it wouldn’t be practiced, and science bears this out. According to Audubon, birds turn their eggs to make sure the embryo gets enough albumen – the white part of the egg that contains water and protein and provides essential nutrients to the developing embryo. Too little albumen leads to an underdeveloped and often sickly chick. (Photo: Canada Goose turning eggs)

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Great Horned Owl Nestlings About To Fledge

5-17-19 great horned owls_U1A8938Great Horned Owls do not build their own nests, though they may provide some lining to an existing cavity or nest. Snags, cliffs and man-made structures provide nesting sites, but most commonly Great Horned Owls use the tree nests of other species such as hawks (especially Red-tailed) crows, ravens and squirrels. Most, but not all, nests are used for only one season. Pictured is a Great Blue Heron nest that has been usurped by a Great Horned Owl family – a feat achieved by the owls claiming the nest as early as February, prior to the return of herons.

After incubating her eggs for roughly a month, the female Great Horned Owl then broods her young for two to three weeks. The father’s role consists of bringing food to the female while she is incubating and brooding. She then tears the food up into bite-size pieces for the nestlings.

When the nestlings no longer need the heat their mother’s body provides, brooding ends but the mother stays with her nestlings until they fledge at about seven weeks of age. (Pictured: Great Horned Owl mother and two downy nestlings, roughly six weeks old. Thanks to Marc Beerman for photo op.)

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Great Blue Herons Building & Renovating Nests

5-6-19 great blue heron with white pine2_U1A7932A visit to a Great Blue Heron colony at this time of year will be rewarded with a great deal of avian activity, for their nesting season has begun and renovations are going full tilt. Males usually arrive first and settle on nests (more often as not using a different nest from last year) or begin building their own. Courtship then begins.

Great Blue Heron nests are found primarily in trees, up to 60 feet or more above the ground. Where trees are not available, herons will nest on the ground (usually only on predator-free islands). Males gather sticks and other nesting materials from the ground, nearby trees and shrubs, or from unguarded and abandoned nests, and females are usually responsible for the placement of the sticks into the nest. Nests are often reused for many years. Pictured is a Great Blue Heron returning to its nest with a branch from a White Pine tree which will be used for lining the nest. Nesting material is added throughout the nesting period.

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Canada Geese Nesting On Beaver Lodges

4-29-19 c. goose on beaver lodge _U1A7241If you are fortunate enough to have a beaver pond near you, you should give the lodge more than a cursory glance this time of year. It is common to find Canada Geese nesting on beaver lodges, for obvious reasons – safety from most land predators. While Common ravens have been known to raid Canada Goose nests for eggs and goslings, the overall rate of survival of the goslings of lodge-nesting geese is very high.

A Canadian study showed that ponds with beaver lodges (and therefore Beaver activity which warms the water and thaws the ice) thaw at least 11 days sooner than ponds without Beavers, allowing early access to water for Canada Geese returning for the spring nesting season. Battles between pairs of geese vying for these coveted nesting sites are not uncommon.

Canada Geese have much to thank Beavers for. Not only can geese get an early nesting start on beaver lodges, they have a relatively safe spot to incubate their eggs and raise their young.

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Changing of the Guard

5-11-18 red-bellied woodpeckers3 _U1A2313

In approximately 85% of bird species, both the male and female of a mating pair contribute to the feeding and guarding of their offspring. Red-bellied Woodpeckers are of this ilk. Both members of a pair help excavate a nest cavity, incubate the eggs, brood the young and feed the nestlings for up to 10 weeks after they fledge. As seen in this photograph, when tending to their nestlings, one member of a pair wastes no time in departing as soon as its mate appears.

Thanks to the extension of the Red-bellied Woodpecker’s range northward, even northern New Englanders now have the opportunity to observe the nesting behavior of these medium-sized woodpeckers. (Photo: female Red-bellied Woodpecker leaves nest as food-bearing male arrives. Note continuous red crown on male, which is broken in female.) (Thanks to Sadie Brown for photo op.)

