Fecal Sac Removal
Congratulations to Leah Goat, the first of many Naturally Curious readers to correctly identify the puffy, white matter in the Mystery Photo as a bird’s butt. Avian parents have solved the diaper dilemma – they just do without. However, a nest filled with fecal matter is a health threat to nestlings as well as a magnet for predators and parasites. Many songbirds have evolved an efficient strategy to discourage this situation, one of which includes the cooperation of their young.
Some nestlings do everything in their power to enable their parents in their endeavor to maintain a feces-free nest. Within seconds of being fed they assume a position with their butts front and center at the opening of their nest cavity. Once in position, the chicks produce fecal matter from their cloaca that is enclosed in a clear or white membrane called a fecal sac. The parent immediately clasps the emerging sac in its beak and either eats it or flies off and drops it far enough away so as not to attract predators. Nestlings stop producing fecal sacs shortly before fledging. (Photos: Tree Swallow removing fecal sac of nestling)
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Wood Ducks Returning To Northern New England
A welcome sign of spring in northern New England is the return of the Wood Duck to wooded swamps and wetlands. There are seven species of North American ducks that regularly nest in cavities and the Wood Duck is uniquely adapted for doing so. Its slim body allows it to use Pileated Woodpecker cavities for nesting and the acuity of its large eyes allows it to avoid branches while flying through wooded areas. Even so, it still tends to make one look twice to see ducks perched up in a tree!
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Common Goldeneye Ducklings Fledging
Common Goldeneyes, also called “Whistlers” because of the noise their wings make in flight, are a boreal-nesting species of duck. The eyes for which Common Goldeneyes are named have’t always been gold! They are gray-brown at hatching and turn purple-blue, then blue, then green-blue as they age. By five months of age they have become clear pale green-yellow. Adult males have bright yellow eyes, and females pale yellow to white.
Like Wood Ducks, Buffleheads and Hooded Mergansers, Common Goldeneyes are cavity nesters. When it’s time to fledge (24-36 hours after the young hatch), the female flies repeatedly to the nest hole, and eventually sits below the cavity calling to her precocial young. They jump from the nest in rapid succession, joining her in the water if the tree is on the shoreline, or on land (they nest up to 8/10ths of a mile from water) if not.
The young swim and feed with ease immediately, and are diving within one to two days of leaving the nest. The female protects them and broods them at night and during bad weather for the first few weeks. Even so, up to 56% of the young perish during their first week of life due to weather and predation. (Thanks to Jody Crosby for photo op.)
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Hooded Merganser Ducklings On The Water
It’s hard to picture a duck flying straight into a cavity in a tree, but there are several species of waterfowl that do just that in order to incubate their eggs in a relatively safe location. The female Hooded Merganser selects a nesting site in a living or dead tree cavity or in a handmade nest box. Once mating and egg-laying has occurred, the male disappears, leaving his mate to raise and care for their offspring.
Within 24 hours of her eggs hatching, the female calls to her young from the cavity opening or from the water below, encouraging them to leap up to the opening and hurl themselves out into the world. The entire brood departs the nest within a couple of minutes. As soon as they hit the water, the precocial young ducks are swimming, diving and feeding on water boatmen, backswimmers, diving beetles and other aquatic invertebrates.
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American Kestrel Chicks Fledging
The American Kestrel is the smallest, most numerous, and most widespread North American falcon. Roughly two months ago these birds (formerly known as Sparrow Hawks) were mating and laying eggs in nesting cavities (natural tree cavities, woodpecker holes, nest boxes), most of which are located near open fields with low growth (to facilitate finding insects to eat). The female kestrel does most of the incubating of her four to five eggs (one month), and all of the brooding (one month). The male rises to the occasion and feeds the newly-hatched chicks for the first 7-10 days, and then the pair shares the feeding.
After 26 – 28 days in the nest, American Kestrel chicks are ready to fledge. Their first flight, consisting of alternate fluttering and gliding, can be quite short or as long as 200 yards, and typically ends with an awkward landing. After the chicks have fledged, the parents continue to feed them for up to 12 days. During this period young American Kestrels have been observed returning to their nest cavity to roost.
(Photo: Male American Kestrel nestling, roughly 22 days old. Note feathered “eye” spots on back of head (serve to ward off predators) are already showing. Thanks to Joan Waltermire, John Douglas, David Merker, and Sebastion and Carter Lousada for photo op.)
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Downy Woodpeckers Nest-building
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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Cavity-nesting Birds Wasting No Time
There 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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Wood Ducks Returning
Among the first groups of birds to move north in the spring are waterfowl. Many ducks, geese, and swans begin migrating as soon as frozen lakes and marshes start to thaw. Although an occasional Wood Duck is spotted in northern New England during the colder months, most winter further south (band recoveries indicate that in eastern U.S. about one-third of Wood Ducks are permanent residents and the others are migratory). They begin to be seen in open water in February and March but it is April before their numbers really swell, and sometimes it seems that on every stream and in every flooded field you can find at least one pair. With their distinctive plumage, it’s hard to miss them, especially the males. Soon they will be seeking out natural cavities in trees, including Pileated Woodpecker holes, in which to nest.
