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Guam Broadbill / Myiagra
freycineti
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The Guam
Broadbill, also known as "Chuguangguang" in the native language,
was a small bird that had a bluish head and neck with a metallic
luster; a back and upper wing coverts that were near green-blue;
a rump that was grayer than the back; white chin and throat feathers;
light cinnamon breast feathers; bluish-slate tail; black bill and
feet; and dark brown iris. |
Habitat
& Behavior:
The Guam Broadbill was endemic to Guam in the Mariana
Archipelago. This insectivorous species was once found in all habitats
of the island with the exception of southern savannas but is now extinct.
Like other flycatchers in Micronesia, pairs aggressively defended territories
against other birds, and approached and scolded human intruders as well.
The species foraged within the forest, and individuals were rarely seen
outside protective vegetation. The call was a loud series of whistles
which were given fairly commonly during morning hours.
Past
& Present:
Although the species was probably never abundant, reduction
in Guam Broadbill range was noted from 1950 into the early 1980s. Prior
to 1950, the species occupied 310 miles of habitat throughout the island
of Guam. By 1950, Broadbill range had been reduced to 193 miles or 62%
of its former range. By the early 1970s, the species was entirely absent
from the southern two-thirds of the island but still widespread and common
northern Guam into the mid-1970s. Known estimates of 460 birds in 1981
and fewer than 100 individuals in 1983 from the Pajon Basin had dwindled
to only one sighting of a male in October 1983. In 1983, the population
declined 83% in the Ritidian Basin area and was further restricted to
the extreme northern end of Guam in the Pajon Basin.
Reduction in Guam Broadbill range and its eventual extinction has been
attributed to excessive pesticide spraying during and after World War
II, the spread of avian diseases, and predation by introduced animals,
such as the rat, the monitor lizard, and the brown tree snake.
Conservation Efforts:
In 1983, a male Broadbill was collected for captive propagation
but failed as other wild individuals were not located and the captive
male died of unknown causes. By the mid-1980s, the population continued
to decline dramatically from undetermined causes. Studies conducted by
the U.S. Fish and Wildlife Service's (Service) Patuxtent Wildlife Research
Center in 1983 indicated that pesticide overuse and avian diseases were
not responsible for Broadbill declines in the early 1980s. Instead, studies
conducted implicated predation by the brown tree snake as the single most
important factor in the decline of Guam's native forest birds, including
the Guam Broadbill.
The Guam Broadbill has not been seen since May 15, 1984, and was listed
as an endangered species on August 27, 1984. The Service removed the Guam
Broadbill from the Federal List of Endangered and Threatened Wildlife
on February 23, 2004, due to extinction.
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