The list below has been edited by WCHW to include the more Raptor specific finer points and words of Raptor ID and habitat.
Aberrant -- Atypical; an aberrant bird differs strikingly in some aspect from most individuals of its species.
Alternate plumage --In most bird species, the plumage worn during the breeding season; often more vividly colored and patterned than the nonbreeding (or basic) plumage, particularly in males.
Altitudinal migration --Seasonal movement of birds along elevational gradients, normally downslope in the cooler months and upslope in the warmer.
Arm --Informal term for the inner portion of the wing between the body and the carpal joint; often used by hawk-watchers.
Aspect ratio --In birds, the ratio of wing length to wing breadth.
Auriculars --Feathers covering the center of the "cheeks" just behind the eyes, visible as a distinct patch in some species (such as Golden-winged Warbler); also called "ear coverts."
Aviculture --The breeding and raising of birds in captivity; when such species are cross-bred, new "strains," or types, are sometimes created that do not closely resemble their wild ancestors (as in Eurasian Collared-Dove and Rock Pigeon).
Axillaries --Group of stiff covert feathers located on the underwing next to the body (in the "armpit" region).
Basic plumage --In most bird species, the plumage worn during the nonbreeding season; often less strikingly patterned or colored than breeding (or alternate) plumage.
Belly --Section of a bird's underparts below the breast and before the vent.
Bib --Informal term for a distinctly pigmented area of the throat, usually a dark patch (as seen on many chickadees).
Bog --Area of soft, spongy, naturally waterlogged ground, typically having an acidic substrate of sphagnum moss and peat, in which characteristic shrubs and herbs and sometimes trees grow.
Boreal forest --Also called "taiga"; continuous belt of subarctic coniferous forest just below the tundra, in North America extending mostly from Alaska to eastern Canada.
Brackish --Characterized by a mixture of salt and fresh water, as found in tidal areas such as bays, lagoons, and marshes.
Breast --Section of a bird's underparts below the throat and before the belly.
Breastband --Area of continuous, contrastingly pigmented plumage that extends across the breast (as in Semipalmated Plover).
Brow line --Line extending from the eye to the base of the maxilla (as in Razorbill).
Call --A usually brief vocalization birds use for contact, alarm, or warning or to solicit feeding, copulation, or gathering (compare "song").
Cap --Informal term for the top a bird's head when it is contrastingly pigmented (as in chickadees); more extensive than the "crown."
Carpal joint --The forward-projecting "wrist" of the wing, characterized by an obvious bend; a carpal bar is an area of contrastingly pigmented plumage that extends, usually diagonally, from this joint along the upperwing coverts toward the body (as in storm-petrels); a carpal patch is a distinct area of plumage near the joint, often on the underwing (as in Rough-legged Hawk).
Cere --Raised, fleshy area at the base of the maxilla, naked in diurnal raptors (Falconiformes), feathered in parrots, and covered with an operculum (flap) in pigeons.
Chaparral --Habitat dominated by a dense growth of mostly small-leaved evergreen shrubs that is found mainly in the West and Southwest and is characterized by hot, dry summers and cool, moist winters.
Cheek --Informal term for the area of a bird's head that includes the auriculars and surrounding feather tracts.
Chin --Informal term for the uppermost part of a bird's throat, adjacent to the mandible.
Clear-cut --Tract of woodland in which all trees have been removed.
Closed forest --Relatively dense forest that has a well-developed canopy (compare "open woodland").
Coastal plain --Area of flatland adjacent to a seacoast; the Atlantic Coastal Plain stretches some 2,200 miles (3,540km) from Cape Cod, Massachusetts, southward through the southeastern United States and Mexico to the Yucatan Peninsula.
Coast Ranges --Mountain ranges that stretch along the western coast of North America from southeastern Alaska to Mexico.
Collar --Informal term for a distinctly pigmented area of plumage that encircles the neck and/or breast.
