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Woodpeckers

Pileated Woodpecker’s Winter (and early spring) Diet

The mainstay (up to 60%) of a Pileated Woodpecker’s diet is Carpenter Ants (especially in the winter) with wood-boring beetle larvae (early spring) not far behind.  Flies, caterpillars, grasshoppers, termites, cockroaches and a variety of other insects are also consumed in summer.  However, these woodpeckers are not strictly insectivores.  During the fall and winter they seek out fruit (and nuts), including the fruit of Wild Grape, Virginia Creeper, Poison Ivy, Poison Sumac, American Holly, Elderberry, Blackberry, Raspberry, Hackberry and Crab Apple (pictured).  Roughly one-quarter of a Pileated Woodpecker’s diet may be fruits and nuts.  (Thanks to Sadie Brown for photo op.)

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Last of the Yellow-bellied Sapsuckers Migrating

Most of us in northern New England are probably seeing the last of the Yellow-bellied Sapsuckers that nested here this summer.   Unlike most species of woodpeckers (which are year-round residents), a majority of sapsuckers that breed this far north end up migrating further south; southern U.S. and Central America are where most of them overwinter. Females have been observed migrating before males, and spending the winter further south than males.  We don’t often see sapsuckers migrating, as they do so at night and are relatively quiet when flying.  Occasionally you may come upon one during the day resting motionless on a tree, or even briefly drumming.

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Northern Flickers Migrating

The Northern Flicker is one of the few North American woodpeckers that is strongly migratory. However,  most of the eastern migrants are Canadian breeders.  They fly south from Canada with big flights moving down the Atlantic coast in the fall to the southeastern U.S.. Peak fall migration occurs from late September to early October, with some migration continuing to early November. As a result, New England sees an increase in the number of flickers sighted at this time of year.  More southern populations are sedentary, and do not migrate. Northern Flickers that nest in New England do both.  Some remain here for the winter, while some fly further south and return next spring to their northern breeding grounds.

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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 Removing Fecal Sacs

7-4-19 fecal sac 1B0A1346Young birds defecate in little packages called fecal sacs. These structures serve several purposes, one being that having waste contained in a sac keeps the nest relatively clean. Often parents consume these sacs when their nestlings are small (when young the birds don’t completely digest the food they eat and fecal sacs may provide parents with a nutritional snack), but eventually the adults usually retrieve them and fly away from the nest before dropping them. (The young of some species of birds in open nests perch on the rim of the nest and defecate.) Two to five days before fledging, Pileated Woodpeckers stop removing their offsprings’ fecal sacs (perhaps as an incentive to depart the nest?).

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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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Pileated Woodpeckers Foraging For Last of Wild Grapes

12-17-18 pileated woodpecker and grapes IMG_7731

Carpenter Ants and wood-boring beetle larvae are the mainstay of the Pileated Woodpecker’s diet.  Long slivers of wood in trees and logs are removed in order to expose ant galleries, creating large rectangular excavations.  The woodpecker’s long, pointed, barbed tongue and its sticky saliva enable it to catch and extract ants from the ants’ tunnels.

While ants and beetle larvae are consumed year-round, fruits and nuts are eaten when available. A study that took place in the Northeast found seasonal shifts in primary food items: fruit in fall, Carpenter Ants in winter, wood-boring beetle larvae in early spring, and a variety of insects in summer.

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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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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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Woodpeckers Drumming

12-29-16-hairy-female-woodpecker-345

Non-vocal communication between woodpeckers has become apparent in the last week or so — hairy woodpeckers have started to hammer out bursts of steady staccato drum beats on nearby trees. Both male and female woodpeckers drum year round, but they do so most intensively from January to May, especially during the courtship and early nesting seasons which begin in March. Woodpeckers drum for a variety of reasons: defending territory, attracting a mate, maintaining contact with a mate, signaling readiness for copulation and summoning a mate from a distance. Woodpecker pairs also engage in duet drumming, which is thought to play a role in nest site selection and in promoting and maintaining the bond between mates.

If you are hearing but not seeing a woodpecker drumming, it is possible to identify the species by the pattern and pace of its drumming. According to ornithologist David Sibley, the drum of the Hairy Woodpecker is extremely fast and buzzing, with at least 25 taps per second, but has long pauses of 20 seconds or more between drums. The Downy Woodpecker drums at a slower rate, only about 15 taps per second, and drums frequently, often with pauses of only a few seconds between each drum. (Photo is of a female Hairy Woodpecker.)

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Red-bellied Woodpeckers Sunning

7-20-16 male red-bellied adult 173Red-bellied Woodpeckers have extended their breeding range northward and westward over the last 50 years and are now breeding in northern New England.  Many are year-round residents here, while some individuals move further south during particularly harsh winters.  This range extension allows for observations not possible even 10 or 20 years ago.

