ORNITHOLOGICAL GLOSSARY

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

adaptive radiation

Diversification of a single type of organism into multiple types each adapted to a specialized environmental niche.

adaptive radiation Carduelis tristis

air sacs

A set of thin-walled chamber that allow air to flow in a continuous direction in the lungs. The air sacs are depicted in blue.

airfoil

A wing or other structure designed (or evolved) to provide lift and control in flight.

albino

An animal lacking in pigments resulting in white feathers and reddish soft parts.

American Robin Turdus migratorius

allopreening

Mutual preening between two birds.

Burrowing Owl Athene cunicularia

alternate plumage

Breeding plumage or nuptial plumage.

Magnolia Warbler Setophaga magnolia

altricial

Born helpless, often naked with eyes closed.

Palm Warbler Setophaga palmarum

alula

Three to five feathers in wrist of the wing that are used in slow flight or landing, much as slots on an airplane.

Rock Pigeon Columba livia

anisodactlyl feet

Most common pattern of bird toes, with the hallux pointing to the rear and three toes pointing forward.

Peregrine Falcon Falco peregrinus

aposematic

A warning signal that advertises the unpalatablity of a bird or other animal.

Black-headed Pitohui Pitohui dichrous

auricular

Area around the ear opening on the side of a bird’s head. Note blue auricular feathers above.

Green Violetear Colibri thalassinus

axillary

Area between the body and ventral surface of the wing. Note black axillary feathers in Black-bellied Plover

Black-bellied Plover Pluvialis squatarola

basic plumage

Non-breeding or winter plumage - typically duller colored

Magnolia Warbler Setophaga magnolia

belly

The ventral part of the bird below the breast and above the legs. Above, it is the red area above the legs.

Red-bellied Grackle Hypopyrrhus pyrohypogaster

bill

The beak

Golden-collared Toucanet Selenidera reinwardtii

bill-wiping

The behavior of birds wiping the bill clean of sticky food or other substances after feeding

American Robin Turdus migratorius

binocular vision

Three-dimensional vision resulting from overlapping fields of vision due to placement of the eyes facing forward

Luzon Scops-Owl Otus longicornis

booming sacs

Inflatable offshoots of the esophagus covered with bright-colored skin used in courtship display

Greater Sage-Grouse Centrocercus urophasianus

bounding flight

Undulating flight pattern with short bursts of flapping followed by wings folded against the body

bower

A structure built by males of certain promiscuous species to attract females

Gardener Bowerbird Amblyornis inornatus

breast

The chest - the area between the throat andbelly. The blue in the front of this kingfisher corresponds to the area of the breast.

Blue-breasted Kingfisher Halcyon malimbica

bristles

Stiff feathers without vanes or barbules

bronchi

The air passageway that transports air from the trachea to the lungs

brood

The young birds derived from one clutch of eggs

Mute Swan Cygnus olor

brood parasite

A bird that lays its egg in the nest of another bird. Cowbirds and Old World cuckoos are the most familiar examples.

Bronzed Cowbird Molothrus aeneus

brood patch

A highly vascularized, featherless area on the belly of incubating birds

Large-billed Blue-Flycatcher Cyornis caerulata

camouflage

Use of features that blend in with the environment to hide

Little Bittern Ixobrychus minutus

carotenoid

Organic pigments derived from plants and used by birds to color feathers and soft parts

Holub's Golden Weaver Ploceus xanthops

casques

Hollow, bony extension of the skull in hornbills, such as in some hornbills and cassowaries.

Great Hornbill Buceros bicornis

cavity nest

A nest in a hole in a tree, bank, or the ground

Hyacinth Macaw Anodorhynchus hyacinthinus

central fovea

An area of densely packed cells near the center of the retina that perceives sharper images

cere

Leathery skin around the nostrils in birds such as hawks and pigeons

Plumbeous Forest-Falcon Micrastur plumbeus

chin

A small area directly behind the mandible

White-chinned Petrel Procellaria aequinoctialis

choacal protuberance

Enlargement of the cloacal region in some birds during breeding season, caused by the swelling of tubules that store sperm

choana

An opening in the roof of the mouth that leads to the two nasal cavities

clay lick

An area of clay visited by birds, which eat the clay for its mineral content

Dusky-headed Parakeet Aratinga weddellii

cline

A gradual change in characters of members of the same species along a gradient of environmental or geographical transition

cloaca

Common opening for excretory, urinary, and reproductive systems

Gentoo Penguin Pygoscelis papua

cloacal bursa

An organ off of the cloaca, active in young birds, that produces B cells, specialized white blood cells

clutch

The set of eggs laid by a single female during one bout of nesting. Here is a clutch size of four.

