One of the most easily recognized birds in eastern North America, this aptly named species is perhaps the best example of a sexually monomorphic woodpecker, with adult males and females being indistinguishable in the field. The Red-headed Woodpecker is a highly omnivorous species, the most expert and persistent flycatcher in its family, and one of only four woodpeckers in the world that commonly stores food.
Over the last 200 years, this species has undergone periods of great abundance and scarcity, when it appeared to be on the verge of extinction. Ornithologists in the early 1900s were baffled by its erratic occurrence. Movements during the nonbreeding season were historically influenced by nut crops in formerly extensive American beech (Fagus grandifolia) forests, and contemporary movements are associated with large-scale variation in the abundance of acorns. Breeding populations may have benefited from the demise of American chestnut (Castanea dentata) and American elm (Ulmus americana) trees in the eastern deciduous forest, but may have been adversely affected by the disappearance of a formerly abundant grasshopper in the Midwest. More recently, Red-headed Woodpecker populations have declined in most regions that support the bird, and the species is now listed as Threatened in Canada and several U.S. states.
This brilliantly colored bird has had a variety of colorful common names, such as white-shirt, half-a-shirt, shirt-tail bird, tricolored woodpecker, jellycoat, flag bird, and the flying checker-board. The Red-headed Woodpecker inspired Alexander Wilson to become an ornithologist ( Forbush 1927b ), was one of the first birds that Ludlow Griscom learned to identify ( Davis 1994a ), and caught the fancy of Lawrence Kilham, who went on to a distinguished career studying woodpeckers ( Kilham 1983a ). It was a war symbol of Cherokee Indians, and its head was used as a battle ornament, particularly by Plains tribes ( Witthoft 1946 ). This was the woodpecker whose head Hiawatha dipped in the blood of Pearl Feather in Longfellow's poem ( Taverner 1953 ).
The conspicuousness of this species has led to a plethora of short notes and general accounts, with mostly anecdotal information about its biology. Many aspects of its behavior and ecology were first elucidated by the long-term observations of Lawrence Kilham (summarized in Kilham 1983a ). Quantitative breeding information was first published several decades ago ( Reller 1972 , Jackson 1976a ), followed by studies of breeding habitat use and nest success ( Rodewald et al. 2005 , Vierling and Lentile 2006 , King et al. 2007b , Frei et al. 2013 , Hudson and Bollinger 2013 ). However, there remains little information regarding nesting success, and the growth and development of nestlings, owing to the species' propensity to nest in inaccessible locations (i.e., tall snags or dead branches). Further, few individuals have been color-banded, so little is known about differences in behavior or ecology of the sexes.
As with many cavity-nesting species, Red-headed Woodpecker may compete intra- and inter-specifically for nesting sites, especially in areas where nest sites are scarce. Aggressive interactions with the non-native European Starling (Sturnus vulgaris) have been reported. The likelihood of competition for nest sites contributing to declines of this woodpecker has varying degrees of support in the literature, perhaps owing to regional differences in breeding phenology, habitat structure, or other ecological factors.
Although the Red-headed Woodpecker is a charismatic species, their nesting habits and population fluctuations make them a challenge to study. This, in part, may explain why we know less about their natural history relative to other North American woodpeckers. Increasing our understanding of Red-headed Woodpecker biology, especially with respect to factors that regulate their populations, is needed to inform ongoing conservation efforts and recovery planning for this strongly declining species.