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Common Grackles Nest-building

4-23-18 common grackle 0U1A0687

Common Grackles are hard to miss and hard to mistake for any other bird, with their yellow eyes, iridescent bronze or purple plumage and long, keel-shaped tails. Most of the spring migrants have reached their breeding grounds, and courtship, mating and nest-building are underway.

Because grackles begin reproduction so early in the season, conifers are the nesting site of choice due to the cover they provide. Females tend to choose the actual site for a nest, and in so doing can be quite fickle, often abandoning partially constructed nests and selecting alternative sites. They earn this right, as they’re usually doing all the construction work, although males have been observed with nesting materials, helping to build and repair nests.

Look for their 6-8”-diameter, large bulky nests near water, agricultural fields or near human habitation. They are usually built four to twenty feet above the ground. If you find a bird on the nest, it will most likely be an incubating female (slightly less glossy than male) – males not only do not have a brood patch and do not participate in incubating the eggs or brooding the young, but roughly half of the males desert their mates during this time. Those that do remain participate in the feeding of their young nestlings.

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Downy Woodpeckers Nest-building

4-16-18 downy2 049A4077

Downy Woodpeckers are beginning to scout for potential nest sites, preferring the dead stubs of a living or dead tree. Both sexes have been observed selecting the nest site, although females do so more commonly. Just because you see a Downy Woodpecker pecking at a site, however, doesn’t mean it will end up nesting there, as excavation is often started at several sites before one is chosen.

When a potential nest site is decided upon by either sex, it often drums to inform its mate, and its mate often flies to the site and taps or drums in response. It takes about 16 days for both male and female to excavate a cavity. A round entrance hole of roughly 1 ¼” in diameter can make it hard for an egg-bearing female to squeeze into the nest. Egg-laying begins anywhere from one to ten days after the completion of the nest cavity, and three to eight eggs are laid, one per day, usually before 10 a.m.. (Photo: male Downy Woodpecker excavating nesting hole)

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Bald Eagles On Eggs

3-19-18 bald eagle2 049A4432

Thanks in large part to the Vermont Bald Eagle Restoration Initiative, seeing eagles in Vermont is not all that unusual these days, even in winter. The open water of Lake Champlain (as well as ice fishermen and White-tailed Deer carcasses in other parts of the state) allow them to survive here during our coldest months. Vermont’s mid-winter Bald Eagle Survey documented 84 eagles in January, 2018.

Equally as encouraging is the growing breeding population of eagles in this state. This past year 21 adult Bald Eagle pairs successfully produced 35 young in Vermont. The return of eagles to their nest site is always a much- anticipated event, which often coincides with the opening up of the Connecticut River for at least one pair that nests on its banks (see photo).

Eggs have been laid and eagles (both male and female) are engaged in incubating them for the next month.  One can’t help but be impressed by their perseverance — recently they endured three Nor’easters in 10 days while incubating their eggs (note snow on rim of nest)!

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Black-throated Blue Warbler Nests

11-20-17 black-throated blue nest 049A7357

It’s the lucky individual who happens upon a Black-throated Blue Warbler’s nest while it is in use, for these birds tend to build their nest directly under leaves which keep the nest very well hidden. Now that many of the leaves have fallen off shrubs and saplings, where Black-throated Blue Warblers typically build their nests, they (nests) are especially noticeable, being at eye level or below.

The female warbler builds the nest, using a variety of material including white and yellow birch bark for the outer layer (glued together with spider silk and saliva), shredded bark fibers for the inner wall and fine black rootlets, pine needles, bits of moss and strands of mammal hair (horse, skunk, human, moose, porcupine and deer) for the lining. This combination of material makes their nest very distinctive and relatively easy to identify.

