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Black-backed Woodpecker

 

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Scientific Name: Picoides arcticus

Nest Type: Cavity

Nest Location: Snags, coniferous trees; 2-15'

Clutch Size: 2-6; avg. 4

Food: Insects

Foraging Guild: Bark gleaner

Black-backed Woodpeckers are permanent residents in the northeastern and north-central conifer forests of Minnesota. Their North American distribution extends across the entire boreal forest of Canada to southeastern Alaska and southward into the Rocky Mountains as far as northern California (National Geographic Society 1983). In Minnesota, irruptions have been known to occur in exceptional fall seasons, with birds recorded as far south as the Twin Cities area (Huber 1974, Janssen 1987).

Preferred habitats for this species are mature coniferous forests (Green and Niemi 1978). Specific habitat types include tamarack/spruce bogs, mature white cedar (Roberts 1932, Brewer et al. 1991, Robbins 1991), recently burned conifer stands (Niemi 1977, Brewer et al. 1991), and upland spruce, balsam, and pine (Roberts 1932, Niemi pers. obs.). Niemi and Hanowski (1984, 1992) did not find the species to be very abundant in the black spruce and tamarack forests of the Red Lake peatland during relatively extensive censuses from 1979 to 1981.

The Black-backed Woodpecker has been noted for its irregular irruptions which often last several years and are followed by long periods without irruptions (Yunick 1985). The irruptions seem to be due to various disturbances including fire, disease, and insect infestations such as spruce budworm outbreaks. During these events, populations of Black-backed Woodpeckers tend to increase because of the increase in wood-boring beetle larvae (see Yunick 1985 and references therein).

The species gleans bark-dwelling invertebrates by removing flakes of bark from dead or dying conifer trees which reveals wood-boring insect larvae that compose most of their diet along with caterpillars, ants, and other insects (Roberts 1932). Evidence of this type of feeding is quite noticeable as the freshly exposed wood tends to be light in color and easily seen.

Nesting occurs in a cavity that the birds excavates each season (Mayfield 1958, Gresser 1974), and (Ehrlich et al. 1988). Nests are usually in conifer trees (Roberts 1932, Kilham 1966), and (Cottrille 1974). However, much of the breeding biology of this species is not well known (Ehrlich et al. 1988).

Roberts (1932) speculated that this species had declined in Minnesota from population levels at the turn of the century. These declines were likely related with the loss of suitable, mature conifer forest habitat. Moreover, forest management practices which result in fire suppression and control of insect outbreaks and disease have likely reduced preferred nesting and feeding habitats and populations of these species. No data are available to detect a trend in the population since Roberts 1932 book on Minnesota birds was published. The Breeding Bird Survey of roadside counts showed no pattern of trend, but the species was only observed on three of 52 routes (Janssen 1990). In Wisconsin, Black-backed Woodpeckers were abundant winter visitors in the southeast portion in the mid-1800s (Krumlien and Holister 1951). Loss of conifer forests in southeastern Wisconsin likely is associated with the loss of the species from southern Wisconsin and Minnesota (Robbins 1991).

The species was classified as conifer-dependent, a species associated with mature forests, and a cavity-dependent species.