American Robin Turdus migratorius

coevolution

Reciprocal adaptations evolved by two or more organisms in response to changes in the other species

colony

A group of birds nesting together

Black-browed Albatross Thalassarche melanophris

comb

A fleshy growth on the top of the head, especially in chickens

commensal

A relationship between to animals that helps one species while being neither a help or hindrance to the other

Cattle Egret Bubulcus ibis

communal roost

A site used by large numbers of birds to sleep

Cattle Egret Bubulcus ibis

cones

Color sensitive cells in the retina

contour feathers

The typical feathers covering a bird with a long central shaft and a broad vane

Wild Turkey Meleagris gallopavo

convergent evolution

A situation where two unrelated species evolve similar features because of similar environments. Example: Yellow-throated Longclaw from Africa and Eastern Meadowlark from the Americas.

Yellow-throated Longclaw Macronyx croceus

cooperative foraging

A feeding strategy in which individuals in a group benefit by working together to catch prey

American White Pelican Pelecanus erythrorhynchos

coracoid

Bone connecting the sternum to the shoulder

courtship display

Ritualized posturing and movements used mostly by males, or both sexes together, to attract mates

Western Grebe Aechmophorus occidentalis

courtship feeding

Transfer of food from the male to the female during courtship and early stages of nesting

Gull-billed Tern Gelochelidon nilotica

coverts

Feathers that overlap wing or tail feathers, covering the base of those feathers

Yellow-billed Stork Mycteria ibis

crèche

A group of bird chicks from different broods attended by a smaller number of adults, freeing other parents to forage

Emperor Penguin Aptenodytes forsteri

crepuscular

Active at dusk or dawn

European Nightjar Caprimulgus europaeus

crop

A sac off of the esophagus used to store food

Harris's Hawk Parabuteo unicinctus

crop milk

Liquid protein from cells grown in a pigeon's crop. Also known as pigeon milk.

Mourning Dove Zenaida macroura

crown

The top of a birds head

Blue-crowned Manakin Lepidothrix coronata

cup nest

An open nest with a shape like a teacup minus the handle

Hooded Warbler Setophaga citrina

decurved

Curved in a downward fashion

Long-billed Curlew Numenius americanus

disjunct range

An area of distribution for an organism that is separate from the main area of distribution

distraction display

Actions taken by a parent bird, such as feigning a broken wing, or acting uncoordinated to distract a predator from the nest or chicks

Killdeer Charadrius vociferus

#N/A

down feathers

Fluffy, soft feathers of young birds or similar feathers beneath the contour feathers of some adult birds

drag

The force that resists movement through the air

drumming

The beating of the wings by a grouse during courtship causing the air to make a thumping sound. Also the rapid hammering of a woodpecker to create a sound proclaiming its territory

Ruffed Grouse Bonasa umbellus

dust-bathing

Crouching and fluttering in dust or dry dirt to spread fine particles into feathers to get rid of ectoparasites and maintain feathers

Northern Bobwhite Colinus virginianus

dynamic soaring

A mode of flight in which the bird gains energy by repeatedly crossing between air masses with different velocities. Albatrosses, for example, gain lift by repeatedly crossing from the calm of a wave trough to headwinds above the waves.

dynamic soaring

eclipse plumage

A female-like plumage acquired by male ducks and some other birds after breeding

Mallard Anas platyrhynchos

ectoparasite

A parasite that lives on the outside of an animal, such as a tick, mite, or leech

Red-legged Thrush Turdus plumbeus

egg

The reproductive product of a bird

Brown-headed Cowbird Molothrus ater

egg tooth

A small sharp knob near the tip of the beak that helps the chick break open the egg. It falls of or is resorbed within a few days of hatching.

Laughing Gull Leucophaeus atricilla

embryo

The developing chick within an egg

Atlantic Petrel Pterodroma incerta

epaulettes

Bright-colored patches of feathers at the base of a bird's wings

Long-tailed Widowbird Euplectes progne

esophagus

The passageway from the mouth to the stomach

esophagus

external ear

The open of the ear leading to the tympanum or ear drum. In most birds it is shallow and covered with specialized feathers.