While watching a Red-bellied Woodpecker this summer, I witnessed behavior I had never observed before.  The bird flew repeatedly to the same tree branch, flattened itself on the branch with its body facing the sun and then fanned its wings out while cocking its head, raising its crown feathers, opening its beak and appearing to look at the sun.  This behavior is common enough to have a name – the woodpecker was “sunning” itself.  While preening, stretching and calling often takes place intermittently while the bird is engaged in sunning, it may also enter a stupor or state of lethargy.   (Thanks to Cindy Lawrence for photo op.)

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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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Yellow-bellied Sapsuckers Drilling Wells & Lapping Sap

4-26-16 yellow-bellied sapsucker 191

Yellow-bellied Sapsuckers have returned and in between sending their Morse code messages, are drilling into over 1,000 species of woody plants to obtain sap.  At this time of year, sap wells are drilled into xylem tissues (transport water and nutrients from roots to branches) to feed on sap that is moving upward; after deciduous species leaf out, sap wells tap phloem tissues (transport sugars and other nutrients made in the leaves to other parts of the tree).  Unlike sap drawn from the xylem which contains from 2-3% sugar, phloem sap may contain 20-30% sugar.

Sapsucker tongues have a fringe of hair-like projections along the edges which enable the sapsucker to lap up the sap that accumulates in a well (“saplapper” would be a more accurate name for these woodpeckers).  Recently a female sapsucker landed on the trunk of a nearby Sugar Maple and tapped eight wells.  She then spent the better part of the afternoon inserting her brush-like tongue into the wells and drinking the sap that collected.  The entire time she was drinking sap, she was constantly (8 times per hour) evacuating a stream of clear liquid (as opposed to the typical uric acid excreted by birds).  Apparently much of what goes in must come out.

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Pileated Woodpecker Droppings

11-12-15 pileated droppings 015Pileated Woodpeckers usually defecate frequently during the day at their foraging sites. As they pry off long slivers of wood to expose carpenter ant galleries, the wood chips pile up on the ground. A substantial pile usually indicates that the woodpecker has been working long enough at this site for there to be some droppings in the pile.

Pileated Woodpeckers eat ants, primarily carpenter, and beetle larvae throughout the year. Fruit and nuts are eaten when available. The primary food shifts seasonally, with fruit mainly in the fall, carpenter ants in the winter, wood-boring beetle larvae in early spring, and a variety of insects in the summer.

Like humans, birds excrete metabolic waste products, mainly nitrogen, which remains after food is broken down. Humans excrete waste nitrogen as urea in urine, which is diluted with water. Birds, needing to be as light as possible for efficient flight, do not have heavy, water-filled bladders. They excrete nitrogen as a chemical called uric acid in a concentrated form with no dilution necessary. The white outer coating of bird droppings is uric acid. The insides of the droppings are the actual feces, or the indigestible parts of a bird’s diet. A Pileated Woodpecker’s droppings at this time of year consist of bits of carpenter ant exoskeletons and a surprisingly small amount of wood fiber (see insert). Birds simultaneously evacuate uric acid and feces from an opening just under the tail called the cloaca or vent.

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Pileated Woodpecker Feeding Hole Embellishment

3-2-15  pileated horizontal lines 057Large rectangular excavations in trees, indicating Pileated Woodpecker feeding activity, are relatively common. These holes give the woodpecker access to carpenter ants living in galleries within the tree. What are not common are the horizontal lines radiating out from either side of the top rectangular Pileated Woodpecker feeding hole (and, more subtly, the bottom two holes) in the pictured tree.

Pileated Woodpeckers use methods other than drilling rectangular holes to locate insects – they glean branches, trunks and logs, peck bark and scale bark off of trees. But these lines are unusual, to say the least. If anyone is familiar with this pattern, and would care to explain the function of these horizontal lines, it would be greatly appreciated. After racking my brain and checking several resources, I cannot come up with a plausible explanation, though inevitably there has to be one, for no pileated woodpecker, or any other creature, is about to waste precious energy, especially in a winter as cold as this one. (Thanks to photographer, naturalist and keen-eyed John Snell (http://stilllearningtosee.com/about/) for finding and sharing this discovery with Naturally Curious.)

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Wood Drilling Adaptations

2-4-15  hairy woodpecker 072Woodpeckers have begun their courtship drumming and they continue to excavate trees for food. Both of these activities involve a woodpecker’s head striking a tree’s surface at speeds up to 13 – 15 mph, and continuing to do so at over 100 strokes per minute. To sustain this kind of blow against a tree, woodpeckers have a number of skull adaptations, including strong yet lightweight skulls and bills, a network of bony supports within their skull, extra calcification of the portion of the skull nearest the tip of the bill, cushioning cartilage joining the bones between the skull and the beak, shock-absorbing neck muscles and a brain that is packed very tightly into the brain cavity.

