Picidae

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The avian family Picidae includes the woodpeckers, piculets and wrynecks. Members of this family are found worldwide, except for Australia, Madagascar, and the extreme polar regions. Most species live in forests or woodland habitats, although a few species are known to live in desert areas.

Family Picidae is just one of the eight families in the order Piciformes. Members of the order Piciformes, such as the jacamars, puffbirds, barbets, toucans and honeyguides, have traditionally been thought to be very closely related to the woodpeckers, piculets and wrynecks. Recent molecular research has strengthened this view.

There are about 218 species and 28 genera in this family. Many species are threatened or endangered due to loss of habitat or habitat fragmentation. Two species of woodpeckers, the Ivory-billed Woodpecker and the Imperial Woodpecker, have been considered extinct for about 30 years (there has been some controversy recently whether these species still exist).

Species of the family Picidae range in size from 8 cm to 58 cm in length. Most species possess predominantly white, black and brown feathers, although many piculets show a certain amount of gray and olive green. In woodpeckers, many species exhibit patches of red and yellow on their heads and bellies. Although the genders of a species tend to look alike, male woodpeckers will have brighter reds and yellows than the females.

Members of the family Picidae have strong bills for drilling and drumming on trees and long sticky tongues for extracting food. Woodpecker bills are typically longer, sharper and stronger than the bills of piculets and wrynecks, however their morphology is very similar. Due to their smaller bill size, many piculets and wrynecks will forage in decaying wood more often than woodpeckers. The long sticky tongues, which possess bristles, aid these birds in grabbing and extracting insects deep within a hole of a tree.

Woodpeckers, piculets and wrynecks all possess zygodactyl feet. Zygodacytl feet consist of four toes, two facing frontward and two facing back. This type of foot arrangement is good for grasping the limbs and trunks of trees. Members of this family can walk vertically up a tree trunk, which is beneficial for activities such as foraging for food or nest excavation.

The diet of these birds consists mainly of insects, such as ants and beetles, nuts, seeds, berries, some fruit and sap. Species may feed generally on all of these, or may specialize on one or two.

All members of the family Picidae nest in cavities. Woodpeckers and piculets will excavate their own nests, but wrynecks will not. The excavated nest is usually only lined from the wood chips produced as the hole was made. Many species of woodpeckers excavate one hole per breeding season, sometimes after multiple attempts. It takes around a month to finish the job. Abandoned holes are used by many other birds and animals, such as flying squirrels.

Members of Picidae are typically monogamous. A pair will work together to help build the nest, incubate the eggs and raise their altricial young. However, in most species the male does most of the nest excavation and takes the night shift while incubating the eggs. A nest will usually consist of 2-5 round white eggs. Since these birds are cavity nesters their eggs do not need to be camouflaged and the white color helps the parents to see them in dim light. The eggs are incubated for about 11-14 days before the chicks are born. It takes about 18-30 days before the young are ready to leave the nest.

Picidae species can either be sedentary or migratory. Many species are known to stay in the same area year around while others, such as the Eurasian Wryneck and the Yellow-bellied Sapsucker, travel great distances from their breeding grounds to their wintering ground.

References

Johansson, U.S., Ericson, G.P. (2003) Molecular support for a sister group relationship between Pici and Galbulae (Piciformes sensu Wetmore 1960). Journal of Avian Biology. 34:185-197

Koenig, W.D., Haydock, J. (1999) Oaks, acorns, and the geographical ecology of acorn woodpeckers. Journal of Biogeography. 26:159-165

Lemaitre, J., Villard, M.A. (2005). Foraging patterns of pileated woodpeckers in a managed Acadian forest: a resource selection function. Canadian Journal of Forest Research. 35:2387-2393

Michalek, K.G., Winkler, H. (2001) Parental care and parentage in monogamous great spotted woodpeckers (Picoides major) and middles spotted woodpeckers (Picoides medius). Behavior. 138:1259-1285

Stark, R.D., Dodenhoff, D.J., Johnson, E.V. (1998) A quantitative analysis of woodpecker drumming. The Condor. 100: 350-356

Villard, P., Cuisin, J., Karasov, W.H. (2004). How do woodpeckers extract grubs with their tongues? A study of the Guadeloupe woodpecker (Milanerpes herminieri) in the French Indies. Auk. 121:509-514

Webb, D.M., Moore, W.S. (2005) A phylogenetic analysis of woodpeckers and their allies using 12S, Cyt b, and COI nucleotide sequences (class Aves; order Piciformes). Molecular Phylogenetics and Evolution. 36:233-248

Wiebe, K.L., Swift, T.L. (2001) Clutch size relative to tree cavity size in northern flickers. Journal of Avian Biology. 32:167

Wiktander, U., Olsson, O., Nilsson, S.F. (2000) Parental care and social mating system in the lesser spotted woodpecker Dendrocopos minor. Journal of Avian Biology. 31:447

Yom-Tov, Y., Ar, A. (1993) Incubation and fledging durations of woodpeckers. The Condor. 95:282-287