Eastern Kingbirds Building Nests
Female Eastern Kingbirds are busy building nests and in about a week they will be laying clutches of three or four eggs. It is unusual for these birds to have a second brood. A small clutch and a single nesting period translate into fairly low productivity for this species.
Ornithologists suggest that the Eastern Kingbird’s low reproductive rate is related to the fact that they rely heavily on flying insects for food, the supply of which can be limited if cool, wet weather occurs. In addition, Eastern Kingbirds care for their young for three to five weeks after the young fledge, longer than many species of birds. This also limits the time available for a second brood.
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Black-capped Chickadees Nest-building
Spring is here and nest building has begun for many of our cavity nesters. Protected from the wind and low temperatures that can occur this time of year, birds that nest in cavities get a jump start on starting a family. Black-capped Chickadees typically seek out trees with punky wood that is soft enough for their small beaks to excavate. Birch, aspen and sugar maple are chosen with regularity.
While the nest site is often chosen by the female, both male and female chickadees participate in the excavation of the cavity. They take turns disappearing inside the hole (that they have created or one that a previous nesting woodpecker made or a natural cavity) and chipping away at its interior and then exit with a beak full of wood chips. Unlike many cavity nesters that just drop the chips to the ground from the hole, chickadees usually fly a short distance away before dropping them.
The female alone builds the nest inside the cavity. She usually uses coarse material such as moss for the foundation, and lines the nest with finer material such as rabbit fur and deer hair. Within one to two days of finishing the nest, she lays anywhere from one to thirteen eggs.
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Snow Buntings: Winter Visitors From The Far North
This Snow Bunting, feeding on farm silage in the Champlain Valley, migrated from the high Arctic to spend several winter months in Vermont where temperatures are comparatively warm and food is more available. In about two months he and other males will return to the arctic to nest in temperatures as cold as -22°F., where most of the seeds that they feed on are still covered with snow. Females will migrate back to their breeding grounds four to six weeks later.
Why do male Snow Buntings depart from warmer winter climes to begin their breeding season in such a hostile environment? They do so because competition for their rock crevice nest sites is so severe. Typically arctic songbirds nest in the open, but the eggs and young of crevice-nesting Snow Buntings experience far less predation than those of other birds. Even though their nests are lined with fur and feathers, these cracks and crevices can be quite cold and detrimental to developing eggs, so the male buntings feed their mates during incubation so that the incubating females can remain on the nest for long periods, keeping their eggs warm.
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Species Specific Nests
Snow falling on abandoned bird nests forms distinctive white caps that are easy to detect. Because the builders of these nurseries are long gone, most with no intention of re-using their nest, we are afforded a unique opportunity to get a bird’s eye view of them.
There are many clues that help to identify the builder of a nest — habitat, size, and material used being the most obvious. A given species of bird builds a nest that greatly resembles the nest of every other member of that species, and builds it in a similar habitat. Thus, every American Goldfinch nest bears a strong resemblance to every other American Goldfinch nest, every Gray Catbird nest looks like every other Gray Catbird nest, etc. The two American Goldfinch nests pictured were both located in overgrown fields, they are both roughly three inches wide and a little over that in depth, and both are made of fine fibers and lined with thistle and cattail down.
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Ospreys Continue To Add Material to Nest Throughout The Nesting Season
The nesting season for Ospreys is well underway – chicks appear larger by the day, and before long they will be fledging. As advanced as the nesting season is, Osprey nests are still being reinforced with material retrieved by the adults.
The pictured Osprey took off from its nest, swooped down to a nearby roadside and scooped up a sizable clump of mowed grass with its talons which it then delivered back to its nest where its mate was sitting with two chicks. Even late in the nesting season all manner of material, not all of it natural, is added to Osprey nests – among other things, paper, plastic bags, rope, nylon mesh bait bags, dried cow manure and beach toys have been documented.
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American Redstarts Co-Parenting
American Redstarts, lively and colorful little warblers, share much of the parental care of their young. He selects and presents her with a choice of nest locations. She chooses the site and builds the nest. He feeds her while she incubates the eggs. Both parents collect insects and feed their nestlings as well as remove fecal sacs (small packets of waste produced by nestlings). She does much of the brooding of the young. When their young fledge, the mother and father divide responsibility for the fledglings, with each parent separately caring for a portion of the young.
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White-breasted Nuthatches Nesting
White-breasted Nuthatches are one of the 85 species of North American birds that are classified as cavity nesters. Although the young of birds nesting in cavities are protected from the elements, they are still vulnerable to predators.