 

 


Baltimore Orioles Building Nests

5-26-17 b oriole building nest2 243Although male Baltimore Orioles have been known to partake in nest building, usually it’s the female who selects the specific site within the male’s territory and builds the nest. Located at the tip of a slender branch, this pendulous nest provides its occupants with as much protection from predators as is possible.

The material with which the nest is started usually consists of flexible plant, animal or human-made fibers, and provides support. “Springy” fibers are then woven into the inner bowl and downy fibers are used to line the nest.  The oriole usually brings only a single fiber at each visit, and works it into the nest with a complex series of bill-weaving techniques. The nest is completed in roughly one week.

Construction material includes hair (especially horsehair), twine or string, wool, synthetic fibers (one oriole nest was made entirely of cellophane), various types of plant fibers including grasses, milkweed stems and grapevine bark, cottonwood or willow seed “cotton,” milkweed seed plumes and feathers. Females have been observed flying more than a quarter of a mile in search of construction material. (Photo:  Female Baltimore Oriole on her first day of nest-building)

YESTERDAY’S MYSTERY PHOTO: Once again, Naturally Curious readers outdid themselves with creative solutions to a Mystery Photo. If you want a thoroughly enjoyable 5 minutes of entertainment, read yesterday’s comments! I will let you know if this mystery is ever solved.

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Belted Kingfisher Nests

5-18-17 female kingfisher 025I unintentionally neglected to mention the diameter of the holes in yesterday’s Mystery Photo. They were approximately 5” wide. Bank Swallow nest holes, similar looking and also dug into banks, are anywhere from 1 ½” to 3” in diameter. Being colonial nesters, Bank Swallows also typically have many more nests in a given bank (see photo inset) than Belted Kingfishers, which usually have one but may have several in a single bank, only one of which they occurpy during a given season.

After courtship takes place, a pair of Belted Kingfishers flies to a sand bank in a road cut, landfill or sand/gravel pit that is usually near water, and proceed to excavate their nesting tunnel. The male begins to slash and probe the soil with his bill while the female remains perched nearby, calling the distinctive rattling call of Belted Kingfishers. She eventually lends a hand (bill) and they call to each other throughout the construction of their nest.

The tunnel extends three to six feet into the bank, ending with an unlined chamber. (A bed of undigested fish bones, scales and arthropod exoskeletons from regurgitated pellets eventually forms.) Typically the tunnel slopes upward from the entrance, which may help drain any water that accumulates in the nest. Furrows directly below the bottom of the nest hole are made by the feet of the birds as they enter and leave the nest.

Belted Kingfishers are starting to lay their six to seven eggs which will begin hatching in three to four weeks. (Photo:  female Belted Kingfisher)

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Cavity-nesting Birds Wasting No Time

4-21-17 black-capped chickadee nest building IMG_4765There are roughly 85 species of North American birds that are cavity nesters – birds that excavate nesting holes, use cavities resulting from decay (natural cavities), or use holes created by other species in dead or deteriorating trees.   Many of them get a jump start on open-nesting birds, due to added protection from the elements. Barred owls, titmice, chickadees, wood ducks, woodpeckers, bluebirds, mergansers – many have chosen a nest site and are busy excavating, lining a cavity or laying eggs long before many other species have even returned to their breeding grounds.

The reduced risk of predation a cavity nest experiences is reflected in several ways:  many cavity-nesters have larger clutches of eggs than open-nesting birds and cavity-nesting young also spend a relatively longer period of time in the nest before fledging. When in the woods, keep an eye out for snags (standing dead trees) and stumps, for they provide housing for many cavity-nesting birds.  (Photo: Black-capped Chickadee removing wood chips from the cavity it’s excavating in a rotting stump.)

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Red-tailed Hawks Building & Refurbishing Nests

3-16-17 red-tailed hawksIMG_2505

Red-tailed Hawks are on eggs, or soon will be.  Whether their nest is in the canopy, on a building ledge, transmission tower or elsewhere, it usually has a commanding view of the surrounding area and unobstructed access from above.

