Saturday, 2 February 2013

Black Heron


order : Ciconiiformes      Genus & Species : Ardeidae     Family : Egretta ardesiaca

The black heron employs an unusual hunting method: it spreads its wings like a cape, creating a shade canopy over the water’s surface that lures prey within striking distance. The black heron’s yellow-orange feet turn a rich red during the breeding season; its broad wings are an integral part of its hunting technique. They found in Africa, south of the Sahara, including Guinea, Ivory Coast, Nigeria, Kenya, Tanzania, Zambia, Zimbabwe and South Africa; also on the island of Madagascar. 

Habitat : The black heron is usually found near freshwater throughout its African habitat.This wading bird prefers shallow lakes, rivers, ponds, marshes, flood plains and rice paddies, as well as alkaline lakes, mangroves and tidal flats. The black heron has also been recorded as high as 4,900' above sea level on the high plateaus of Madagascar.This sedentary bird remains within its home territory, where it roosts in tall trees at night and wades in shallow water or mudflats. Breeding grounds, also within the territory, are reused year after year. 
Food & Feeding : The black heron feeds mainly on fish and employs a unique feeding technique — it lures prey to the surface of the water by forming a canopy with its wings. The black heron walks about slowly, intermittently spreading its wings over its head like an umbrella, maintaining this pose for 2–3 seconds. The canopy reduces glare and forms shade — this attracts fish, its favorite prey. The black heron spears a fish with its long, pointy bill, and swallows it whole, usually head first, to avoid the fish’s spiny fins. This bird also feeds on crustaceans and aquatic insects that it stirs up by raking its feet along the muddy bottom. The black heron feeds during the day or at dusk, and then moves off to nighttime communal roosts with other herons, egrets and darters. 
Behavior : The black heron spends a great deal of time on the ground, walking on strong, unwebbed feet. At communal roosts, flocks mix with other species during feeding and rest periods. The black heron is generally quiet except during the breeding season; then, it emits a guttural call, usually during rainy months. When alarmed, the heron emits a low-pitched croak. The black heron preens and grooms itself with its soft powder-down feathers. Using its bill to spread the powder onto its feathers, the black heron then uses the comblike claw on its longer middle toe to remove grease, dirt and fish slime from its plumage. Males and females often engage in mutual cleaning as part of the mating ritual; this serves to strengthen the bond between breeding pairs. 
Breeding : Breeding occurs during the rains and flooding periods, and the male begins to collect nest materials while simultaneously trying to attract a female. Nests are usually scattered in colonies mixed with other herons, egrets or darters. Both sexes’ yelloworange feet turn bright red during courtship.The male stretches on his perch, pointing his head and neck to the sky, inviting the female to take a closer look. After mating, the pair builds a nest of sticks and rocks in trees up to 15' above ground, or in bushes or reed beds near or over water. Both sexes incubate for the 2–4 eggs for 18–30 days. The helpless and blind chicks are covered with a dark-gray down and hatch at different intervals over a one-week period; the adults feed them regurgitated food. Because of the hatching intervals, there is a big difference in the chicks’ size, and the largest chick often gets more food; some late-hatching chicks do not survive. Juveniles resemble adults but have duller plumage and reach maturity in 1–2 years. 

Bill : The straight, daggerlike bill is used to spear fish and snatch crustaceans and insects. 
Eyes : The eyes are located toward the top of the head; this allows the heron to see approaching predators even while feeding with its head down. 
Feathers : Continuously growing downy feathers disintegrate to form powder. Located on the breast and rump, powder downs are used to remove dirt and slime from the rest of the plumage. 
Feet : Strong, unwebbed feet enable the heron to walk great distances while foraging.The middle toe is slightly longer, with comblike serrations used to remove fish slime and mud during grooming. 
Wings : The bird spreads its broad wings to form an umbrella over the water when wading for food. 

Weight : 9.5–14 oz.
Length : 16.5-26"
Wingspan : 35-41" 
Sexual Maturity : 1-2 years
Breeding Season : Varies with location 

The black heron also forages by vibrating its colorful feet in the water; this helps to attract aquatic prey, such as fish and crustaceans.