Excerpted from Chapter 1: What Is a Woodpecker? Woodpeckers are among the most ancient of all birds. A 25-million-sear-old fossil leg bone from Germany, a feather trapped in Caribbean amber that dates back an least 24 million years, and cavities in 40- to 50-million-year-old petrified wood from Arizona and Wyoming offer tantalizing clues as to when woodpeckers first diverged from their less specialized ancestors. The question of where this happened remains shrouded in mystery. The Americas, Asia and Africa have each been proposed by different experts as the home of the earliest woodpeckers. Today, members of the Picidae or woodpecker family (often referred to as picids) are found on every continent except Australia and Antarctica and inhabit many of the world's major islands, the most notable omissions being New Zealand, New Guinea, the Oceania island chain in the South Pacific, Hawaii, Madagascar, Greenland and Iceland. This large family is divided into three sub-families: the Jynginae or wrynecks. represented by two species; the Picumninae or piculets, with 31 species; and the Picinae, also known as the true woodpeckers, with 183 species. No wrynecks or piculets reside in North America. All of the true woodpeckers are hole-nesters with the ability to excavate their own cavities, generally in trees or tree substitutes such as columnar cacti or telephone poles. As a result, to a greater or lesser extent the Picinae subfamily has a number of distinctive morphological (structural) features: a long, stiff tail for bracing against tree trunks; short legs and long toes to assist in climbing vertical surfaces; a head built to withstand repeated hammering against hard surfaces; a long, straight bill designed for chopping into wood, removing bark or probing into crevices; a long, extensible tongue with a barbed end, able to reach deep into narrow openings and extract hidden prey; and nostrils covered with feathers to keep them free of wood debris. These attributes (described in more detail in Chapter 2) are displayed most completely by the most highly specialized tree excavators The first part of a species' scientific name indicates the genus (plural: genera) to which it belongs. The second part completes its unique species identification. Worldwide there are 24 genera within the Picinae subfamily. The true woodpeckers are represented by seven genera in North America -- Picoides , Melanerpes , Sphyrapicus , Colaptes , Piculus , Dryocopus and Campephilus -- which together include 28 species. Because members of the same genus are more closely related to each other than to other woodpeckers, they typically share certain physical characteristics, including body size and plumage patterns, as well as behavioral traits such as feeding habits. Woodpeckers that belong to the same genus often wear similar "sexual badges", the red (or in a few cases. yellow) head markings that differentiate adult males and females of most species. Only three North American woodpecker species -- the red-headed woodpecker, Lewis's woodpecker and the red-breasted sapsucker -- are sexually monochromatic, meaning that males and females cannot be distinguished by their plumage colors and patterns. All other North American woodpeckers are dichromatic, meaning that adult males and females have different plumage. Males of these latter species invariably display more conspicuous sexual badges than their female counterparts. The females may have no equivalent markings or their badges may be a smaller or less prominent version of the male's. Sexual size differences are not pronounced in most woodpecker species. The genus Picoides is the largest in North America, with nine species: the American three-toed, Arizona, black-backed, downy, hairy, ladder-backed, Nuttall's, red-cockaded and white-headed woodpeckers. Sometimes collectively referred to as pied woodpeckers because of their mixed black-and-white plumage (brown-and-white in the case of the Arizona woodpecker), these are small to medium-sized woodpeckers. Their sexual badges are red -- except for those of the American three-toed and black-backed woodpeckers, whose males sport yellow caps -- and are worn on the forehead, crown or nape. In this genus the males tend to be slightly heavier than females and have proportionally longer bills and shorter tails, though these differences are not generally obvious in the field. The Picoides woodpeckers have straight, chisel-tipped bills and are largely insectivorous. Excerpted from Woodpeckers of North America by Frances Backhouse All rights reserved by the original copyright owners. Excerpts are provided for display purposes only and may not be reproduced, reprinted or distributed without the written permission of the publisher.
