Red-headed woodpecker (Melanerpes erythrocephalus) COSEWIC assessment and status report: chapter 6

Biology

General

Although many recent studies have focused on the use of habitat by communities of excavating bird species, including the Red-headed Woodpecker, there has been no in-depth study of a specific population, and many aspects of the ecology of this species have yet to be discovered (Smith et al. 2000).

Reproduction

The Red-headed Woodpecker is monogamous (Smith et al. 2000). The age of sexual maturity is one year (Belson 1998) and the generation time is estimated at 3 to 5 years (according to the maximum age of 9 years (Clapp et al. 1983) and age of maturity). Nests are usually excavated by males in large snags (> 31 cm) or in dead branches of live trees at a height generally exceeding 7 m and in stumps at least 11 m in height (Smith et al. 2000). 

Incubation occurs between May and June, depending on the location (Peck and James 1983). Typically a single brood is reared per season, but a second brood is regularly raised in the southern part of its range (Ingold 1987; Smith et al. 2000). Throughout its breeding range, clutch size ranges from three to seven eggs, with an average of four (Short 1982; Peck and James 1983; Godfrey 1986; Smith et al. 2000). Both sexes incubate the eggs. Incubation generally lasts 12 to 14 days (Short 1982; Smith et al. 2000). The young hatch asynchronously and remain in the nest for 27 to 30 days, during which time they are tended by both parents (Jackson 1976; Smith et al. 2000). The average number of fledglings is 2.1 for a first attempt and 2.3 for a second (Ingold 1989). The fledglings are dependent on their parents for about 25 days after leaving the nest (Jackson 1976; Smith et al. 2000).

Survival

Martin (1995) reports an annual adult survival rate of 62%. The winter mortality rate is reported to be 7% (Doherty et al. 1996). Nesting success varies from 80% (n = 59 nests with at least 1 fledgling) in Mississippi (Ingold 1989) to 48.4% (n = 33 nests) in Arkansas (Withgott 1994).

Dispersal/migration

Only Red-headed Woodpecker populations from the northern and western parts of North America make fall migrations. The abundance and distribution of acorns and beechnuts in regions further south are believed to influence the start of migration and the selection of wintering sites (Smith and Scarlett 1987).

The Red-headed Woodpecker generally exhibits nest site fidelity (Ingold 1991). In Mississippi, 33% of banded adults (15 out of 45) returned to the vicinity of their previous year’s nest (Ingold 1991). In Florida, one adult male moved 1.04 km between two consecutive breeding seasons (Belson 1998). In Canada, two adult birds first captured during the spring migration were recaptured, presumably at their nest sites, the following year - 240 and 251 km, respectively, from their capture sites (Brewer et al. 2000).

Belson (1998) reports that for three juvenile Red-headed Woodpeckers monitored in Florida, initial dispersal from their natal territories varied from 0.11 to 0.67 km. In Mississippi, out of total of 69 birds banded as nestlings, none returned to the site around their nest tree (Ingold 1991).

Diet and feeding habits

The Red-headed Woodpecker is probably the most omnivorous woodpecker species in North America and relies on both plant (67%) and animal (33%) food (Smith et al. 2000). Its diet includes a wide variety of cultivated and wild fruit (apples, pears, cherries, raspberries, and strawberries), as well as corn and several types of mast (such as acorns and beechnuts) (Short 1982; Smith et al. 2000). The animal portion of its diet consists mainly of insects, such as grasshoppers, crickets, ants, several types of beetles and their larvae, butterflies, caterpillars, wasps, and domesticated bees (Apis mellifera) (Short 1982; Smith et al. 2000). The Red-headed Woodpecker also feeds on bird eggs, young birds, and occasionally adult birds, as well as small rodents, lizards, and dead fish (Smith et al. 2000). In winter, its diet becomes more specialized, focusing on acorns and beechnuts, as well as grains, such as corn (Williams and Batzli 1979). In winter this species will also frequently visit bird feeders to eat sunflower seeds, peanut butter, and suet (animal fat) (Short 1982; Smith et al. 2000).

The Red-headed Woodpecker forages on a variety of substrates and generally prefers live trees, foraging mainly on trunks and branches (Smith et al. 2000). In summer, the Red-headed Woodpecker captures most of its animal prey -- i.e., insects -- by “flycatching” -- flying out from a perch to catch them in the air (Jackson 1976; Venables and Collopy 1989 in Smith et al. 2000).  In winter, this species forages on the ground, as well as in trees and shrubs where it looks for small fruits and insects (Root 1988). Once it has established its winter territory, the Red-headed Woodpecker feeds mainly on acorns that it finds on the ground and in trees, storing them in cavities that it excavates for this sole purpose (Kilham 1983).

Interspecific interactions

The Red-headed Woodpecker is the most pugnacious of all North American woodpeckers and is often seen driving away other species of birds, to protect either its nest or its food caches (Smith et al. 2000). The most heavily documented instances of interspecies aggression involve the European Starling (Sturnus vulgaris) and the Red-bellied Woodpecker (Melanerpes carolinus), two species whose nesting behaviour is similar to that of the Red-headed Woodpecker.

The proportion of Red-headed Woodpecker nest cavities usurped by starlings varies from 7% to 15% (Ingold 1989). Red-headed Woodpeckers are often more aggressive than starlings and can successfully force starlings to abandon a usurped cavity (Ingold 1989, 1994). The short breeding season of starlings and the tendency for later nesting by Red-headed Woodpeckers reduce the competition between the species (Ingold 1989, 1994; Koenig 2003).

The Red-bellied Woodpecker offers the Red-headed Woodpecker serious competition for supplies of mast in fall and winter. Williams and Batzli (1979) have shown that the Red-bellied Woodpecker changes its horizontal distribution and uses different habitats when the Red-headed Woodpecker is present in the same area. On the scale of the nesting site, the Red-bellied Woodpecker also seems to be affected negatively by the Red-headed Woodpecker’s presence. In Mississippi, for instance, six breeding pairs of Red-bellied Woodpeckers lost their nests to the Red-headed Woodpecker (Ingold 1989).

Bock et al. (1971) note that Red-headed Woodpeckers are dominant over Lewis’s Woodpeckers (Melanerpes lewis) at their own cavities. The Red-headed Woodpecker’s absence from Colorado in the winter is probably due to food competition from Lewis’s Woodpecker (Smith et al. 2000).

Other species commonly driven off by the Red-headed Woodpecker are the Downy Woodpecker (Picoides pubescens), the Tufted Titmouse (Baeolophus bicolor), the Blue Jay (Cyanocitta cristata), and the White-Breasted Nuthatch (Sitta carolinensis) (Smith et al. 2000).

Home range and territory

The species’ summer territories range in size from 3.1 to 8.5 ha (Venables and Collopy 1989 in Smith et al. 2000).

Adult as well as juvenile Red-headed Woodpeckers are territorial in winter, aggressively defending well-defined individual territories against both interspecific and intraspeciific competition (Williams and Batzli 1979; Kilham 1983). The adult winter territories are usually small, ranging from 0.2 to 2.0 ha (Kilham 1958; Moskovits 1978; Williams and Batzli 1979).

Behaviour/adaptability

During the breeding season, the Red-headed Woodpecker’s dependence on tree cavities for nesting gives it little flexibility to respond to human disruptions that either reduce the density of dead trees or eliminate them altogether (Smith et al. 2000).

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