Ibis

Description:

The white plumage and pink facial skin of adult American White Ibises are distinctive.[10] Adults have black wingtips that are usually only visible in flight.[11] In non-breeding condition the long downcurved bill and long legs are bright red-orange.[12] During the first ten days of the breeding season, the skin darkens to a deep pink on the bill and an almost purple-tinted red on the legs. It then fades to a paler pink, and the tip of the bill becomes blackish.[13] It is difficult to determine the sex of an adult American White Ibis from its external appearance, since the sexes have similar plumage.[14] However, there is sexual dimorphism in size and proportion as males are significantly larger and heavier than females and have longer and stouter bills.[15] A study of the American White Ibis in southern Florida yielded weight ranges of 872.9 to 1,261 g (1.924 to 2.78 lb) for males and 592.7 to 861.3 g (1.307 to 1.899 lb) for females, with average weights of 1,036.4 g (2.285 lb) for males and 764.5 g (1.685 lb) for females.[15][16] The length of adult female and male birds ranges from 53 to 70 cm (21 to 28 in) with a 90 to 105 cm (35 to 41 in) wingspan.[17][18] The newly hatched American White Ibis is covered with gray down feathers, deepening to dark brown or black on the head and wings. The chest is often bare and there can be a white tuft on the head. The irises are brown. The exposed skin is pinkish initially, apart from the tip of the bill which is dark gray, but turns gray within a few days of hatching.[8] The bill is short and straight at birth and has an egg tooth which falls off between days five and nine,[19] and develops three black rings from around day six, before turning gray by around six weeks of age. The gray to sandy gray brown juvenile plumage appears between weeks two and six, and face and bill become pink a few weeks later, while the legs remain gray. The irises have turned slate-gray by this stage.[8] Once fledged, the juvenile American White Ibis has largely brown plumage and only the rump, underwing and underparts are white.[11] The legs become light orange. As it matures, white feathers begin appearing on the back and it undergoes a gradual molt to obtain the white adult plumage.[11] This is mostly complete by the end of the second year, although some brown feathers persist on the head and neck until the end of the third year. Juvenile birds take around two years to reach adult size and weight.[8] Like other species of ibis, the American White Ibis flies with neck and legs outstretched, often in long loose lines or 'V' formations—a 1986 field study in North Carolina noted over 80% of adult ibis doing so, while juveniles rapidly took up the practice over the course of the summer. The resulting improvement in aerodynamics may lower energy expenditure.[20] These lines fly in an undulating pattern as they alternately flap and glide. Soaring in a circular pattern is also seen.[21] Heights of 500 to 1,000 m (1,600 to 3,300 ft) may be reached as birds glide over flights of 20 km (12 mi) or more. More commonly, birds fly between 60 and 100 m (200–350 ft) above the ground, gliding or flapping at a rate of around 3.3 wingbeats a second.[22] The main call of the American White Ibis is a honking sound, transcribed as urnk, urnk,[2] or hunk, hunk.[8] The call is used in flight, courtship or when disturbed. Birds also utter a muted huu-huu-huu call while foraging, and make a squealing call in courtship. Young in the nest give a high-pitched zziu as a begging call.[8]

Habitat:

The American White Ibis is most common in Florida, where over 30,000 have been counted in a single breeding colony. It also occurs throughout the Caribbean, on both coasts of Mexico (from Baja California southwards) and Central America, and as far south as Columbia and Venezuela. The non-breeding range extends further inland, reaching north to Virginia, and west to eastern Texas. The species is known to wander, and has been sighted, sometimes in small flocks, in states far out of its usual range.[5][11] In North America, breeding takes place along the Atlantic coast, from the Carolinas south to Florida and thence west along the Gulf Coast.[2] Laguna Cuyutlán is an isolated and regionally important wetland in the state of Colima on México's west coast where a breeding colony has been recorded.[24] American White Ibises are not faithful to the sites where they breed,[25] and large breeding colonies composed of ten thousand birds or more can congregate and disband in one or two breeding seasons.[26] Breeding populations across its range have fluctuated greatly with wholesale movement between states.[27] Until the 1940s, the species only bred in large numbers in Florida, mostly within the Everglades.[26] Drought conditions elsewhere in the United States led to over 400,000 American White Ibis breeding there in the 1930s.[27] In the 1950s and 1960s, large colonies appeared in Alabama, Louisiana, and then North and South Carolina and the Gulf Coast of Florida, and finally Texas in the 1970s. Then, between the 1970s and early 1990s, breeding colonies declined and disappeared in South Carolina and Florida, and greatly increased in Louisiana,[26] and North Carolina.[27] Colonies last between one and seventeen years, their longevity related to size and quality of nearby wetlands. The longest-lasting are associated with wetlands over 800 km2 (300 mi2) in size. Degradation of wetland or breeding sites are reasons for abandonment.[26] The population of American White Ibises in a colony at Pumpkinseed Island in Georgetown County, South Carolina dropped from 10,000 to zero between 1989 and 1990 as Hurricane Hugo had inundated nearby freshwater foraging areas with salt water.[28] The American White Ibis is found in a variety of habitats, although shallow coastal marshes, wetlands and mangrove swamps are preferred.[29] It is also commonly found in muddy pools, on mudflats and even wet lawns. Populations that are away from the coast and shoreline, particularly in southern Florida, often reside in other forms of wetlands such as marshes, ponds and flooded fields.[2][11] In summer, these move to more coastal and estuarine habitats as inland waterways become flooded with summer rains and the ibis find the water levels too deep to forage effectively