Both members of a pair share in nest site selection, which is often in mixed woods adjacent to open fields. They build their nest together, working most diligently in the morning, and construction is completed within four to seven days. If a nest is re-used, which it often is, it is refurbished with sticks and greenery. Red-tails are very wary during this nest-preparation period and may discontinue nest-building if humans are detected, so should you come upon a nest during this stage, best to remove yourself quickly.

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Winter Mouse House

11-14-16-mouse-house2-049a1332One of my very favorite animal signs is the winterized home of a Deer or White-footed Mouse. Most songbirds do not re-use their nests. Once the nestlings have fledged, what doesn’t get recycled directly from the nest by other birds or critters slowly disintegrates from rain and snow. That is, unless an agile mouse discovers it and renovates it first. Deer and White-footed Mice are known for using abandoned nests as larders (see  https://naturallycuriouswithmaryholland.wordpress.com/2013/10/25/mice-preparing-for-winter/) or as homes for the winter. For the latter, a roof is constructed, usually out of milkweed or cattail fluff, but I have even found man-made insulation used as construction material for a roof. (The pictured nest has been well insulated with a roof of cattail fluff.)

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Belted Kingfishers’ Distinctive Traits

8-2-16 belted kingfisher 520You often hear a Belted Kingfisher before you see it. Their territorial, mechanical “rattle” is quite distinctive and issued frequently.  This call is just one of their more distinctive traits.  They are one of the few species of birds where the female’s plumage (two “belts” on breast) is more colorful than the male’s (one breast “belt”). Kingfishers have a distinctive pattern of wingbeats: whereas most birds beat their wings several times and then glide, kingfishers’ wingbeats are irregular and intermittent, lacking the flap and glide pattern.  Kingfishers have the unusual ability to hover in one spot while surveying the water 20 to 40 feet below for fish or other prey.  When they capture a fish, they often return to a branch and whack it multiple times against the branch to assure its compliance in being swallowed head first without a struggle.  Even the nesting site of a Belted Kingfisher is fairly unusual —  a chamber located at the end of a 3 to 6-foot-long bank burrow they dig with their bill and feet.

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Changing of the Guard: Hairy Woodpeckers Sharing Parental Duties

5-30-16 hairy woodpeckers  215

When their offspring are very young, Hairy Woodpeckers feed them by regurgitation.  As the nestlings mature, the parents bring food back to the nest.  Most species of birds (85%) engage in bi-parental care, where the male and female contribute equally to feeding and guarding their young.  Often the male does more of the food gathering and the female more of the brooding.

In some of these species the male and female both brood as well as gather food.  Hairy Woodpecker parents share these duties equally for the month that their young remain in their cavity nest.  They both brood their young, with males typically getting night duty, and both gather food for their nestlings.  Lawrence Kilham, a New Hampshire MD and ornithologist, found that male Hairy Woodpeckers foraged farther from the nest, made fewer feeding visits, and brought larger prey to nestlings, whereas females remained closer and fed young three to four times as frequently as males.  (Photo: female Hairy Woodpecker arriving with arachnid food, male about to depart. Thanks to Suzanne Weinberg for photo op.)

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Wild Turkey Hens On Eggs

wild turkey nest 238

This is what a typical Wild Turkey’s nest looks like – anywhere from 4 to 17 eggs in a shallow depression in the ground.  Sometimes, however, turkeys engage in a practice referred to as “egg dumping.” A hen turkey comes along and lays a few eggs in several other turkeys’ nests, in an effort to maximize the number of her offspring that will survive.  Up to 26 eggs have been found in a single Wild Turkey nest.  The hen turkey that built the nest doesn’t reject the additional eggs, but rather, welcomes them to her brood, incubates them and treats them as her own.  All of the precocial chicks are out of the nest within 24 hours of hatching and follow the hen, who feeds them for a few days until they learn to find food on their own.

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