Introduction
Total Page：16
File Type：pdf, Size：1020Kb
Copyrighted Material Introduction Identifying raptors is similar to solving a across the United States and Canada are mystery by piecing together clues. By far, the covered. Most of the photographs in this greatest challenge of raptor identification is book were taken during autumn migration naming distant birds. This is because plum- from August 15 to November 30. Birds age details (and sometimes flight style and photographed during spring migration from structure) can be difficult to judge from afar. March to late May or otherwise are noted Even for the most experienced observers, as such. identifying raptors based on plumage alone I am frequently asked which hawk identi- can be flawed. With this in mind, imagine fication problem I believe is the most diffi- how difficult it is to distinguish two species cult. Several come to mind, like telling that are practically identical in plumage, brown Prairie Merlins from female Kestrels like Sharp-shinned and Cooper’s Hawks. at a distance, ageing Golden Eagles to a spe- Even a distinctive plumage trait like the red cific year, telling a Peregrine Falcon from a tail of an adult Red-tailed Hawk can be dif- Prairie Falcon by silhouette, or telling adult ficult to view in the field. With practice,it is female from juvenile Harriers in spring. more accurate to tell similarly plumaged However, some aspects of identification are birds apart by shape and flight-style differ- simply impossible due to overlap or simi- ences than by coloration. I identify most of larities in plumages, like telling the race of the distant raptors I see based on shape and some Red-tailed Hawks, Merlins, or Per- flight style, using plumage traits only if egrine Falcons. Remember, it is enjoyable to clearly visible. Remember, there are excep- simply watch raptors without fussing over tions to every rule, so almost no field mark their age, sex, or race and that learning is 100 percent exclusive to one species. hawk identification is an ongoing process. At any hawk-watching site, a close-up bird will draw “oohs” and “aahs” from ob- HOw tO UsEtHis BOOk servers. But because most hawks seen in the field are distant, Hawks at a Distance is a Hawks at a Distance is designed to show necessary guide. It focuses on distant birds raptors in “real world” settings and help and discusses traits that are truly useful in with identification of birds seen with only a the field, leaving out certain others that can quick glimpse. Therefore, the birds through- only be judged at close range. Be aware that out these pages are meant to appear distant, some field marks may be difficult to see in unlike most guides that present close-up the photos in this book. This is done pur- portraits of birds. Hawks at a Distance posely to show how these field marks truly presents each species in all light conditions. appear in the field. Hawks at a Distance is Each color plate is a composite that includes the first guide that presents birds of un- up to six images and a single caption. They known identity, pointing out instances when are presented this way so that each color telling age, sex, color morph, or species is plate is viewed in its entirety as the descrip- impossible, and showing the effect that tion is read. Throughout the color plates, lighting and molt can have on a bird’s ap- birds are shown in poses (i.e., soaring, glid- pearance. Only migrants that are common ing) in which migrants are normally ob- Copyrighted Material 2 • introduction served. This is intended to stress the shape and easy to understand (see Glossary), but features referred to in the captions of cer- the terms “immature” and “sub-adult” are tain color plates. sometimes unclear. Even some ornitholo- The black-and-white plates portray shape gists disagree on the exact definitions of characters for each species pointed out by these terms. Regardless, the terminology the accompanying captions. These plates throughout this guide is used in a consis- are designed so that the reader’s eyes wan- tent, practical manner. der around the page and take in the entire The term “immature” describes a bird page quickly. The text is short so that it is whose plumage is other than adult. There- easy to remember and so that the book is fore, an immature bird is either a juvenile or uncluttered. Key identification traits are in a sub-adult. Some argue the term “imma- boldface throughout the text, and memoriz- ture” relates to a bird’s sexual maturity re- ing these traits will prove to be useful in the gardless of its plumage. For instance, a field. For example, the traits in boldface for breeding accipiter in juvenile plumage Golden Eagle are “large, dark bird . ex- (which is sometimes the case with females) tremely long, somewhat broad wings . could be regarded as an adult because it is dihedral when