Downy Woodpecker

Woodpeckers are a family of birds sharing several characteristics that separate them from other avian families. Most of the special features of their anatomy are associated with the ability to excavate wood. The straight,chisel-shaped bill is formed of strong bone overlain with a hard covering and is quite broad at the nostrils in order to spread the force of pecking. A covering of feathers over the nostrils keeps out pieces of wood and wood powder. The pelvic bones are wide, allowing for attachment of muscles strong enough to move and hold the tail, which is so important for climbing. Another special anatomical trait of woodpeckers is the long, barbed tongue that searches crevices and cracks for food. The salivary glands produce a sticky, glue-like substance that coats the tongue and, along with the barbs, makes the tongue an efficient device for capturing insects.

There are 198 species of woodpeckers found throughout the world, 13 of them occurring in Canada. The smallest and perhaps most familiar of the species found in Canada is the Downy Woodpecker Picoides pubescens. It is similar in appearance to the larger Hairy Woodpecker Picoides villosus. Both are black and white with a broad white stripe down the back from the shoulders to the rump. The wings are checkered in a black and white pattern that shows through on the wings' undersides, and the breast and flanks are white. The crown of the head is black; cheeks and necks are adorned by black and white lines. The males of both species have a small scarlet patch, like a red pompon, at the back of the crown.

Although they look very much alike, the Downy and the Hairy Woodpecker have distinguishing characteristics. The Downy's outer tail feathers are not all white as are the Hairy Woodpecker's, but are barred with black. The Downy is about 6cm smaller than the Hairy, measuring only 15– 18cm from the tip of its bill to the tip of its tail. And the Downy's bill is shorter than its head, whereas the Hairy's bill is as long as or longer than its head length.

Male and female Downy Woodpeckers are basically the same size, weighing in the range of 22– 33g. The females have a longer tail and slightly shorter bill.

Like most woodpeckers, the Downy is a climber. Its short legs and two toes pointing forwards and two backwards on each foot give the bird an excellent grip for climbing. It climbs by propping its stiff, sharply pointed tail feathers against the support while shifting its leghold. With its body close to the trunk or branch and its head bobbing, the bird "hitches" upwards, backs down spiralling, and nimbly darts sideways at incredible speed.

Distribution

The Downy Woodpecker occurs over the greater part of the North American continent, from the Gulf states northwards. In Canada in the northernmost part of its range, it is found from Newfoundland across to James Bay, the northern Prairie Provinces, the southern Mackenzie District of the Northwest Territories, northern British Columbia, and the Yukon. Downys in the northern parts of the range migrate southward in the winter, but these migrations are somewhat irregular, depending on the available food supplies.

Habitat

Woodpeckers live where trees grow. The Downy Woodpecker is at home in a variety of wooded areas across its range, in the northern mixed forests and in the deciduous (broad-leaved) forests farther south, in woodlots and parklands, in orchards, and even in the parks and avenues of suburb, town and city. It prefers places where broad-leaved trees, such as poplars, birches and ashes, let in the light among the evergreens. Forest edges and areas around openings in the denser forests are also favoured places. In the western part of its range it can be found in alder and willow growth. The Downy shares these habitats with other kinds of woodpeckers, but there are differences in their selection of nest sites and in their choice of food. Each species thus occupies its own niche in the environment.

Breeding

Downy Woodpecker pairs often return to the same nesting area of approximately 2 ha every year of their adult life. Male and female Downys sometimes occupy separate sleeping holes in the trunks of trees, and they may even select the same sleeping holes they had excavated in a former season.

As early as February or March a Downy Woodpecker pair indicate occupation of their nesting site by flying around patrolling it and by drumming short, fast tattoos with their bills on dry twigs or other resonant objects scattered around the territory. The drumming serves as a means of communication between the members of the pair and informs other Downys of their occupation of the land. Downys also have a variety of calls. They utter a "tick, tchick, tcherrick," and both male and female add a sharp whinnying call during the nesting season.

During the breeding season Downy Woodpeckers defend their territory against trespassers of their species. Encounters with intruders result in hostile displays: the opponents parade in front of each other in threatening poses, bills gaping, wings raised and fully opened, the birds twisting and turning like small windmills. The Downy male engages the male trespassers and the female the females, while their respective partners look on. These demonstrations may go on for several hours but seldom end in actual fighting. Usually the intruder is chased away or simply disappears.

After establishing their territory the Downy pair look for a suitable tree in which to excavate their nest cavity. They are especially attracted to dead trees or stubs dotted with old holes from former nestings. They may start several holes in different trees before the final choice is made, usually by the female. The entrance hole may be anywhere from 1.5 to 18.0m above the ground, but is usually from 3.6 to 9.0m.

The pair require about two or three weeks to excavate their nest hole, which has the form of a flask 12– 15cm wide and about 20– 30cm deep. The entrance is through a short narrow neck at the top.

The male does most of the drilling. He spends nearly half of the daylight hours each day working on the hole in average sessions of about 20 minutes, resting and feeding in between. First he chisels out the passage, making it just wide enough for himself and his mate to squeeze through. Laboriously he taps and digs out the walls of the cavity, widening and deepening the room inside and throwing the loose chips out over his shoulder. When the hole is deep enough to allow him to turn around inside, he brings the chips out in his bill and scatters them with a shake of the head. Henceforth he usually sleeps in the cavity at night.

The female occupies herself flying around, feeding, and chasing intruders. When the nest hole nears completion, she becomes more interested in it and begins to work on it diligently. The pair devote most of their free time to courtship involving calling and drumming, pursuits and displays.

The female Downy Woodpecker usually lays four or five white eggs and occasionally six or seven. During the egg-laying, male and female take turns guarding the nest by sitting in the doorway.