Double-wattled Cassowary Casuafalcorius casuarius

eye comb

A bright-colored skin over the eye in some birds such as grouse

Spruce Grouse Falcipennis canadensis

eye ring

A circle of bare skin immediately around the eye

Dagua Thrush Turdus daguae

eyeline

A line created by colored feathers that continues on both sides of the eye

Chipping Sparrow Spizella passerina

feather tracts

Regions of skin where feathers attach, also known as pterylae. Here seen as dark bands on lighter skin.

Painted Bunting Passerina ciris

fecal sac

A membrane covered packet containing the feces and uric acid that is collected from the chick's cloaca by the parent bird

Red-eyed Vireo Vireo olivaceus

femur

The proximal (upper) leg bone

femur

fibula

The smaller of two bones on the shin or calf, familiar to many as the skinny bone in the drumstick

fibula

filoplumes

Fine, vaneless, hairlike feathers that have sensory receptors adjacent to their follicles

Yellow-bellied Bulbul Criniger phaeocephalus

flank

The upper sides of a bird

Hooded Merganser Lophodytes cucullatus

fledgling

A chick that has recently flown from the nest for the first time

White-crowned Pigeon Patagioenas leucocephala

flight feathers

The remiges and retrices--major tail and wing feathers

Egyptian Vulture Neophron percnopterus

flight song

A courtship or territorial song sung in flight

European Sedge-Warbler Acrocephalus schoenobaenus

forehead

The part of the crown just above the beak

Plushcap Catamblyrhynchus diadema

forked tail

A tail with a notch in the center

Fork-tailed Drongo Dicrurus adsimilis

frugivorous

Eating fruit as the major part of the diet

Fawn-breasted Tanager Pipraeidea melanonota

furcula

The fused clavicles of a bird - popularly known as the wishbone

furcula

gape flange

The soft tissue where the two halves of the jaw join--often conspicuous in nestlings and juvenile birds

Ocellated Antbird Phaenostictus mcleannani

gizzard

The muscular section of the avian stomach which grinds food

gizzard

gleaning

Picking prey off of leaves and other surfaces

Swainson's Thrush Catharus ustulatus

glenoid fossa

The rounded depression in the scapula that articulates with the head of the humerus and allows the wing to rotate

glenoid fossa

gliding

Flying without flapping while losing altitude slowly

gliding

globular nest

A spherical nest, typically with the opening on the side

Grosbeak Weaver Amblyospiza albifrons

graduated tail

A tail in which the retrices are progressively longer toward the center

Rose-ringed Parakeet Psittacula krameri

grazing

Feeding on grass and other herbaceous plants

Barnacle Goose Branta leucopsis

greater coverts

The row feathers that lies immediately above the flight feathers (On the shoveler, the white row of feathers above the secondaries and the corresponding row over the primaries)

Northern Shoveler Anas clypeata

guano

The accumulated droppings of colonial birds, especially seabirds. It is mined as fertilizer in some places. Guano covers much of this hill.

Peruvian Booby Sula variegata

guild

A group of birds in one area that exploits resources in a similar fashion. Illus. army ant followers in Panama: A Northern Barred Woodcreeper, B Plain Brown Woodcreeper, C Rufous-vented Ground-Cuckoo, D Ocellated Antbird, E Gray-headed Tanager, F Spotted Antbird, G Bicolored Antbird

guild

gular Sac

Expandable pouch of skin just below the chin which can be used for panting to cool the bird

Double-crested Cormorant Phalacrocorax auritus

hallux

The first toe, usually pointing backwards

Wild Turkey Meleagris gallopavo

hatch

To emerge from the egg

Gentoo Penguin Pygoscelis papua

hatchling

A bird that has just emerged from the egg

Lesser Frigatebird Fregata ariel

hawking

Feeding by flying out from a perch to snatch prey and returning to that perch

hawking

herbivore

An animal that eats plant material exclusively or almost so

Hoatzin Opisthocomus hoazin

heterodactyl foot

A bird foot in which digits three and four face forward, while the first and second digit face backward. Trogons have this pattern.

Masked Trogon Trogon personatus

hooklets

Tiny hooks on the barbules of feathers that keep the barbs and barbules from separating

Hooklets

hover

Flying in a stationary position

Osprey Pandion haliaetus

humerus

The wing bone closest to the body

humerus

hybrid

A cross between two different species

Hybrid Duck Mallard x Pintail A. platyrhynchos x A. acuta

ilium

The largest and uppermost bone in the pelvic girdle. It is fused with the ischium and synsacrum.girdle.

ileum

imprinting

Behaviors that are learned and fixed during a limited critical period in a bird's early life

Upland Goose Chloephaga picta

incubation

Maintaining the eggs at a constant temperature ideal for development. Most birds incubate by sitting on the eggs but megapodes incubate in compost or warm sand.