Colony --In birds, usually a group of the same species nesting together in close proximity; some birds, especially terns, herons, and egrets, nest in colonies comprised of several species, and some birds nest in widely scattered colonies.
Coniferous forest --Woodland composed of mostly evergreen, cone-bearing trees or shrubs with needlelike or scalelike leaves, including pines, spruces, and junipers.
Contour feathers --Feathers that form the outer layer of a bird's plumage, including remiges and rectrices.
Corvid --A bird of the family Corvidae.
Cosmopolitan --Having a nearly worldwide distribution.
Coverts --Contour feathers that lie over (or partly cover) other feathers and serve to protect them and to streamline the bird. Uppertail and undertail coverts cover the base of the tail on the upperside and underside of the body, respectively. Wing coverts are arranged in distinct tiers in many birds, especially larger species: greater coverts are the largest and closest to the remiges, median coverts form the next tier, lesser coverts the next, and marginal coverts are found along the very edge of the wing. Wing covert feathers may be further distinguished according to whether they cover primaries or secondaries and/or the upperside (upperwing coverts) or underside (underwing coverts): greater underprimary coverts are the greater coverts that cover the bases of the primaries (but not the secondaries).
Covey --Group of game birds, especially smaller species such as quail.
Crest --Group of crown feathers that show a peak or elongation; adults of some species are always obviously crested, while others may raise a small crest only when alarmed.
Crop --In some birds, a saclike area between the throat and esophagus used to store food before regurgitation or digestion.
Crown --Area of feathers on top of the head above the eyes, bordered by the forehead and nape (less extensive than a "cap"); a crown patch is an area of distinctly pigmented feathers in the center of the crown; a crown stripe extends along the length of the crown, either down the center (median crown stripe) or along the sides of the center (lateral crown stripes).
Deciduous woodland --Woodland comprising mostly or solely trees that shed their foliage at the end of the growing season, usually autumn or winter.
Desert wash --A usually dry desert streambed that flows only after periods of heavy rain.
Dimorphic --In a population or species, occurring in two forms that differ in size, shape, or coloration, frequently involving differences between male and female (sexual dimorphism) or color morphs.
Dispersal --Movement away from breeding areas by adults or young; usually distinguished from "migration" in being less regular or predictable.
Display --Innate, stylized activity or signal through which birds communicate.
Diurnal --Active by day.
Dorsal --Pertaining to the upperside of the body; in birds, refers especially to the tail, back, and wings.
Dredge-spoil island --Shoal or small island created by the deposition of sediment from dredging operations, usually in connection with the maintenance of ship channels.
Endemic --Native to or confined to a certain region and found nowhere else.
Estuary --Passage of the lower course of a river where its current meets the tides and the water is brackish.
Eye line --Line formed by dark plumage that extends through or behind the eye; also called an "eye stripe" (a term some sources use to indicate a thicker line).
Eye patch --Area of dark plumage around the eye.
Eye ring --Area of contrasting plumage encircling the eye (compare "orbital ring").
Facial disc --Group of feathers that surround the eyes of certain birds, particularly owls, in which the disc is often clearly defined.
Facultative movements --In birds, movements made in response to pressures or stresses in the immediate environment, such as food crop failures, drought, cold, or snow cover (compare "migration").
First-year bird --Bird in its first 12 months of life; a first-winter bird is in its first winter, a first-fall bird in its first fall.
Flanks --Rear portion of the sides, from about the midpoint of the folded wing to the tail coverts.
Fledge --To grow a first set of contour feathers (as opposed to a coat of downy feathers), or juvenal plumage.
Fledgling --Bird that has fledged (acquired juvenal plumage) and left the nest; most birds begin to become independent of their parents at this time (compare "nestling"), although precocial birds leave the nest as downy chicks, long before acquiring their first set of contour feathers.
Flight call --Call used chiefly by flying birds, thought to function as a contact call among members of the same species, especially during nocturnal migration.
