Saturday, July 31, 2021

The Red-cockaded Woodpecker: A Life History

It occurs to me from time to time that I am privileged to live in an area where I can regularly see a federally Endangered bird species—the Red-cockaded Woodpecker—if I choose.  These woodpeckers have small colonies at several locations in and around Noxubee National Wildlife Refuge, and they are relatively easy to detect—all a birder has to do is listen carefully for the raspy, nasal calls in the refuge’s pine woods.  If one of these medium-sized, black-and-white woodpeckers comes into view, it can be distinguished from the far more common Downy and Hairy Woodpeckers by its white cheek patches and completely barred back.  (Downy and Hairy Woodpeckers, in contrast, have striped faces and white backs.)  Males of the species have red feathers—the “cockades”—on the sides of the crown, but, because these are tiny and seldom displayed, they are not a particularly important field mark.

Note the barred back and the white cheeks

This endangered woodpecker is restricted to open pine forests with sparse understories of palmettos, grasses, shrubs, and other plants.  The open nature of the habitat is a consequence of natural fires, which restrict understory growth and possibly leave younger trees more susceptible to Phellinus pini, or red heart, a fungal disease that damages the heartwood of infected pines.  The softened, diseased wood can then be more easily excavated by Red-cockaded Woodpeckers, which will dig cavities 5-50 feet high in living trees infected with red heart.  Many of these infected trees are well over 40 years in age.  The birds peck into the sapwood above and below the cavities that they create, which results in a flow of sap that deters predators (such as rat snakes) and other animals from accessing the roost or nest holes.

Open pine habitat in early spring

Like most woodpeckers, Red-cockaded woodpeckers make various vocalizations at the nest and during courtship and other encounters.  Drumming on trees—usually pines—is another common means of communication, as are wing-fluttering, open-winged displays, and crest-raising.  The spread-winged display is used to reinforce the pair bond between a male and female.  Eggs are laid from late April to early June in a pre-existing cavity, rather than one that is excavated specifically for a nest.  The eggs are white in color, and become stained with pine resin over the course of the incubation period.  The female of the pair lays one egg per day, with one to six eggs comprising a clutch.  Incubation, which lasts about ten days, is performed by both parents, with the male incubating overnight.  Both parents feed and tend the altricial, pink-skinned, featherless nestlings.  Although the young birds fledge after about 26-29 days, they are at least partially dependent on their parents for up to six months afterward.  The Red-cockaded Woodpecker’s propensity for living in loose colonies or family groups benefits it during the nesting period, as unmated “helper” birds may aid breeding pairs in feeding nestlings and fledglings.  Usually, a pair has only one brood per year.

A foraging Red-cockaded Woodpecker

Interestingly, male and female Red-cockaded Woodpeckers are somewhat segregated according to the types of feeding sites that they use, with males foraging on branches and high on the trunks of pines, and females preferring to forage at lower elevations and only on the trunks.  For this reason, I suspect that most of the Red-cockaded Woodpeckers that I have seen near the refuge’s Visitor Center have been females.  Both sexes eat mainly insects and other arthropods, including cerambycid beetles, larvae and grubs of various species, ants, and millipedes.  On occasion, they will also consume small fruits and seeds. 

Although the Red-cockaded Woodpecker is a fairly widespread species, it is patchily distributed due to its highly specialized niche.  It is considered an endangered species across its range, which extends from the southeastern Atlantic Coast to Oklahoma and Texas.  Habitat loss remains the most serious threat to these woodpeckers, so conservation efforts generally focus on preserving tracts of large pines and subjecting them to controlled burning to clear the understory layers.  Any birder or naturalist who is fortunate enough to live near one of the managed populations would do well to keep a sharp eye—and ear—out for these fascinating little woodpeckers during this summer and fall.


Source:

Ligon, J. D.  1970.  Behavior and breeding biology of the Red-cockaded Woodpecker.  Auk        87(2):255-278.

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