G Glossary of bird terms

the gape flange on juvenile house sparrow yellowish region @ base of beak.



gape
the interior of open mouth of bird. width of gape can factor in choice of food.
gape flange
the region upper , lower mandibles join @ base of beak. when born, chick s gape flanges fleshy. grows fledgling, gape flanges remain swollen , can used recognize particular bird young.
gizzard
also ventriculus; gastric mill; gigerium. specialized stomach organ found in digestive tract of birds constructed of thick muscular walls used grinding food, aided particles of stone or grit. birds gizzards swallow food , store in crop if necessary. food passes secretory part of stomach (called glandular stomach, , proventriculus or true stomach ). food passes gizzard can ground swallowed stones , passed true stomach, , vice versa. bird gizzards lined tough layer made of carbohydrate-protein complex called koilin, protects muscles in gizzard.
gleaning



specialized cases: foliage gleaning; hover-gleaning; crevice-gleaning. strategy of gleaning on surfaces birds catch invertebrate prey, chiefly insects , other arthropods, plucking them foliage or ground, crevices such rock faces , under eaves of houses or even, in case of ticks , lice, living animals. when gleaning leaves , branches of trees , shrubs called foliage gleaning , can involve variety of styles , maneuvers. birds, such common chiffchaff of eurasia , wilson s warbler of north america, feed actively , appear energetic. hover in air near twig while gleaning it; behaviour called hover-gleaning . other birds more methodical in approach gleaning, seeming lethargic perch upon , deliberately pick on foliage. behaviour characteristic of bay-breasted warbler , many vireos. tactic hang upside-down tips of branches glean undersides of leaves. tits such familiar black-capped chickadee observed feeding in manner. birds, ruby-crowned kinglet use combination of these tactics. crevice-gleaning niche particular dry , rocky habitats. gleaning birds typically small compact bodies , have small, sharply pointed beaks. birds specialize in particular niche, such particular stratum of forest or type of vegetation.
gnathotheca
the rhamphotheca (thin horny sheath of keratin) covering lower mandible.
gonys



the ventral ridge of lower mandible, created junction of bone s 2 rami, or lateral plates. further information: gonydeal angle , gonydeal spot.
gonydeal angle



also gonydeal expansion. proximal end of junction created gonys 2 rami, or lateral plates—the place 2 plates separate. size , shape of gonydeal angle can useful in identifying between otherwise similar species.
gonydeal spot



the spot near gonydeal expansion, in adults of many bird species in gulls, reddish or orangish in colour, triggers begging behaviour. gull chicks, example, peck @ spot on parent s bill, in turn stimulates parent regurgitate food.


male costa s hummingbird (calypte costae) iridescent gorget



gorget
a patch of coloured feathers found on throat or upper breast of species of birds. feature found on many male hummingbirds, particularly found in north america, gorgets typically iridescent. other species have gorgets, such purple-throated fruitcrow , chukar partridge. term derived gorget used in military armor protect throat.
grooming
see entry preening.
gular region
the posterior part of underside of bird s head, described continuation of chin imaginary line drawn between angles of jaw . see also: gular skin.
gular skin
also defined herewith, gular sac / throat sac; gular pouch; gular flutter. describes gular region when featherless. in many species, gular skin forms flap, or gular pouch, used store fish , other prey while hunting. in many others, such frigatebirds, gular skin may overlie sac—the gular sac or throat sac—that may dramatically inflated males during courtship display. in species gular region used thermoregulation, fluttering of hyoid bone , surrounding muscles, vibrating many 735 times per minute, causes increase in heat dissipation gular skin.