Audubon Online Guide to North American Birds now Available
The Audubon Online guide covers all species of birds that breed in or regularly visit North America north of Mexico, as well as many of the rarer visitors. The species are generally grouped and ordered according to the checklist of the American Ornithologists’ Union (AOU) which begins with what are thought to be the most ancient families and continues in phylogenetic sequence to the more recently evolved. To aid beginning birders with some of the more common identification problems, birds with similar structural features, especially the shape of the body and bill, are grouped together in this Resources section of the guide so that similar looking birds are shown together to better illustrate their differences. For example, the unrelated Great Blue Heron and Sandhill Crane— both tall, grayish birds with a long neck and a long, pointed bill–are shown juxtaposed.
Group introduction essays
The BIRD FAMILIES section of this "RESOURCES" content begins with an introductory essay that gives general information on the group, including which families the species belong to, physical characteristics common to the group as a whole, and general information on habitat, foraging and breeding behaviors, and conservation.
Names and measurements
The common and scientific names of the species follow those given by the AOU. The length (L), from bill to tail tip, and the wingspan (W), from wingtip to wingtip, are given in both English and metric measurements.
Every bird has a scientific name consisting of two Greek or Latin words. The first word is the genus and the second is the species. The genus, which is always capitalized, may include a number of species. Since common names vary not only from country to country but even from region to region within North America, the scientific names identify birds everywhere and provide ornithologists with an international language.
Captions and labels
For most of the species covered, the guide includes photographs of the plumages you are most likely to observe in North America. These can include breeding and non-breeding adults, male and female (if distinguishable in the field), various nonadult plumages (labeled as juvenile, immature, subadult, 1st fall, etc.) and some of the more distinctive subspecies.
The information provided for each species is intended to aid in identification and in understanding the species’ natural history and distribution. The text may discuss winter and summer habitats, unique behaviors, diet and foraging techniques, courtship and nesting strategies, physical characteristics, and comparisons with similar-looking species. The descriptions and transliterations of the songs and calls give a rough idea of the species’ primary vocalizations. Many of the descriptions mention the pitch of a song or call, which can range from almost inaudibly high (as in the end of the Blackburnian Warbler’s song) to almost inaudibly low (as in the owl-like hooting of a displaying Dusky Grouse). Musical terminology is occasionally employed: "crescendo" and "decrescendo" for sounds that grow increasingly louder or softer, "modulated" for burry, buzzy, or scratchy sounds (as opposed to "pure-toned" or "sweet" or "clear"), and "syncopated" for songs that seem to have irregular rhythms or unexpected stresses.
The maps indicate typical North American ranges of the species, including winter and summer ranges and migration routes. Rare or extralimital occurrences are shown in some cases.
The American Ornithologists’ Union (AOU) is the international body that maintains the official checklist of wild birds recorded in the Americas, The American Ornithologists’ Union Check-list of North American Birds. This field guide generally follows the AOU’s nomenclature for the birds of North America—that is, the English and scientific names the organization designates as correct for those species. The AOU arranges the checklist in phylogenetic order, a linear sequence that attempts to represent evolutionary relationships among birds, with closely related species grouped more closely together; the first species in the checklist are thought to be the most ancient, the last the more recently evolved. Ornithologists revise the accepted sequence of the list from time to time. Because of recent discoveries based on DNA analysis and other biochemical evidence, the longstanding placement of loons at the beginning of the list (through most of the 20th century) has changed. More changes will likely occur in the future.
The Resources section of this Guide does not rely strictly on the AOU’s sequencing of species; the birds are sometimes grouped according to basic similarities that pose identification problems for beginning birders.
Find out more at: http://birds.audubon.org/birdid