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Hooded Merganser Ducklings on the Water
Hooded Merganser ducklings typically leap from their cavity nests in trees within twenty-four hours of hatching. Long claws on their feet aid them in climbing up to the opening of the cavity in order to join their mother who is calling from below. The ducklings feed themselves (aquatic insects and invertebrates) from day one, and are capable of shallow dives as soon as they leave their nest. The mother (who has been their sole caretaker since she started incubating the eggs) often moves her brood downstream to larger lakes, rivers and bays from smaller streams and ponds near the nest site. Eventually she leaves her young, anywhere from a month or two after they hatch, often before they can fly.
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Barred Owl Chicks View The World For The First Time
Barred Owl eggs (usually two or three) are often laid in a tree cavity, where the adult female incubates them for roughly a month. Fuzzy, white, downy chicks hatch and remain inside the tree for four or five weeks while being fed by both parents. When the young owls are two or three weeks old, their white down is replaced with gray-buff secondary down, and they gain the strength to climb up the inside of the tree and peer out at the outside world. In and out they go, perching on the rim of the nest hole for half an hour or so as they await the arrival of their next meal, and then retreating back to the safety and warmth of their nest. (Thanks to Alfred Balch, naturalist extraordinaire, for photo op.)
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Early Nesting Hooded Mergansers Seeking Tree Cavities
In northern New England you are most likely to see Hooded Mergansers in the spring and fall when they are migrating to and from their breeding grounds in northern Canada (some nest in New England, as well). Hooded Mergansers tend to arrive in their breeding areas as soon as the ice starts to melt, and have been known to start laying eggs in March in Massachusetts and April in Vermont. Often some of the earliest eggs laid in a nest will freeze and crack and never hatch.
Hooded Mergansers are cavity nesters, frequently choosing trees that are close to ponds, marshes, swamps or streams. They compete with Wood Ducks for nest boxes put out by humans, and females of both species may lay eggs in the same nest, with one or the other incubating the eggs. Sometimes the duck that initiated the nest does the incubation, but more often the hen laying the majority of the eggs will do so. Because both species have the same incubation period, all the eggs hatch at the same time.
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Black-capped Chickadees Still Nest-building
Black-capped Chickadees tend to be early nesters, often as early as April, as they build their nest inside a cavity where it is sheltered from the cold. Chickadees rarely re-use a nest, so one might guess that this Black-capped Chickadee with nesting material in its beak in early July has a second brood on its way. However, it is unusual for Black-capped Chickadees to have a second brood of young after the first has fledged. If they lose the first brood, they sometimes will re-nest, but it’s more likely that this chickadee is just a late nester, as nest-building can and does occur up until mid-July. Both members of a pair excavate a cavity in a rotting tree, stump or post and then the female alone builds the nest inside the cavity. The foundation of the nest is usually made of coarse material such as moss. The lining consists of softer, finer material such as deer hair, rabbit fur, or in this case, an aging chocolate Labrador Retriever’s hair.
Beaver Ponds & Waterfowl
The relationship between beavers and waterfowl is a strong one. In creating ponds and wetlands, beavers provide valuable waterfowl habitat. Beaver ponds are attractive to most dabbling duck species, particularly American Black Ducks and Mallards (pictured). Dead snags that are often found in beaver ponds provide Hooded Mergansers, Common Goldeneyes, Buffleheads and Wood Ducks with nesting cavities. During spring and fall, beaver ponds are used by migrating waterfowl, such as Green-winged Teal and Ring-necked Ducks, for the fuel they provide (aquatic invertebrates, plant seeds, tubers, buds and rhizomes). Waterfowl surveys in 2002 in Wyoming found that rivers and ponds with beavers had 75 times more ducks than those without beavers.
Hairy Woodpeckers Raising Young
The chipping of hungry Hairy Woodpecker nestlings can easily be detected by human ears, even though it comes from deep within a tree cavity. One is reminded of how beneficial this species is when observing the steady delivery of food by these woodpeckers to their young. More than 75% of an adult Hairy Woodpecker’s diet consists of injurious insects, while the amount of useful insects and cultivated fruits that they destroy is insignificant. Beetle larvae (mostly wood-boring) make up 30% of the insects that are consumed, with ants ranking second, at 17%. Caterpillars, such as those pictured, comprise about 10% of an adult Hairy Woodpecker’s diet, but given this parent’s beakful, one wonders if the percentage is greater for nestlings.
Hooded Merganser
Yesterday’s mystery duckling was a Hooded Merganser. Wood Duck and Hooded Merganser ducklings are very similar, however Wood Duck young possess a dark, horizontal line behind their eyes which Hooded Merganser ducklings lack. There are several ducks that nest in tree cavities in New England, including Wood Ducks, Common Goldeneyes, Common Mergansers and Hooded Mergansers. Hooded Merganser ducklings leave their nest cavity within 24 hours of hatching, in response to their mother’s calls below. They jump/climb up the wall of the cavity and hurl themselves out of the tree. Depending on where the tree is located, they fall either onto the ground, where they bounce like a tennis ball upon landing, or straight into the water. Hooded Merganser fledglings have been known to fall as far as 50 feet to the ground and then walk as far as half a mile with their mother to the nearest body of water.
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