Least Tern Sternula antillarum

infundibulum

The funnel shaped anterior end of the oviduct that accepts the egg during ovulation

infundibulum

iridescence

Glittering colors that change with the angle of view, caused by structural features of feathers that scatter light. A famiiar example is the feathers on a Rock Pigeon's neck.

Nicobar Pigeon Caloenas nicobarica

iris

The colored circular diaphragm in the eye that controls the amount of light hitting the retina

Semiplumbeous Hawk Leucopternis semiplumbeus

ischium

The large pelvic bone posterior to the leg joint and fused with the posterior portion of the synsacrum

ischium

juvenile

A young bird, usually in the first months after fledging, that has its first set of contour feathers

Herring Gull Larus argentatus

keel

A large, flat ridge of bone that extends perpendicularly from the main portion of the sternum The major flight muscles, the pectoralis and the suprcoracoideus, attach to the keel. Also known as carina.

keel

keratin

A fibrous protein that is the chief component of feathers, scales and claws

Common Poorwill Phalaenoptilus nuttallii

kettle

A group of rising birds soaring in a spiral motion in a thermal

Turkey Vulture Cathartes aura

kleptoparasite

An animal that habitually steals food from another animal

Magnificent Frigatebird Fregata magnificens

lacrimal gland

The structure at the ventral side of the eye that secretes tears

lacrimal glands

laminar flow

Smooth flow of air over the surface of the wing

laminar flow

lek

A communal display ground for promiscuous male birds

Greater Sage-Grouse Centrocercus urophasianus

lens

The hard, transparent area inside the eye that focuses light

lens

lesser coverts

The rows of feathers on the wing immediately over the greater coverts

African Pygmy Kingfisher Ispidina picta

lore

The area between the eye and the beak--chartreuse on this breeding Great Egret

Great Egret Ardea alba

malar region

The lower part of the face extending behind the lower beak, seen here in black on this Northern Flicker

Northern Flicker Colaptes auratus

mandible

The lower half of the beak

Black Skimmer Rynchops niger

melanism

Darkening of pigmented feathers due to extra melanin (a class of pigments) , in this case making a normally white Cattle Egret, blackish

Cattle Egret Bubulcus ibis

mesobronchus

The extension of the bronchus inside the lungs leading to the abdominal air sacs

mesobronchi

metacarpals

The three bones that fuse to form the carpometacarpus distal to the humerus

metacarpal

migration

Seasonal movement of birds from one area to another

American White Pelican Pelecanus erythrorhynchos

mimicry

In birds, most often used for vocal mimicry, in which one species imitates the vocalizations of another. Mockingbirds are "open-ended" learners and can add new songs to their repetoire thoughout their life.

Northern Mockingbird Mimus polyglottos

molt

Periodic loss and regrowth of feathers. This Ring-billed Gull shows wing molt.

Ring-billed Gull Larus delawarensis

monocular vision

Sight in which each eye is used separately with little overlap in the field of view of each eye

American Woodcock Scolopax minor

monogamy

Maintaining a single mate, at least for the duration of nesting

Scarlet Macaw Ara macao

morph

Groups of birds that differ in body size, bill shape, color or other features from other groups of birds of the same species. The two color morphs of Reddish egrets shown here.

Reddish Egret Egretta rufescens

mound nest

A nest made from a heap of sand, sticks or other material with an egg chamber inside, particularly those of the moundbuilders

Mallee Fowl Leipoa ocellata

mycoplasmal conjunctivitis

A disease, most commonly observed in House Finches, in which the eye is swollen, crusty and sometimes shut

House Finch Haemorhous mexicanus

nape

The region at the back of the neck

Yellow-naped Parrot Amazona auropalliata

nares

The external openings of the nose

Turkey Vulture Cathartes aura

natal down

Loose, fluffy feathers of young birds prior to developing contour feathers

Whiskered Tern Chlidonias hybrida

nest

The structure in which a bird lays and incubates its eggs

Black-browed Albatross Thalassarche melanophris

nest appropriation

Using the nest of another bird, typically after the other bird has ceased to use it. This horned owl has appropriated a hawk nest.

