Why are Red-headed Woodpeckers disappearing?
Red-headed Woodpeckers were once a common species throughout most of their range. After the initial arrival of Europeans, Red-headed Woodpeckers benefitted from the large-scale land clearing in the 18th and 19th centuries. As dense forests were made patchier and more open, this created more habitat for the species. But at the same time, by the early 20th centuries the near complete destructions of the extensive mature beech and oak forests started a precipitous decline in Red-headed Woodpeckers. They depended on these forests both to breed in but especially for the rich supply of beechnuts and acorns to feed them throughout the winter.
The Breeding Bird Survey (BBS) is a large-scale survey that monitors the population trends for birds in North America. Since its inception in 1966, Red-headed Woodpeckers have undergone a significant decline of 2.6%/year between 1966-2005, corresponding to an overall decline of 66% in roughly 40 years.
Concerns over the species declines have been slower than that for other species. This may be in part due to the cyclical nature of the species abundance. It appears that there has always been 'high' and 'low' years of Red-headed Woodpecker. The most likely explanation for this pattern is found in the Red-headed Woodpecker's winter diet. The hard mast (tree nuts) that they depend upon also has cycles of high and low production. Thus, it seems that the Red-headed Woodpeckers may follow the same patterns; that winters of plentiful food more birds survive and produce lots of young birds the next year and other years some may go hungry in winter.
*USA data only
Annual index of abdundance for Red-headed Woodpecker between 1970-2009 in Ontario according to the Breeding Bird Survey. Environment Canada, 2010
In Canada, the decline is even steeper with an estimated 3.4%/year decline from 1968 - 2005, with a total ~70% decline over the time period.
Although there is little historical data on Red-headed Woodpecker numbers in Ontario, this species was considered fairly abundant in the southern part of the province. Today, Red-headed Woodpecker are suffering one of the largest declines across it's range. And with >60% of the population declining over the last two decades, the species is swiftly disappearing from Ontario.
Red-headed Woodpecker Ontario Breeding Bird Atlas 1981-1985
Red-headed Woodpecker Ontario Breeding Bird Atlas 2001-2005
In Ontario, as portrayed in the Ontario Breeding Bird Atlas maps above, Red-headed Woodpeckers were still quite common in the south and central part of the province in the 1980s. But just 2 decades later they are found in far fewer places.
Potential threats to Red-headed Woodpecker
Several factors have been suggested for the more recent declines of Red-headed Woodpeckers, including: the loss of snags used for nest and roost sites due to deadwood removal in urban areas and fire-wood cutting, clear-cutting, fire suppression and agricultural intensification in rural areas, collision with motor vehicles, pesticide and chemical exposure and possible interference competition with other cavity nesters such as European Starlings.
Habitat loss and fragmentation is one of, if not the, major factor leading to species declines and endangerment worldwide. Globally, 83% of the land’s surface has been influenced by human activity. In Canada, the area predominantly modified by human presence is in the southern part, of the country which also includes the area with the mildest climate, highest habitat heterogeneity, and greatest species richness.
The majority of at-risk species in Canada, including the Red-headed Woodpecker, are in the prairies and mixed wood plain ecotones, the areas best suited for and most altered by agricultural activities. Opportunities for species at risk recovery in these areas are severely limited under the Species at Risk Act, whose power lies within the sphere of public land management. Therefore, the recovery of species at risk in Canada, and likely many other countries, will be reliant on the cooperation of private landowners, especially on farmlands.
The loss of remaining deciduous forests, pastures and savannas to urban sprawl and agricultural monocrops are likely a serious threat to Red-headed Woodpeckers across their range.
Photo by Barbara Frei
Loss of dead wood?
Photo by Sophie Gibbs
Dead, dying and downed trees are natural products of forest dynamics and are the results of natural stand aging processes, diseases and disturbances. Dead wood, whether standing (dead branches, snags and stubs) or fallen (logs) provide habitat for animals, serve as nursery beds for young seedlings and store nutrients to be later released back into the ecosystem.
Woodpeckers are tied closely to naturally dynamic forests, especially the dead wood common therein. Dead wood is an important forest resource to woodpecker species as: (1) almost all woodpeckers excavate nest cavities in dead wood and (2) many woodpeckers feed at least in part on saprophytic insects.
The use of standing dead wood by woodpeckers for nesting activities depends on two important factors: (1) the dead wood’s decay stage, and (2) the seral stage of the surrounding stand. Both these factors are temporary and, as such, dead wood structure and function may change over time. Most woodpecker species nest preferentially in live trees with decay or recently dead trees.
Woodpecker species are different physiologically, some such as the Hairy Woodpecker and the Pileated Woodpecker are strong primary excavators and typically excavate harder wood of a low decay class. In contrast, weaker primary excavators such as Northern Flickers, Red-headed Woodpeckers and Downy Woodpeckers typically excavate softer wood of high decay class. As decay progresses, dead wood becomes unavailable to woodpeckers as structural composition weakens and soon transitions to fallen dead wood. As the stand which the dead wood is within ages or undergoes disturbance, the dead wood is available for cavity nesters.
Competition for nest sites with other species?
With the limited supply of habitat and dead wood within the habitats for woodpeckers to excavate nesting cavities on a yearly basis, Red-headed Woodpeckers may not be the only species searching for a nesting site. Red-headed Woodpeckers are known to compete with other cavity nesting species, such as Red-bellied Woodpeckers, Northern Flickers and European Starlings for both nest sites and nest cavities. Most of these are anectodal reports but there has been some studies done in southern United States. European Starlings are still considered a major threat by both the Ontario Landbird Conservation Plan and the MNR/ROM species at risk website. Findings from last years work in this project suggest that this may only be the case in urban areas with high densities of starlings. Further work on this aspect is important to ensure that correct information is available for public education and decision making.
European Starlings beside usurped cavity in Cobourg, Ontario
Photo by Barbara Frei
Red-headed Woodpecker with a winged insect returning to nest
Photo by Ed Post
During the summer when the Red-headed Woodpecker is present in Ontario, it is thought to heavily feeds on aerial insects as well as nuts and berries. Unfortunately there is little actual information on what Red-headed Woodpecker do eat as the only study was performed in the southern U.S. a century ago (Beal 1911). There is strong evidence that a majority of aerial insect eating birds are declining steadily in Canada, including Ontario (McCracken 2008). Several factors may be responsible, including land use changes, climate change and increased pollution (McCracken 2008). Understanding Red-headed Woodpecker feeding habitats and the amount of their choice food in the habitat may have serious implications for both understanding the possible threat to their food supply and the threat to all aerial insect eaters including other species at risk in Ontario such as Chimney Swift, Common Nighthawk, and Olive-sided Flycatchers.