Flycatch --To capture flying insects while in flight.
Forecrown --Foremost part of the crown; a smaller area than the forehead.
Forehead --Front of the head, above the maxilla.
Frontal shield --Featherless, fleshy plate on the forehead, often brightly colored (as in Purple Gallinule).
Frontlet --Small area of distinctly delineated plumage near the foremost portion of the forehead.
Gape --Angle of the bill where the maxilla meets the mandible.
Glean --To pick small food items singly, usually with delicate movements; warblers glean insects from leaves or needle clusters.
Grassland --Area with extensive grass or grasslike vegetation, such as a prairie or meadow.
Hand --Informal term for the outer portion of the wing past the carpal joint; typically used by hawk-watchers.
High Arctic --Area above the Low Arctic, where tundra vegetation is replaced by cushion plants, rock-brake ferns (Cryptogramma), prostrate shrubs, and rosette-forming herbs.
Hindcrown --Rear part of the crown, just forward of (above) the nape.
Hover-glean --To forage while fluttering in the air; kinglets often hover-glean insect larvae from the outer needle clusters of spruce trees.
Humerals --Feathers of the inner portion of the wing that lie along the humerus (wing bone nearest the body).
Hybrid --Offspring resulting from the breeding of different species (compare "intergrade"); certain bird species, including gulls, orioles, hummingbirds, and sapsuckers, regularly or occasionally hybridize.
Immature --Bird that is not yet an adult in plumage. (In this book, "immature" does not refer to a bird's ability to breed, as many species can breed in plumages other than definitive adult plumage.)
Impoundment --Body of water, such as a reservoir or marsh, contained by manmade boundaries, especially earthen dams.
Intergrade --Offspring resulting from the breeding of different subspecies (compare "hybrid").
Interior West --Area of the western United States south of Canada that lies east of the Sierra Nevada and west of the Great Plains.
Intertidal zone --Area of a shoreline between the low- and high-tide points.
Irruption --Large-scale movement of a species outside its typical range, usually in autumn or winter; such movements do not occur in regular, predictable patterns, unlike migration.
Juvenal plumage --A bird's first covering of contour feathers; it is often brown or streaked.
Juvenile --Bird in juvenal plumage.
Kite --In bird flight, to hang in one position while facing into the wind with minimal or no flapping.
Kleptoparasite --Bird that forages by stealing food from other birds (such as Parasitic Jaeger).
Lagoon --Sheltered, shallow body of water separated from deeper, more open water.
Leucism --Condition of plumage resulting from reduced pigment in feathers; leucistic birds vary from having a few stray whitish feathers to being nearly all white with just a trace of normal pigmentation (the latter resembling albino birds but with normally pigmented eyes).
Lift --Upward force exerted on a wing due to air flow across its surface.
Lore --Area between the eye and the base of the bill; some species have distinctively colored lores (such as White-throated Sparrow).
Lowland --Area of level land that is lower in elevation than surrounding land.
Malar --Small group of feathers, sometimes distinctively colored, that extends from the base of the bill downward and slightly backward along the throat (see "submalar stripe").
Mandible --Lower part of a bird's bill; sometimes called "lower mandible" (compare "maxilla").
Mangrove forest --Or mangrove swamp; low, dense woodland of tropical evergreen trees or shrubs that grow in coastal tropical and subtropical areas (of southern Florida and Texas in the scope of this guide); these plants, which grow in salt water, have stiltlike roots and stems and are important roosting and nesting sites for birds.
Mantle --In this guide, feathers of the upper back, not including the scapulars; in other publications, the term may also be used to include the scapulars and all visible upperwing coverts of the folded wing.
Mask --Informal term for an area of dark plumage extending from the base of the bill through and beyond the eyes (as in Loggerhead Shrike).
Mesquite --Small, spiny trees or shrubs (genus Prosopis) that grow in hot, dry climates.
