Yellow-Billed Stork

scientific name

Mycteria ibis

size

Bill. 205-242
Tail Length. 168-183
Tarsus. 197-229
Wing. 455-513
Wingspan. 1500-1650
sexes alike • female slightly smaller

characteristics

Adaptations/Coloration. male adult forehead & face naked & hindcrown & neck grayish white • back, upper wing-covert, under wing-covert, breast, & belly white - more or less tinged pink with pinkish or reddish tips to some feathers • wing feathers & tail black • bill bright yellow • face bare skin orange-red • eyes gray-brown • legs red • breeding colors intensify - bill deeper yellow, face bare skin bright red, white plumage suffused pink, & wing-coverts broadly tipped crimson
Bill. long • slightly decurved • thick at base
Feeding. remarkable adaptation • involves quickest known muscular reflex • allows almost all food caught in water
Neck. outstretched in flight
Tail. short • not wedge-shaped
Voice. generally silent • adults bill-clatter with very hollow sound • at breeding colonies "fizzing" whining call or hissing screams (resemble squeaking hinge) • young beg with repeated monotonous braying

behavior

Activity. inactive • rests day • squat on tarsi
Feeding. slightly open bill immersed to near base • stirs bottom mud with one foot • may open wing to shade water • bill instantly snaps when prey moves • may also walk along, plunging bill repeatedly into water & weeds, snapping any prey located • seized prey manipulated, wriggling, between mandibles, then swallowed (usually alive)
Flight. strong quick wing-beats • thermals for far travel
Flock. never very large • usually found in large swamps, along lake margins, larger rivers, irrigated rice fields, & other large areas of marsh & water • may occur at small pools & streams, but not for long • often associates with other storks, herons, & pelicans at favored resting places
Movement. slow • deliberate • exception = when threatening others
Personality. gregarious (usually)
Roosts. ground, sandbanks, lake margins, & sometimes favorite trees nightly

reproduction/life span

Courtship. female approaches "display preens"
Nest. male chooses site • both build in 7-10 days • normally in trees (usually tall acacias & baobobs) • located high up or on top, low trees acceptable in flooded areas • small & large colonies • often & usually with other storks, herons, &cormorants, singly & small groups • maximum 10-20 per tree
Incubation. period not recorded • c. 30 days
Hatching. intervals of 2+ days
Eggs. 2-3 (maybe 4) • laid alternate days
Newborn. helpless • can’t stand • require continuous brooding at first • at 10 days 2nd down emerges & becomes pure white • fledgling period c. 55 days • further good details lacking

diet

Wild. crustaceans, frogs, small fish, some aquatic insects, perhaps small mammals, & worms

habitat/range

permanently present in Zambia, Zimbabwe, & most tropical East Africa
Movements. irregular • somewhat nomadic • poorly documented • East Africa, moves locally • West Africa, regularly migrates south in dry season & north in wet season • South Africa, definitely migrant, arrives in Oct & leaves Apr, remaining through southern summer • resident widespread in aquatic habitats, including alkaline lakes & marine mudflats throughout tropical Africa & less in forested areas • elsewhere, may move locally • some areas, permanent resident, though probably congregate locally to breed

other

can be confused with White Stork (Ciconia ciconia) but adults normally show some pink in plumage & in flight black tail diagnostic

oregon zoo exhibit

Africa Rain Forest