Black-backed Woodpecker Life History

Habitat

Habitat Forests

Black-backed Woodpeckers inhabit coniferous forests of northern North America and the western mountains. Key trees in these habitats include Douglas-fir, ponderosa pine, lodgepole pine, spruce, fir, hemlock, tamarack or larch, white-cedar, and sometimes aspen. Although the species does occur in unburned forest, it reaches its highest densities in recently burned areas, including not just coniferous forest but occasionally also burned or insect-infested deciduous forest. If burned areas are salvage-logged following the fire, it severely reduces usage by Black-backed Woodpeckers. Burned forests remain suitable for Black-backed Woodpeckers for about 8 years following the fire, coinciding with the decline of wood-boring insect populations. The species uses other habitats that contain abundant dead trees, including bark beetle outbreaks and wooded bogs, especially in areas without frequent wildfires. Black-backed Woodpeckers typically begin colonizing burned forests before the start of the next growing season following the fire. It’s not known exactly how the birds find these newly burned forests, but it may involve young birds dispersing away from the place where they hatched. These dispersing juveniles sometimes turn up in unexpected places, where appropriate habitat is absent, such as lakeshores or towns.

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Food

Food Insects

Black-backed Woodpeckers eat mainly the large larvae of wood-boring beetles in the families Cerambycidae (long-horned wood-borers) and Buprestidae (flat-headed wood-borers or jewel beetles). They also eat the much smaller larvae of bark beetles such as mountain pine beetles (family Curculionidae) and darkling beetles (family Tenebrionidae). The white-spotted sawyer, a long-horned beetle, is abundant in burned forests, and its larvae form a large part of the woodpecker’s diet in the boreal forest. Black-backed Woodpeckers forage mostly on trunks and large limbs of burned trees. They spend long periods working in a single spot, first pecking through the tree’s bark to find larvae just below the surface, or finding larval tunnels that extend deep into the wood. In this case the birds insert their long tongues into the tunnels, pulling out and flicking aside sawdust and insect frass until they can reach the grub, which is sometimes as long or longer than the bird’s bill. Because of the species’ strong association with wood-borers and burned trees, ornithologists consider it the most specialized forager among North America’s woodpeckers. On occasion, these woodpeckers also forage on fallen logs or on the ground.

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Nesting

Nest Placement

Nest Cavity

Black-backed Woodpeckers excavate nest cavities in spring, usually in a relatively small, dead tree in areas with a high density of relatively large trees. They occasionally nest in live trees. Nests are fairly low and usually on the main trunk, about 10–35 feet off the ground.

Nest Description

The male does most of the early excavation, and the female takes over as the nest hole nears completion. Nest holes have entrances about 1.8 inches in diameter, usually with a bevel or “doorstep” on the lower rim. The cavity itself is around 4 inches in diameter and 8 inches deep. The birds often leave wood chips in the bottom of the cavity. Pairs typically construct a new nest hole with each nesting attempt.

Nesting Facts
Clutch Size:2-6 eggs
Egg Length:0.9-1.0 in (2.23-2.59 cm)
Egg Width:0.7-0.8 in (1.75-2.02 cm)
Nestling Period:26-22 days
Egg Description:

White.

Condition at Hatching:

Naked and helpless.

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Behavior

Behavior Bark Forager

Black-backed Woodpeckers are highly mobile, often wandering widely in search of a burned forest for nesting. Once they have found such a site, they continue to nest in it for several years until insect populations decline. Territory sizes can be small or very large depending on available food, and in some areas Black-backed and other woodpecker species can nest within a few hundred feet of each other. Black-backed Woodpeckers use a variety of calls and postures during the breeding season to court mates and to warn rivals, and in many cases the same postures may function in both courtship and conflict. Among the displays are raising the bill, raising the crest, swinging the head side to side, spreading the tail, and spreading the wings. Both male and female may exhibit these behaviors, sometimes together against an intruder. Males also use a remarkable mothlike flight (with slow wingbeats) to assert dominance over a rival, and this display sometimes escalates to a physical attack with feet, wings, and bill. Both male and female incubate the eggs, and both feed the young. Mated pairs sometimes remain together during the nonbreeding season and breed again in the following season.

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Conservation

Conservation Low Concern

The North American Breeding Bird Survey estimates that populations of Black-backed Woodpecker have been roughly stable between 1966 and 2015, although this species’ tendency to move among ephemeral habitats makes tracking its numbers difficult. Partners in Flight estimates a global breeding population of 1.7 million and rates the species an 8 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. Black-backed Woodpecker populations are vulnerable to many widespread forestry practices—but especially fire suppression and postfire salvage logging—which reduce habitat available for foraging and nesting.

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Credits

Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2017). The North American Breeding Bird Survey, Results and Analysis 1966–2015. Version 2.07.2017. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, USA.

Tremblay, Junior A., Rita D. Dixon, Victoria A. Saab, Peter Pyle and Michael A. Patten. (2016). Black-backed Woodpecker (Picoides arcticus), version 3.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

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