White-breasted Nuthatches have an unusual strategy for discouraging uninvited guests. They “bill-sweep” with an object, usually a crushed insect, in their bill, sweeping back and forth on the tree both outside and inside the nest, often for many minutes at a time. It’s thought that chemical defense secretions from the crushed insect may discourage squirrels from entering the cavity. (Red-breasted Nuthatches apply sticky conifer resin to both the inside and outside of their nesting cavity, which presumedly serves the same purpose.)
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Great Blue Heron Ingenuity
I had to laugh this morning about what I witnessed just after posting about male Great Blue Herons collecting and delivering sticks for their nest. It occurred to me that I have seen hundreds of sticks being brought to nests, but I have never actually seen a heron in the act of collecting a stick. Lo and behold, today was my lucky day. At least one heron came up with an extremely efficient and energy-saving strategy for accomplishing this task.
Being largely fish eaters, herons typically raise their young in wetlands where food is plentiful. Many of these wetlands are created by beavers, who set up housekeeping there as well. Herons owe not only their habitat to beavers, but also, in this case, their nesting material. A veritable goldmine of sticks is right underneath the heron nests, free for the taking right in the middle of the heron rookery in the form of a beaver lodge. Fortunately for the beavers, there is a limit to the size of the stick a heron can carry.
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Great Blue Herons Renovating & Building Nests
Great Blue Herons are colonial nesters – up to 500 platform nests or more may be built in dead snags and trees bordering or in swamps, ponds and woodlands. Where trees are not available, they will nest on the ground (this usually occurs only on predator-free islands).
The nests of Great Blue Herons are built of sticks, usually gathered by the males from nearby trees and shrubs as well as the ground. The male heron flies with a stick in his bill back to the nest (see photo) where the female awaits and presents her with the stick. She takes it from his beak, pokes it into the nest and eventually lines the nest with pine needles, moss, reeds, grasses and small twigs. Although nest building and repair is at its height right now, nesting material is added throughout the nesting period.
Nests are often re-used for many years, but not necessarily by the same pair of herons. While nest fidelity is not strong, Great Blue Herons do tend to show a preference for the species of tree in a colony in which they build their nest. Nesting colonies can be used for just a few years, or for as many as 70.
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Male Red-bellied Woodpeckers Calling & Tapping To Attract Mate
One of the best ways to determine if Red-bellied Woodpeckers have chosen to nest nearby is the presence of their persistent and distinctive “kwirr” call. It is given most often now, during the breeding season, when males try to attract a mate to their roost cavity or a partially completed excavation by calling to them. Drumming and soft taps are also performed by males as part of the courtship ritual.
When attracted, the female flies to the male and indicates her acceptance of his cavity by perching beside him while they both engage in tapping behavior. If the cavity is partially completed, the mutual tapping behavior also appears to stimulate the female to help the male finish excavating the cavity. (Photo: male Red-bellied Woodpecker at nest hole; inset: male (left) and female (right) tapping at nest hole.)
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Brown-headed Cowbird: Brood Parasite
One has to admire a creature who has managed to eliminate the laboriousness of raising its offspring. Brown-headed Cowbirds, renowned brood parasites, have done just that. These birds do not build nests; females lay up to 40 eggs a summer in the nests of more than 220 species of birds which raise their young for them. Cowbird eggs are generally larger than the host bird’s and hatch in fewer days, thereby putting Cowbird chicks at a distinct advantage over the host’s chicks when it comes to parental attention.
In this photo a Brown-headed Cowbird has deposited three eggs in the nest of an Eastern Phoebe (which has constructed its nest inside an abandoned American Robin nest). Unlike some songbirds, Phoebes do not recognize and remove the Cowbird’s eggs. Neither do they build a new nest on top of the old one, as some smaller songbirds (i.e. Yellow Warblers) are known to do.
Cowbird chicks develop faster than the chicks of the host bird, thereby often getting the first crack at the food parents bring to the nestlings. Not only are the host species’ chicks often at a disadvantage when it comes to parental care, but they are at the mercy of the Cowbird chicks which often remove both the eggs and chicks of the host. (Thanks to friends in Thetford, VT for the use of their photograph of this parasitized Eastern Phoebe nest. The three larger, speckled eggs are Brown-headed Cowbird eggs; the four smaller white eggs are Eastern Phoebe eggs.)
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Northern Cardinal Nests: Safety in Numbers
This is the time of year to keep an eye out for bird nests that were hidden by leaves all summer. Their location can reveal more than one might guess. As with many bird species, the female Northern Cardinal does most of the nest-building herself, usually selecting a site that is in dense shrubbery, often in a tangle of vines. Frequently there are two broods, but rarely is a nest reused. Instead, a new nest is built for the second clutch of eggs, and it can intentionally be located quite close to the first nest.
