Hairy Woodpecker

Permanent resident; a common species during the Minnesota Breeding Bird Atlas (MNBBA).

Distributed across central Alaska and Canada south of the tree line, and throughout most of the United States into Central America. It is absent from pockets in the northwestern United States and from large regions in the arid Southwest. Sparsely distributed throughout its range, some of the highest breeding densities occur along the West Coast, in the Great Lakes region, and in New England and the Maritime Provinces (Figure 1).

Assigned a Continental Concern Score of 6/20 by Partners in Flight.

Permanent resident; a northern subspecies that occurs in Canada migrates south into northern and central Minnesota from early October through late April.

Feeds largely on wood-boring beetles and bark beetles as well as ants and caterpillars and some fruits and seeds. A bark driller and gleaner.

Primary cavity nester.

The Hairy Woodpecker has long been recognized as a common, year-round resident throughout Minnesota. Not only is it common throughout the extensively forested regions of northern Minnesota, it can be found wherever small woodlands are present, including the extensively cultivated agricultural counties of western Minnesota. As Roberts (1932) noted nearly a century ago, it even is found residing in city parks and neighborhoods of some of the state’s most densely populated areas. Nevertheless, he thought it might demonstrate “a preference for tamarack and spruce swamps and the wilder stretches of woodlands.” Despite its wide distribution, confirmed nesting records (nests with young) were available from only 2 counties (Hennepin and Isanti) and inferred nesting records (nest excavation or recently fledged young) were available from 3 counties (Aitkin, Goodhue, and Sherburne).

Neither Green and Janssen (1975) nor Janssen (1987) had much to add to Roberts’s original account of the species’ status and distribution. As they did for this species’ diminutive look-alike the Downy Woodpecker, all three authors noted the presence of two subspecies in the state. Minnesota’s breeding population is assigned to the eastern subspecies, Picoides villosus villosus. A larger and oftentimes whiter subspecies, P. v. septentrionalis, occurs north and northwest of Minnesota. Although the eastern subspecies is a permanent resident, the northern subspecies is known to wander during the winter months. Its movements are sporadic and unpredictable, but birds identified as P. v. septentrionalis have been reported in northern and central Minnesota from early October through late April since the time of Roberts’s observations (Roberts 1932; Janssen 1987; Jackson et al. 2002). Roberts even described it as “an occasional summer resident in the extreme northern part of the state.” Green and Janssen (1975) cautioned, however, that some local breeding individuals show characteristics that are intermediate between the two subspecies, making it difficult to accurately delineate the seasonal movements of the northern subspecies. Apart from the detailed account of the two subspecies in Roberts (1932), the issue has received little attention.

Janssen’s 1987 updated account on the species noted that since 1970, nesting had been confirmed in 31 counties scattered throughout the state. In 1998, Hertzel and Janssen added 9 counties to the list. During the course of their statewide survey work, field staff with the Minnesota Biological Survey documented a similar statewide distribution for the species (Minnesota Department of Natural Resources 2016).

During the MNBBA, observers reported a total of 2,460 Hairy Woodpecker records in 35.4% (1,680/4,740) of the surveyed atlas blocks and in 44.5% (1,041/2,337) of the priority blocks. Breeding evidence was documented in 5.7% (269) of the surveyed blocks (Figures 2 and 3; Table 1). Observers reported Hairy Woodpeckers in all 87 Minnesota counties and confirmed breeding in 62 counties. Thirty of the counties where breeding was confirmed were additions to the list published by Hertzel and Janssen in 1998. Four of the confirmed reports were from 3 blocks that straddled 2 counties each along the Minnesota River valley: Redwood/Renville, Brown/Renville, and Brown/Nicollet. The birds were most abundant in the Laurentian Mixed Forest and Eastern Broadleaf Forest Provinces. The Downy Woodpecker, with a total of 2,724 records reported from 1,730 atlas blocks, was slightly more common than the Hairy Woodpecker. The Hairy Woodpecker was the fourth most abundant woodpecker following the Northern Flicker, the Yellow-bellied Sapsucker, and the Downy Woodpecker.

Remarkably little has changed for the Hairy Woodpecker in the past 100 years. It is likely more abundant in areas of western Minnesota, as shade trees in the small towns, cities, and farm shelterbelts of the agricultural landscape have matured. The same is true throughout the species’ breeding range. Although there have been no significant large-scale changes in its distribution, the loss of mature forests and the intensification of agricultural practices in the eastern United States have likely led to local declines, while in areas of the Northeast, forest succession on abandoned farmland has created new habitat opportunities. The same is true in the Great Plains and arid southwestern states, where irrigation and tree plantings likely have facilitated local population increases (Jackson et al. 2002).

*Note that the definition of confirmed nesting of a species is different for Breeding Bird Atlas projects, including the definition used by the Minnesota Breeding Bird Atlas, compared with a more restrictive definition used by the Minnesota Ornithologists’ Union. For details see the Data Methods Section.