Great Horned Owl Bubo virginianus

nictitating membrane

A transparent membrane that slides sideways over the eye, moistening or protecting it

Red-headed Vulture Sarcogyps calvus

nidifugous

Leaving the nest shortly after hatching

Dunlin Calidris alpina

nocturnal

Active at night

Eastern Screech-Owl Megascops asio

oil gland

A sebaceous gland near the dorsal base of the tail that produces oil for preening, also known as uropygial gland or preen gland

Black-crowned Night-Heron Nycticorax nycticorax

omnivore

An animal that eats both plant and animal material

Gila Woodpecker Melanerpes uropygialis

operculum

A structure that covers the nares in some birds

Rock Pigeon Columba livia

oral flanges

See gape flanges

Canyon Wren Catherpes mexicanus

oviduct

The long, convoluted tube through which the egg passes from ovary to cloaca. Albumin, membranes and egg shell are added in the oviduct.

oviduct

pamprodactyl feet

Feet with toes all arranged in a forward orientation, as in some swifts

Chimney Swift Chaetura pelagica

pecten

A comb-shaped structure of blood vessels inside the avian eye extending out from the optic nerve. It is thought to nourish the retina and control the ph of the vitreous humor.

pecten

pectinate claw

A claw with a comb-like edge found in heron family and in nightjars and Barn Owls. It is presumably used for preening.

Tricolored Heron Egretta tricolor

pectoral girdle

The bones connecting the wing with the main part of the skeleton. It consists of the furcula, scapulas , coracoids , and sternum.

pectoral girdle

pectoralis

The large breast muscle that powers the downstroke of flight by depressing the wing at the shoulder

pectoralis major

pelagic species

A bird that spends its life on the open ocean. Pelagic birds typically only coming to land to breed.

Pink-footed Shearwater Puffinus creatopus

pellet

The regurgitated bolus of indigestible prey parts expelled by owls, kingfishers and other birds

Snowy Owl Bubo scandiacus

pelvic girdle

The fused ilium, ischium, , pubis, and fused sacral vertebrae. Together they form an anchor for the tail and leg muscles.

pelvic girdle

pendulous cup nest

A sock-shaped nest suspended from twigs, especially by orioles, oropendolas, and caciques.

Crested Oropendola Psarocolius decumanus

pensile cup nest

A cuplike nest suspending by the rim typical of vireos, some blackbirds, and kinglets.

Warbling Vireo Vireo gilvus

phalanges

The finger bones--reduced in birds.

phalanges

pigments

Chemical compounds that absorb light of specific wavelengths giving feathers and soft parts their colors.

Scarlet Macaw Ara macao

pin feathers

Growing feathers still covered by the feather sheath

Little Blue Heron Egretta caerulea

pipped

Describing an egg that has a small hole made by a chick about to hatch

American White Pelican Pelecanus erythrorhynchos

piracy

Stealing food from other birds, typically from other species

Brown Noddy Anous stolidus

platform nest

Nests built of sticks piled on each other with a low depression for the eggs

Osprey Pandion haliaetus

plumage

The set of feathers that cover a bird, or a seasonal or age-related pattern of the feathers

Scarlet Tanager Piranga olivacea

plunge diving

Diving from the air into water after prey using momentum to overcome buoyancy. Typical of pelicans, boobies, gannets, and most terns.

Blue-footed Booby Sula nebouxii

pneumatic bones

Hollow bones containing extensions of air sacs. Their light weight makes them an important adaptation for flight.

pneumatic bones

polyandry

A form of polygamy in which a female has more than one male mate at a time

Spotted Sandpiper Actitis macularia

polygamy

A breeding system in which a member of one sex takes multiple mates of the opposite sex

Marsh Wren Cistothorus palustris

polygyny

Mating system in which each male may mate with multiple females

Red-winged Blackbird Agelaius phoeniceus

polymorphism

Two or more different forms (at the same life stage) in the same species, such as two distinct color variations or morphs

Ruff Philomachus pugnax

porphyrins

A group of pigments responsible for certain brown and green feather coloration and in one case magenta

Schalow's Turaco Tauraco schalowi

precocial

Baby birds hatched with down and with eyes open, ready to leave the nest

Canada Goose Branta canadensis

precopulatory display

Ritualized postures and vocalizations uniquely performed prior to copulation

Yellow-headed Blackbird Xanthocephalus xanthocephalus

preening

Cleaning and arranging the feathers typically with the beak

White Ibis Eudocimus albus

premaxilla

The main bone of the upper half of the beak

premaxilla

primaries

Flight feathers attached to the outermost segment of the wing. In the Palm Nut Vulture they have white bases.