A woodpecker’s brain, however, isn’t the only part of its anatomy that is adapted for drilling wood. A woodpecker’s nostrils are narrow slits (not circular, as in many birds) and are covered with bristly feathers that prevent wood chips and dust from entering them. Special cells on the end of its bill are constantly replacing material lost due to drilling. This keeps the chisel-pointed bill strong and resilient, while allowing it to be sharpened with every blow. And finally, less than a second before a woodpecker’s bill contacts wood, a thickened nictitating membrane closes over its eyes, protecting them from flying wood chips. (Photo: male hairy woodpecker)

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Bark Scaling

12-11-12  bark scaling 024There are two main ways that woodpeckers and occasionally other birds remove bark in search of insects beneath it. One is bark sloughing, where a bird pries off the entire dead layer of bark on a tree (see NC post on 12/5/14). Another method of locating insect larvae that both woodpeckers and nuthatches employ is the removal of individual scales of bark. This is referred to as bark scaling. The pictured hairy woodpecker has removed much of the bark of a dead eastern hemlock using this method.

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Woodpeckers Bark Sloughing

woodpecker bark peeling IMG_0567Several species of woodpeckers search for wood-boring beetle larvae by removing the bark from a tree (in addition to drilling holes). This is referred to as bark sloughing. Some birds, such as nuthatches, remove only scales of bark, not the whole layer like woodpeckers, and this is referred to as scaling. After finding or creating an opening, a woodpecker repeatedly slips its pointed beak under loose bark, prying it off of the tree. It then uses its long, barb-tipped tongue to capture the exposed insects. Different woodpecker species tend to feed on either trunks or branches, and at different heights. Initially sloughing can resemble the work of porcupines, but close examination can reveal the marks of a beak, which are perpendicular to the trunk or limb, rather than the grooves left by a beaver’s incisors.

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Avian Toe Arrangment

3-17-14 mourning dove tracks 004As opposed to humans, who use the entire bottom of their feet for support, birds stand and walk only on the ball of their foot and with their toes. When you look at a bird’s leg, what appears to be its knee, bending backward instead of forward as it does in humans, is actually its heel.

Most birds have four toes, arranged differently according to the life style of the bird. Songbirds, as well as most other birds, have three toes pointing forward and one pointing back. Most woodpeckers, being active climbers, have two toes pointing in each direction, which provides added clinging support. The outer toe (of the three forward toes) of ospreys and owls is reversible, so that they can have two toes in back should they need to get a better grasp on slippery fish or other prey. Some birds that do a lot of running, such as sanderlings and most plovers, have only the three forward toes. (Photo: Mourning Dove tracks)

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White-tailed Deer Scavengers

deer carcass2  028According to NPR, each year Americans waste 33 million tons of food (and much of this ends up in landfills where it produces methane, a potent greenhouse gas). This situation is totally alien to that of other animals in the natural world, which seem to find a use for any and every organic particle. Great crested flycatchers incorporate shed snake skins into their nests, beavers build dams and lodges with branches they have eaten the bark off of, ermine line their nests with the fur and feathers of prey — the list goes on and on. When it comes to food, there is equally little waste. The carcasses of animals do not linger long, as almost every atom of their bodies is recycled. Fishers, coyotes, foxes, raccoons, opossums, bald eagles, hawks, woodpeckers, ravens, crows and many other animals make short work of a dead deer in winter. Come spring, if there’s anything left, the final clean-up crew consists of legions of turkey vultures, beetles, flies and bacteria, among others. How unfortunate we’ve strayed so far from a process that’s worked for so many for so long.

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Hairy and Downy Woodpecker Bills

12-31-13 woodpecker billsDistinguishing Hairy Woodpeckers (Picoides villosus) from their smaller relatives, Downy Woodpeckers (Picoides pubescens), can be challenging if you don’t have a chance to view both species at the same time. The easiest way to tell them apart is to note the relative size of their bills. The Hairy Woodpecker’s bill is proportionately much larger than the Downy Woodpecker’s – it’s almost as long as its head — whereas the Downy Woodpecker’s bill is not nearly as impressive. Although a Downy Woodpecker can’t drill or probe as deeply into trees as a Hairy Woodpecker, it does have at least one advantage due to its overall smaller size; it is light enough to balance on the stems of goldenrods, which usually aren’t strong enough to support Hairy Woodpeckers. It is here that Downy Woodpeckers drill for overwintering goldenrod fly larvae inside goldenrod ball galls – a popular winter snack for this species.

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Pileated Woodpecker Sign

12-26-13 pileated sign2 IMG_8246Pileated Woodpeckers typically make rectangular holes in trees in order to reach the carpenter ants that live in galleries they’ve created deep within a tree. While ants are high on a Pileated Woodpecker’s list of preferred food, wood-boring beetle larvae are not far behind. Sometimes the exertion of jackhammering isn’t necessary in order to reach insect larvae – removal of the outer bark is enough to expose tasty morsels.

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