Migration --Regular movement of birds between nesting and wintering areas, generally stimulated by changes in the duration of daylight rather than a weather event or food shortage (compare "facultative movements").
Mob --In birds, to gather around a perched predator (or pursue a flying predator) while calling vigorously ("scolding") and sometimes making swooping flights to strike; mixed flocks of small birds will often mob an owl in daylight.
Molt --The process of shedding old feathers and replacing them with new feathers, whether all or part of the plumage; most species have regular, predictable molts.
Monogamy --The condition of having only one mate during a breeding season or during the breeding life of a pair.
Morph --In birds, a variation, usually in plumage, found within a population or an entire species; often called "color morph" (formerly "plumage phase," although the condition is permanent).
Mudflat --Area of mud along rivers, lakes, or other water bodies usually exposed by receding tides or by drought; often important habitat for foraging shorebirds and waterbirds.
Muskeg --Habitat characterized by an acidic, very moist soil type common in Arctic and boreal areas that is made up of dead plants in various states of decomposition and often includes sphagnum moss and sedge peat; often found along the uneven interface of taiga and tundra, where there are few and stunted trees.
Nail --Distinct horny plate at the end of the maxilla or mandible, most pronounced and obvious in larger tubenoses (in the order Procellariiformes).
Nape --The back of the head, including the hindneck, just below the hindcrown.
Nearshore waters --Ocean waters between the low-tide point and a depth of about a hundred fathoms (200m).
Neotropical --Of the New World tropics, which extend from southern Mexico through Central America into South America; a "Neotropical migrant" passes the nonbreeding season in this area.
Nest box --Box with an entrance hole set out specifically for cavity-nesting birds, such as wrens, woodpeckers, owls, and parids.
Nestling --Young bird that has not yet left the nest.
Oak scrub --Open, fairly dry habitat consisting of shrubby, thicket-forming oaks.
Offshore waters --Open ocean waters, rather than nearshore waters; also called "pelagic waters" (see also "pelagic").
Old-growth forest --Mature woodland ecosystem characterized by the presence of old woody plants, especially old trees, and the wildlife and smaller plants associated with them.
Open woodland --Woodland community characterized by widely spaced trees or an open, broken canopy (such as a pine savanna).
Orbital ring --Ring of often brightly colored bare skin encircling the eye (as in Black-billed Cuckoo).
Ornithologist --Scientist who studies birds.
Oscines --Collective term for a suborder (Passeri) of the songbirds (passerines); see also "suboscines."
Pacific Slope --The part of western North America that drains to the Pacific Ocean.
Pack ice --Floating sea ice that has been driven together into a mass.
Parid --A bird of the family Paridae.
Passerine --Any bird in the order Passeriformes; passerines are often called "perching birds."
Peep --Small shorebird of the genus Calidris, usually applied only to Least, Semipalmated, Western, Baird's, and White-rumped Sandpipers and not to larger Calidris.
Pelagic --Relating to deepwater ocean regions (see also "offshore waters").
Permanent resident --Nonmigratory species found year-round in a given area; sometimes refers to a species that makes short-distance (and/or facultative) movements, replacing local birds with birds of the same species from other areas in the nonbreeding months.
Phenotype --Observable physical properties of an organism.
Phylogenetic --Based on evolutionary history; used in the context of evolutionary relationships among taxa.
Pine barren --Area of infertile land that is dominated by pines and has limited understory vegetation (found in eastern North America).
Pinyon-juniper woodland --Habitat found on the lower slopes of mountains, consisting of short evergreen trees--mostly one or more species of pinyon pine (Pinus) and juniper (Juniperus)--mixed with desert and upland shrubs or open grasslands.
Pishing --Giving vocal imitations of parid calls (that sound a bit like steam escaping in quick bursts) to attract woodland birds.
Plunge-dive --To dive on aquatic prey from the air.
Pocosin --Freshwater bay swamp (bays are broadleaf evergreen trees of various families) in the Atlantic Coastal Plain.
