Sula (or papsula) abbotti
status: Critically endangered, IUCN Endangered, ESA
range: Christmas Island
Description and biology
Booby is the common name for a large seabird that inhabits tropical waters. Those members of the same family that inhabit northern waters are called gannets. The Abbott's booby measures 31 inches (79 centimeters) long and weighs about 3 pounds (1.4 kilograms). It has a wingspan of almost 6 feet (1.8 meters). The female is slightly larger than the male. This booby is black and white in color and has a saw-toothed bill that is gray in males and pink in females. During greeting and courtship, the bird emits a distinctive deep, loud call.
The Abbott's booby is the only member of its family that builds its large, bulky nest at the top of a tall tree instead of on the ground. Females of the species lay one very large white egg between May and June. They incubate (sit on or brood) the egg for 42 to 55 days before it hatches. Both mother and father care for the chick, which is quite helpless for the first three weeks. It grows slowly and does not take its first flight
until it is five or six months old. After about one year, the chick finally flies out to open sea.
Like other boobies and gannets, the Abbott's booby feeds on fish and squid. The bird dives after its prey from great heights and will often chase it underwater. Air sacs under the booby's skin help soften the impact when it hits the water; they also help the bird to float. The average life span for the Abbott's booby is 25 to 30 years.
Habitat and current distribution
The Abbott's booby nests only on Christmas Island (territory of Australia), a tiny island in the Indian Ocean lying roughly 200 miles (320 kilometers) south of the island of Java (part of Indonesia). Biologists (people who study living organisms) estimate that about 2,000 male-female pairs currently exist.
The birds prefer to build their nests at the top of very tall rain forest trees on the island's western plateau. They generally feed at sea northwest of the island.
History and conservation measures
Boobies were so-named because of their rather dull facial expression and their extreme tameness. They are easily approached by humans, a factor that led to their early decline. When sailors and early settlers on the island began hunting Abbott's boobies, they merely walked up to the birds and clubbed them to death.
The main threat to the Abbott's booby for decades has been deforestation. In order to mine underground phosphate (mineral salt) deposits, humans on Christmas Island have clear-cut a vast majority of mature trees in the booby's habitat. Since 1987, mining activities have been limited to those areas already cleared of trees. Attempts have been made to reforest some areas and to establish a national park where the Abbott's booby would be protected, but replanting a rain forest takes a long time and the species reproduces at a very slow rate.
A new threat to the booby is the yellow crazy ant (Anoplolepis gracilipes). The ant, which is native to Africa, was introduced to Christmas Island early in the twentieth century and it became widespread. The crazy ants have wiped out the red crab population of Christmas Island. The red crab was essential to the ecosystem because it ate weed seedlings and leaves, keeping the balance in the rain forest. Scientists predict that unless the yellow crazy ant is eliminated, it will cause a rapid reduction in the population of Abbott's boobies over the next three generations.