soaring, slightly bowed when producing young. However, age terminol- gliding . slow moving and steady.” ogy herein defines a plumage as it pertains One of the keys to identifying raptors is to field identification, not a yearly age or to learn the basic characteristics of each spe- sexual maturity. cies well instead of learning the minutiae for The term “sub-adult” describes a bird each. For example, recognizing the shapes whose plumage is a distinct plumage alto- of each raptor, and understanding how they gether from that of an adult or juvenile. vary under different circumstances, is much Birds in their first adult plumage (that may more valuable than knowing the eye color have none or several juvenile feathers re- of each raptor. Be aware that certain written tained) that are essentially identical or ap- or spoken descriptions (particularly regard- pear identical in the field to successive adult ing wing beat and flight style), and even the plumages are simply “adults.” Most raptors same field observation between various reach adulthood after their first molt cycle people, can be interpreted differently. For starting at about one year old. A few species instance, I once heard the words “stiff,” take about two years, while eagles typically “choppy,” “snappy,” and “aggressive” used take about five years to reach full adult independently by four separate observers to plumage. describe the wing beats of a single bird as it flew by. Color Morph Terminology Throughout this guide, the term “dark” is tErMiNOlOgy used to describe buteos that are mostly or completely dark on the underside. This in- Age Terminology cludes birds otherwise known as “interme- Some age-related terms can be misunder- diate morph” and “dark morph.” Intermedi- stood or misinterpreted. The terms “juve- ate and dark-plumaged birds often appear nile” and “adult” are fairly straightforward identical to each other at a distance, which Copyrighted Material introduction • 3 is why both are simply classified as “dark” glide - To fly forward with wings pulled in birds throughout this guide. About 90 per- (see Flight Positions). cent of dark Swainson’s, Red-tailed, and “Hand” - Consists of all the primaries, the Ferruginous Hawks are truly intermediate outermost part of the wing (see Anatomy). birds, but are mistaken for dark birds regu- Head-on - Eye-level, front profile (see larly. On the other hand, intermediate plum- Flight Positions). ages of Broad-winged and Rough-legged Hover - To remain stationary in flight while Hawks are rare, with dark birds being the flapping (see Flight Positions). norm. I refrain from using the terms immature - All ages other than adult. “morph” and “phase” throughout the text intergrade - A bird showing traits of two since they can be misleading, and instead different races or forms. use the terms “light” and “dark” to describe Juvenile - A bird in its first plumage. a bird’s plumage. kettle - A group of birds soaring together. The term “intergrade” describes a bird leggings - Feathers that cover the legs and with a plumage that falls between two sub- sometimes the feet (see Anatomy). species (like Taiga and Prairie Merlins) or leucism - Presence of some or all white between a subspecies and a recognized form feathers on a normally darker-plumaged of a species (like Krider’s Red-tailed Hawk, bird. Sometimes referred to as albinism. a pale form of the Eastern Red-tailed Melanism - Presence of dark feathers on a Hawk). A hybrid is the offspring of two normally lighter-plumaged bird. separate species; hybrids rarely occur natu- Modified dihedral - Position of wings raised rally, but are commonly bred for falconry. at the shoulder and level at the “wrists” (see Flight Positions). Molt - Replacement of old feathers with glOssAry new feathers; usually occurs from April Adult plumage - A bird in its definitive through September in raptors. plumage. Morph - Color form. Axillaries - Wing pits (see Anatomy). Nape - Back of neck (see Anatomy). Bib - A dark patch of feathers on the Patagium - Area between the “wrists” and breast. body along the leading edge of the wings Buffy - A pale tan coloration. (see Anatomy). Carpal - Underwing area at the “wrist” Primaries - Ten outer remiges or “hand” of where all the primaries meet (see the wing; the notched outer primaries Anatomy). make up the “fingers” of a hawk (see Cere - Flesh between the bill and forehead. Anatomy). Crown - Top of the head. rectrices - Tail feathers. dihedral - Wings held above the plane of remiges - Secondaries and primaries. the body in a “V” position (see Flight rufous - An orange-rust color. Positions). “rump” - Feathers covering the bases of dilute plumage - An overall light tan plum- the uppertail coverts (see Anatomy). age on a normally darker bird. scapulars - Feathers along the sides of the Flight feathers - Primaries, secondaries, and back (see Anatomy).