Polyandry --The condition of a female having more than one mate in a breeding cycle.
Polygyny --The condition of a male having more than one mate in a breeding cycle.
Polymorphic --Having one or more distinct types within a population, usually referring to plumage types (or "morphs").
Prairie --Extensive area of flat or rolling, mostly treeless grassland, especially the large tract or plain of central North America known as the Great Plains.
Primaries --The outermost and longest remiges, usually numbering between 9 and 12, that with their coverts form the outer portion of the wing.
Primary projection --The length of the primaries that projects past the tertials when the wing is folded (of particular use in the identification of certain passerines).
Primary shaft --The stiff central axis of the primary feather, sometimes distinctly visible in flying birds if the feather color is contrastingly dark (as in jaegers).
Range --Geographic area typically occupied by a species.
Raptor --Bird of prey, usually referring to a falcon, hawk, or owl.
Rectrices -- (singular: rectrix)Tail feathers, not including the tail coverts.
Remiges --Flight feathers, including the primaries and secondaries but not their coverts.
Resident --Usually nonmigratory and present throughout the year.
Rictal bristles --Hairlike feathers that project from the gape area and are thought to aid in the capture of aerial insects by trapping them or serving a tactile function.
Riparian --Along the banks of a flowing natural watercourse such as a river; a riparian forest is found along a stream or river and does not extend far from the banks.
Riverbottom swamp --Bottomland hardwood forest with a river that moves very slowly through it (mostly southern United States); "bayou" is sometimes a local synonym.
Rump --Lower back above the uppertail coverts and below the mantle.
Sage scrub --Arid, mostly treeless habitat of the American West that is dominated by sage (Salvia, Artemisia, and other genera) and other low-growing plants; coastal sage scrub, found mostly in southern California, is a particular habitat that features species of sage and various shrubs, cacti, and grasses adapted to the semiarid climate of that region.
Saltpan --Shallow basin in a desert region containing salt and gypsum deposited by an evaporated salt lake; also a flat area of dry or drying salt water that opens or once opened onto tidal water.
Savanna --Ecosystem characterized by widely spaced overstory trees (often pines) and open expanses in the understory, which is usually grassy or herbaceous in patches; in this book, mostly refers to habitats of the southeastern United States involving loblolly and longleaf pines.
Scapulars --Group of feathers that lies along the margins of the mantle or back and also overlaps the folded wing.
Scree --Loose rock debris covering a slope.
Scrub --Dry habitat (also called "scrubland") characterized by short or stunted vegetation, sometimes but not always with heavy undergrowth.
Scrub oak --Informal term applied to several species of thicket-forming shrubby oaks.
Secondaries --The remiges of the inner part of the wing.
Second-growth woodland --Trees that grow to cover an area after the original stand has been removed.
Shortgrass prairie --Arid habitat of the western Great Plains, just east of the Rocky Mountains, characterized by sparse, low vegetation, little rainfall, and periods of severe drought.
Shrub-steppe --Habitat, found from eastern Washington and Oregon to western Wyoming and Colorado, characterized by grasses and shrubs, including big sagebrush, rabbitbrush, greasewood, bitterbrush, buckwheat, and hopsage.
Sinkhole --Natural depression that connects with a subterranean passage, generally occurring in limestone regions.
Slough --(Pronounced "slew" or "slou.") Marshy area, lake, or pond that lacks inflowing water; can be locally synonymous with "bayou" and "backwater."
Song --Vocalization used mostly by male birds to attract a mate or to define and defend a territory (compare "call").
Speciation --The process through which new species evolve from those in existence.
Sphagnum moss --Any of several mosses of the genus Sphagnum that grow in wet, acidic areas and whose decomposed remains form peat.
Staging area --Place where large numbers of birds traditionally gather en route to breeding or sometimes wintering areas, where they feed and/or roost before continuing onward.