Like its near relative the Downy Woodpecker, the Hairy Woodpecker is cosmopolitan in its selection of suitable habitat. Typically associated with mature deciduous and mixed deciduous forests (both upland and lowland), it is likely to be found anywhere where large trees prevail, including small woodlots, city parks, residential areas, cemeteries, and even recent burns (Danz et al. 2007; Figure 4). Generally, however, Hairy Woodpeckers are most frequently reported in mature, undisturbed habitats rather in disturbed, successional habitats (Noon et al. 1979). Where timber harvests have been managed to retain snags, these residual trees may be used as perches or as foraging sites but are seldom used for nesting cavities (Loose and Anderson 1995). At least one study suggested the species required a minimum of 4 ha of wooded habitat for nesting (Robbins 1979). However, the woodpecker’s sensitivity to the size of a forest stand and the composition of the forest landscape has not been well studied.

Data gathered from MNBBA point counts demonstrate the diversity of habitats used by Hairy Woodpeckers, but demonstrate a strong preference for upland coniferous forests, peatlands (bogs), lowland coniferous forests, and northern mixed forests (Figure 5). During a long-term monitoring program on the four national forests in northern Minnesota and Wisconsin, Hairy Woodpeckers were found in virtually every forest habitat and did not demonstrate an overwhelming preference for any particular cover type (Niemi et al. 2016).

Because the Hairy Woodpecker is a primary cavity nester, the limiting factor in habitat selection is the availability of suitable nest trees that are of sufficient size and have an adequate amount of decay for excavation. Hairy Woodpeckers prefer nesting in mature deciduous trees, frequently selecting a live tree with fungal heartrot. Their large, chisel-like bill provides them with some flexibility to select trees that are relatively healthy with harder wood (Runde and Capen 1987).The cavity itself may be excavated in the main trunk or on the underside of a dead limb.

Data gathered by the federal Breeding Bird Survey (BBS) have been used to generate a 2016 global breeding population estimate of 8.5 million breeding adults (Rosenberg et al. 2016). Minnesota was estimated to support approximately 2% of the continental population in 2013 (Partners in Flight Science Committee 2013). When that percentage is applied to the 2016 population estimate, it yields a statewide population estimate of nearly 170,000 breeding adults.

Although the Hairy Woodpecker is widely distributed, populations generally do not reach high densities anywhere within its breeding range. Evans and Conner (1979) estimated that across eastern North America Hairy Woodpeckers averaged 12.5 pairs/km², but little quantitative data are generally available. In northern Minnesota, population density estimates ranged from 4.35 detections per 100-10 minute unlimited distance point counts on the Superior National Forest to 4.51 detections on the Chippewa National Forest. Breeding densities were higher in northern Wisconsin, where they ranged from 5.28 detections per 100-10 minute point counts on the Nicolet National Forest to 6.33 on the Chequamegon National Forest (Niemi et al. 2016). Low as they may be, the breeding densities found in portions of northern Minnesota and Wisconsin are among the highest found in North America (Figure 1).

Because of their relatively low abundance along BBS routes throughout North America (invariably an average of less than 1 bird is observed on BBS routes each year), statistical analyses of population trends lack precision, both at the national level and within most states. One of the few ecological regions where the trend line is statistically robust is the Boreal Hardwood Transition region, which includes the Laurentian Mixed Forest Province of Minnesota. Given that the latter is the primary core of the species’ breeding range in the state, the regional trend is a good proxy for the statewide trend. Since 1966, Hairy Woodpeckers have demonstrated an average annual increase of 1.72% per year in the Boreal Hardwood Transition region (Figure 6). Indeed, range-wide populations are estimated to have increased by 54% since 1970 (Rosenberg et al. 2016). Although the Minnesota data lack statistical precision, they also suggest an increasing population.

On Minnesota’s two national forests, where birds have been monitored for over two decades, the Hairy Woodpecker demonstrated a relatively stable but slightly increasing population trend on both the Chippewa and Superior National Forests from 1995 to 2016; as a result, the combined regional trend is also increasing (Figure 7).

An examination of the species’ regional population trends revealed a more complex picture. By and large, populations across the boreal hardwood forests of New England, southeastern Canada, and the Great Lakes are increasing, while populations in many regions of the southeastern United States are declining. Farther west, populations in British Columbia and the Rockies are increasing, while populations along the Pacific coast are declining (Sauer et al. 2017). Factors often cited as responsible for local declines were habitat fragmentation, loss of mature and old-growth forests, and competition for nesting cavities with European Starlings and House Sparrows. The latter species can be quite aggressive in securing a cavity once the woodpecker has completed its excavation (Jackson et al. 2002; Bent 1939).

A widely distributed species with stable to increasing populations, the Hairy Woodpecker has been assigned a relatively low Continental Concern Score of 6/20 by Partners in Flight (Rosenberg et al. 2016).

Specific forest management recommendations focus on the need to protect stands with large, mature hardwood trees (Danz et al. 2007). One study in the northeastern United States recommended managing forest stands with 160–200 snags per 40 ha with an average dbh of 25–35 cm and at least 6–12 m in height (Evans and Conner 1979). In the Pacific Northwest, researchers recommended managing approximately 45% of the landscape in stands that are older than 40 years, and 30% of the landscape in stands that are older than 60 years to insure that adequate nesting habitat is available (Ripper et al. 2007).

Warming temperatures may pose a threat to Hairy Woodpecker populations. An extensive analysis of the potential impacts of climate change on 588 North American birds predicted that the species could lose 78% of its current range by the year 2080, forcing the bird northward if suitable habitat replaces today’s tundra (Langham et al. 2015; National Audubon Society 2016). As a result of the analysis, the species was classified as “climate threatened”. In the short-term, however, the Hairy Woodpecker has a secure and stable future in Minnesota.