|Eurasian three-toed woodpecker (P. tridactylus), adult male and the three-toed foot which lacks the first digit|
The name of the genus was introduced by the French naturalist Bernard Germain de Lacépède in 1799. The word Picoides combined the Latin Picus for a woodpecker and the Greek -oidēs meaning resembling.
The genus Picoides formerly contained around 12 species. In 2015 a molecular phylogenetic analysis of nuclear and mitochondrial DNA sequences from pied woodpeckers (the tribe Dendropicini) found that three existing genera (Picoides, Veniliornis and Dendropicos) were polyphyletic. After the creation of six new monophyletic genera and the subsequent rearrangement in which most of the former members of Picoides were moved to Leuconotopicus and Dryobates, only three of the original species remained. Some taxonomic authorities, including the American Ornithological Society, continue to place some of the species now found in Dryobates and Leuconotopicus here.
The males of all three species have yellow on the crown, though this feature is also present in some other pied woodpeckers, namely brown-fronted and yellow-crowned. The remaining color pattern of the plumage, structural features, and life habits are very similar to related woodpeckers of the Dryobates and Leuconotopicus genera. The foot of all three species show an extreme adaptation to arboreal living by lacking the first digit, or hallux. It has been pointed out however that various species of pied woodpecker are similar in having a short first digit. Two species of woodpecker in genus Sasia (not closely related) also lack the first digit.
As opposed to genus Dryobates, the three species of Picoides obtain most (some 85%) of their insect prey by pecking live or dead wood. The hairy woodpecker (Dryobates villosus) for instance, obtains only 45% of its food by pecking wood, 30% from the surface of trunks and 25% at other places.
The genus contains the following three species:
- Lacépède, Bernard Germain de (1799). "Tableau des sous-classes, divisions, sous-division, ordres et genres des oiseux". Discours d'ouverture et de clôture du cours d'histoire naturelle (in French). Paris: Plassan. p. 7. Page numbering starts at one for each of the three sections.
- Jobling, James A. (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. p. 306. ISBN 978-1-4081-2501-4.
- Fuchs, J.; Pons, J.M. (2015). "A new classification of the pied woodpeckers assemblage (Dendropicini, Picidae) based on a comprehensive multi-locus phylogeny". Molecular Phylogenetics and Evolution. 88: 28–37. doi:10.1016/j.ympev.2015.03.016. PMID 25818851.
- Gill, Frank; Donsker, David (eds.). "Woodpeckers". World Bird List Version 6.2. International Ornithologists' Union. Retrieved 5 May 2016.
- Delacour, J. (January 1951). "The significance of the number of toes in some woodpeckers and kingfishers" (PDF). The Auk (American Ornithological Society). 68 (1): 49–51. doi:10.2307/4080797. Retrieved 20 September 2018.
- "Picoides funebris". International Union for Conservation of Nature and Natural Resources. Retrieved 2014-12-30.