After incubation of the eggs starts, the birds take turns warming them during the day in shifts lasting from 15 to 30 minutes. Most change-overs take place directly and immediately at the nest. At night the male remains on the eggs alone while the female sleeps elsewhere. In this manner, the eggs are covered nearly all of the time during the Downy Woodpecker's 12-day incubation period.

The young

When the young woodpeckers hatch, they are tiny helpless creatures, almost naked, sprawled at the bottom of the cavity. For a few days the parents warm the nestlings as they did the eggs and occasionally bring them small insects for food.

As the nestlings grow, the parents gradually stop brooding and spend more time collecting food for their young. When the parent arrives with food in the bill there is a swell in the nestlings' chippering noises from within the nest. The parent dives headfirst into the cavity and touches the swollen corner of a nestling's mouth with its bill. As the mouth springs open, the parent pushes the meal down the nestling's throat. And while the nestling subsides, the parent picks up a dropping and flies away with it.

Thus the nestlings are fed and their nest is kept clean until they are 17 or 18 days old, when they are almost fully grown. They look like their parents, except that the crowns of the young males are tinted red or rust-red or pinkish, and those of the females are striped or dotted with white. The young ones are now able to crawl up the walls of the cavity and take turns sitting in the doorway, looking out. To meet the nestlings' increasing demands for food, the parents bring large meals about every three minutes. Each of four nestlings is therefore fed four or five times in the hour.

As the time approaches for the young to leave the nest the parents slow down the feedings, making the nestlings livelier and hungrier. The one in the doorway pops in and out with great vigour and calls loudly, but is in no hurry. Almost a day passes before the fledgling, now as large as its parents and spotlessly clean, pops out far enough to spread the untried wings. Once outside it is able to fly quite a distance before it achieves a safe landing.

When the fledglings are all out, they hide among the green leaves in the tall trees and call for the parents to come and feed them. Within a week they begin following the parents, begging for food with sharp calls and flapping wings. At the age of three or four weeks the young birds are fully capable of looking after themselves. It is at this stage in the life cycle that mortality is greatest, when the young are out of the nest and no longer protected by the vigilance of their parents.

Moult

The adult birds begin to moult their worn and dirty plumage while the young are still in the nest. The strong, central pair of tail feathers is moulted only after all the other tail feathers have been replaced. This ensures that the woodpecker's climbing ability is not hampered during the moulting period. The complete moult takes about two months, during which time each bird keeps much to itself, resting and feeding. When the moult is over in September, the Downy Woodpecker emerges with the white part of its fresh winter plumage showing a faintly yellow tinge that eventually is lost by wear.

The young Downy Woodpeckers also shed their juvenile plumages. Their moult starts in late summer and ends in full adult plumage. Their crowns are jet black, and at the back of the head the young males wear the bright red spot of the adult.

Food and feeding

In the spring and summer the Downy Woodpecker feeds on free-flying and hidden insect life, as it becomes available. After the young hatch, the need to select food suitable for the nestlings at various stages of growth and gradually to increase the speed of the feedings compels the Downy Woodpecker to seek larger and more easily caught prey, such as caterpillars, mayflies, and moths. It also takes small wild fruits in season.

After the nesting season, the Downy Woodpecker resumes its specialized feeding habits. It hunts down myriads of small insects and larvae that infest trees and lie hidden in cracks and crannies along branchlets,twigs, and down the trunk. The Downy's small size enables it to hunt along the upper branches of trees, while the larger heavier woodpecker species concentrate on more solid areas such as the trunk. Unlike some other species, such as the Red-headed Woodpecker, Downy Woodpeckers do not cache food for winter. During the winter a pair of Downy Woodpeckers may do a thorough job of ridding an infested tree of tiny scale insects. With its sharp bill boring small round holes or prying open the insects' hiding places, the woodpecker fetches out its food with its long agile tongue. Often the birds spend most of the daylight hours going over areas of good yield in the same trees, until they retire just before sunset, each to its own sleeping hole in the trunk of a tree.

A Downy Woodpecker feeding

Enemies

The woodpecker's first response to danger is to use a tree trunk or branch as a shield. Many a Downy Woodpecker has saved itself from the grasping talons of a hawk or the claws and bill of a shrike by dodging swiftly sideways behind the trunk of a tree.

Nestlings raised in holes are, of course, much safer than those in open nests. The narrow entrance to the Downy Woodpecker's nest, hewn to size, protects both the adults and the young from practically all predators except snakes. Even a squirrel, scratching and gnawing at the soft wood to get at the fledglings within, has little chance of getting past the watchful defender sitting in the passage way, its awl-like beak on the ready. But, if a Downy is caught at night behind a rotting doorway by some tree-climbing marauder, its fate is sealed.

From a human viewpoint, few wild birds have a record as irreproachable as that of the Downy Woodpecker. Its sober ways and its pest-killing activities merit our respect and attention.

Reading list

• Godfrey, W.E. 1986. The birds of Canada. Rev. ed. National Museums of Canada, Ottawa. 595 pp.
• Grier, K. 1985. Downy Woodpecker. Grolier, Toronto. 47 pp.
• Kilham, L. 1983. Life history studies of woodpeckers of eastern North America. Cambridge University,Cambridge, Mass. 240 pp.
• Lawrence, L. de K. 1968. A comparative life-history study of four species of woodpeckers. Ornithological Monograph No. 5, American Ornithologists' Union.
• Short, L.L. 1982. Woodpeckers of the world. Monograph Series No. 4, Delaware Museum of Natural History. Weidner Associates Inc., New Jersey. 676 pp.

	Canadian Wildlife Service - Hinterland Who's Who series Reproduced with permission of the Minister of Public Works and Government Services Canada, 1999. Copyright © 1999 Environment Canada. All rights reserved. Last update: 19 January 1999