The two pictured Cardinal nests were both built this year, only four feet apart in a grape vine-covered stand of Staghorn Sumac. Two different birds would not have nested so close to each other due to territoriality; thus, the same bird most likely built both nests. Ornithologists feel that the presence of old nests may function as protection against predation. They found that when they placed an empty Cardinal nest adjacent to a Cardinal nest containing plastic eggs, there was significantly less predation than with single Cardinal nests. (Thanks to Jody Crosby for photo opportunity.)
(NB: Even though most songbirds only use their nest once and then abandon it, one needs a federal permit to collect bird nests.)
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Northern Cardinal Nests: Safety In Numbers
This is the time of year to keep an eye out for bird nests that were hidden by leaves all summer. Their location can reveal more than one might guess. As with many bird species, the female Northern Cardinal does most of the nest-building herself, usually selecting a site that is in dense shrubbery, often in a tangle of vines. Frequently there are two broods, but rarely is a nest reused. Instead, a new nest is built for the second clutch of eggs, and it can intentionally be located quite close to the first nest.
The two pictured Cardinal nests were both built this year, only four feet apart in a grape vine-covered stand of Staghorn Sumac. Two different birds would not have nested so close to each other due to territoriality; thus, the same bird most likely built both nests. Ornithologists feel that the presence of old nests may function as protection against predation. They found that when they placed an empty Cardinal nest adjacent to a Cardinal nest containing plastic eggs, there was significantly less predation than with single Cardinal nests. (Thanks to Jody Crosby for photo opportunity.)
(NB: Even though most songbirds only use their nest once and then abandon it, one needs a federal permit to collect bird nests.)
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Marsh Wrens Nesting
More often heard than seen, the Marsh Wren has a distinctive song that quickly alerts you to the fact that they are nesting in the area. Sung by the male at dawn, dusk and sometimes throughout the night, the song is a rapid series of gurgling and buzzy trills. Though each note may only last for 1–2 seconds, they can sing continuously for up to 20 minutes, rarely repeating the same note. To hear their song go to https://www.allaboutbirds.org/guide/Marsh_Wren/sounds .
Even though their nests are plentiful (males build multiple nests) they are well hidden and difficult to detect in amongst the cattails and bulrushes where they are built. About 50% of males mate with two or more females and most males build at least six dummy nests for every female they mate with. (In some parts of their range males build an average of 22 nests.) Scientists aren’t sure why the males build so many dummy nests – perhaps as decoys for predators. They are built two to five feet above the ground and are about 7” tall and dome-shaped with an entrance hole in the upper half. Once the female has chosen one of the male’s nests or built her own, she lines it with strips of grass, sedge, cattail down, feathers, and rootlets.
Possibly as a result of intense competition for resources in the marsh environments in which they nest and raise young, Marsh Wrens routinely destroy the eggs of other birds, including other Marsh Wrens. (Note: Pictured active Marsh Wren nest was built in rushes, which are preferred over cattails later in the nesting season, when cattails have dried out.)
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Osprey Nesting Behavior
Naturally Curious is back! Different ecosystem (western vs. eastern Vermont) but same curiosity! This week’s posts are going to be devoted to the nesting behavior of the Osprey — the only raptor that plunge-dives feet first to catch live fish as its main prey source.
Ospreys nest within six to twelve miles of water (usually much closer). The male collects most of the nesting material and brings it to the nest site where the female arranges it. Sticks as large as an inch-and-a-half in diameter and three feet long are collected from the ground, or (less commonly) snapped off a tree while the Osprey is in flight. Nest-building continues throughout the incubation of the eggs as well as the brooding period — even if a nest fails, Ospreys will continue to add material to it.
Although nests built on platforms are relatively small, those built in trees or on the ground can be 10 -13 feet deep and 3 – 6 feet in diameter (the largest nests are most likely the result of several generations of nesting Ospreys). The shape of an Osprey nest changes during the breeding cycle. When the eggs are being incubated, the nest is bowl-shaped. After hatching the nest flattens out, but a rim of sticks is maintained. By the time the nestlings fledge (around 50-55 days) the nest is often completely flat.
Ospreys will reuse their nest year after year, saving themselves time and energy which allows earlier laying and more surviving young. Birds whose nests fail are likely to build alternate nests and use them in subsequent years. (Birds of the World Online).
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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
When 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
Nestling 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
Once 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
Recently 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
After 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
One 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?
It’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
Great 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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