Palm-nut Vulture Gypohierax angolensis

promiscuous

Describing a species in which one sex breeds with multiple mates

Greater Sage-Grouse Centrocercus urophasianus

proventriculus

The glandular chamber of the avian stomach between the esophagus and the gizzard

proventriculus

pupil

The opening in the center of the eye, through which light passes

Scale-feathered Cuckoo Lepidogrammus cumingi

pygostyle

The last bone at the posterior end of the vertebral column, which supports the tail feathers and related musculature. It is formed by several fused vertebrae.

pygostyle

rachis

The outer portion of the shaft (central support) of the feather that supports the vanes

Canada Goose Branta canadensis

radius

The smaller of paired bones in the middle section of the wing

radius

recurved

Curved upwards, as in the beak of an avocet

American Avocet Recurvirostra americana

remiges

The flight feathers of the wing -- the primaries and secondaries combined

Greater Scaup Aythya marila

retort nest

A globular nest with an entrance tunnel

Lesser Masked Weaver Ploceus intermedius

retrices

The major feathers of the tail

Red-tailed Hawk Buteo jamaicensis

rhamphotheca

A horny sheath of keratin that covers the beak

rhampotheca

rictal bristles

Stiff whisker-like feathers around the gape, most commonly found in aerial feeders, which presumably help to guide food into the mouth

Tawny-breasted Flycatcher Myiobius villosus

rump

The region between the back and the tail on the dorsal side of the bird

Scarlet-rumped Cacique Cacicus uropygialis

sacral vertebrae

Vertebrae just anterior to the caudal vertebrae, which are fused as part of the synsacrum

sacral vertebrae

salt gland

An organ for excreting excess salt found in seabirds, located above or in front of the eye

salt gland

sap well

A hole drilled in bark by a sapsucker that allows sap to collect. The woodpecker returns periodically to the well to drink the sap and eat any insects attracted to it.

Yellow-bellied Sapsucker Sphyrapicus varius

scapula

The shoulder blade

scapula

scapulars

Feathers at the base of the wing lying at the side of the back and often covering the folded wing

Greater Flamingo Phoenicopterus roseus

scavengers

Animals that feed on dead and decaying plants and animals

White-backed Vulture Gyps africanus

scleral ossicles

A ring of bones that supports the eye

scleral ossicles

scrape

A shallow depression in the ground made by a bird to use as a nest

Least Tern Sternula antillarum

secondaries

Flight feathers that attach to the ulna (forearm) inward from the primaries

Steller's Eider Polysticta stelleri

slots

Spaces between the primary feathers of certain birds such as vultures that allow individual feathers to act as airfoils and reduce turbulence

Turkey Vulture Cathartes aura

soaring

Sailing on outstretched wings without flapping or losing altitude

Bald Eagle Haliaeetus leucocephalus

songs

Complex vocalizations communicating territoriality or advertising for a mate

Blue-winged Warbler Vermivora pinus

speculum

A patch of bright feathers on the secodaries of certain ducks' wings

Mallard Anas platyrhynchos

spread-wing posture

Perched stance with wings outspread

Double-crested Cormorant Phalacrocorax auritus

spur

A bony spike on the wing or tarsus certain birds, such as jacanas, screamers, pheasants, and spurfowl

Yellow-necked Spurfowl Francolinus leucoscepus

sternum

The breastbone - the site of attachment for the major flight muscles and the ribs

sternum

structural colors

Coloration resulting from light scattering due to the physical structure of feathers

Magnificent Hummingbird Eugenes fulgens

subadult

A bird past the juvenile stage that has not reached maturity

Bald Eagle Haliaeetus leucocephalus

sunning

Posturing to catch solar radiation

Groove-billed Ani Crotophaga sulcirostris

supracoracoideus

The muscle that powers the upstroke of the wing. It attaches to the sternum and the humerus.

supracoracoideous

surface diving

Diving beneath the water, starting at a swimming position

Horned Grebe Podiceps auritus

syndactyl feet

Feet with the outer and middle toes fused for most of the length, such as in kingfishers and hornbills

Rufous Hornbill Buceros hydrocorax

syringeal muscles

Muscles that modulate the voice by controlling the shape of the syrinx (avian voice box)

syringeal muscles

tarsometatarsus

The outermost of the three long leg bones in a bird. It is homologous to ankle and foot bones of mammals.

tarsometatarsus

tarsus

Alternate name for the tarsometatarsus and also for that region of the leg

Herring Gull Larus argentatus

temporal fovea

An area of concentrated receptor cells in the retina toward the side of the head. It increases the depth perception in hawks, terns parrots, swallows and doves.