Stoop --Characteristic aerial plunge of some falcons onto prey below.
Subadult --A bird that has not yet acquired definitive adult plumage but no longer has juvenal plumage.
Subarctic --Area just below the Arctic Circle characterized by acidic soils and taiga forest vegetation.
Submalar mark --Or submalar stripe; mark or line of contrastingly dark plumage between the malar and the throat feathers.
Subterminal band --The next-to-last tail band, adjacent to the terminal band.
Subtropical --Relating to areas adjacent to the tropics where summers are hot but winters are nontropical (southernmost Florida and southernmost Texas are the only subtropical regions in the United States).
Succession --The gradual development of an ecosystem caused by changes in community composition.
Supercilium --Area between the lower edge of the crown and the eye line, often contrasting in color with both.
Swamp woods --Type of freshwater wetland, often found along the floodplains of large rivers, that is filled with water most or all of the year.
Taiga --Also called "boreal forest"; continuous belt of subarctic coniferous forest just below the tundra, in North America extending mostly from Alaska to eastern Canada.
Tailband --Contrastingly pigmented area of the tail, perpendicular to the axis of the tail.
Tallgrass prairie --Grassland ecosystem of tall grasses (such as big bluestem, little bluestem, indiangrass, and switchgrass), once extending for tens of millions of acres from the Dakotas to Texas and east through Illinois, but now found only in tiny remnants.
Talon --Claw of a bird of prey.
Tamaulipan brushlands --Ecosystem of the lower Rio Grande valley delta of southern Texas and northeastern Mexico (state of Tamaulipas), characterized by dense, thorny vegetation, mostly stunted trees and spiny shrubs.
Taxon -- (plural: taxa)Broadly, a taxonomic category or group, such as a phylum, order, family, genus, or species; in this guide, "taxa" is often used as shorthand to refer to different subspecies.
Terminal band --Outermost tail band, at the tail's tip.
Territoriality --Behavior pattern in birds concerned with the occupation and defense of a territory, often characterized by intensive singing and clashes with rivals.
Territory --Area occupied by a single bird, mated pair, or group and often vigorously defended against intruders, especially those of the same species.
Tertials --Innermost secondaries (normally 3) that often have a different shape than other secondaries and are sometimes molted on a different schedule.
Thorn scrub --Dry habitat characterized by low-growing thorny vegetation.
Thorn woods --Any habitat where thorny trees dominate, usually in arid regions.
Throat --Area of the underparts bounded by the malars and the breast.
Tideline --Area where two different water masses or currents meet, often concentrating nutrients, prey items, and flotsam.
Tree line --The elevation in a mountainous region above which trees do not grow or the northern (or southern) latitude beyond which trees do not grow; also called "timberline."
Tremolo --Rapid repetition of a single tone with a tremulous quality, similar to vibrato in human singing.
Tropics --The region of earth centered on the equator and lying between the Tropics of Capricorn and Cancer.
Tundra --In North America, the area north of the tree line in Canada and Alaska vegetated with low shrubs, dwarf heath shrubs, cottongrass communities, and various wetlands.
Vagrant --Bird found outside its normal range, especially one quite far out of range.
Vent --Opening through which waste and reproductive products pass in birds; also the plumage located around this area between the legs.
Ventral --In birds, relating to the lower surface of the body from chin to undertail coverts.
Wetland --Low-lying area, such as a marsh or swamp, that is saturated with moisture for at least some period of time during a year or cycle.
Wing bar --Line of contrastingly pigmented (usually pale) plumage formed by the tips of the upperwing coverts, usually the median and/or greater coverts; many species of birds have two wing bars per wing.
Wing-loading --The weight of a bird divided by its wing area.
Wing stripe --Contrastingly pigmented (usually pale) lengthwise stripe on the upper surface of the extended wing, usually formed by the bases of the remiges (compare "carpal bar").
Wrist --Synonym for "carpal joint."