The Ethiopian
Bushcrow - Zavattariornis stresemanni - also known as Stresemann's
Bushcrow, has a restricted range, being confined to thorn acacia country in
southern Ethiopia.
It can be curiously absent from apparently suitable country near these areas. The
reasons for this have not been apparent.
A new study shows
the globally threatened bird’s range exactly follows the edge a unique bubble
of cool, dry climate. Lead author of the study from BirdLife’s UK Partner RSPB,
Dr Paul Donald, is delighted he finally has some answers. “The mystery
surrounding this bird and its odd behaviour has stumped scientists for decades
– many have looked and failed to find an answer. But the reason they
failed, we now believe, is that they were looking for a barrier invisible to
the human eye, like a glass wall. Inside the ‘climate bubble’, where the
average temperature is less than 20°C, the bush-crow is almost
everywhere. Outside, where the average temperature hits 20°C or more,
there are no bush-crows at all. A cool bird, that appears to like staying
that way.”
The reason this
species is so completely trapped inside its little bubble is as yet unknown,
but it seems likely that it is physically limited by temperature – either the
adults, or more likely its chicks, simply cannot survive outside the bubble,
even though there are thousands of square miles of identical habitat all around.
“Whatever the
reason this bird is confined to a bubble, alarm bells are now ringing
loudly. The storm of climate change threatens to swamp the bush-crow’s
little climatic lifeboat – and once it’s gone, it’s gone for good.”
The Ethiopian Bushcrow
Description
The head, mantle,
scapulars, back, rump, and uppertail coverts are all a pale grey. The forehead,
upper ear-coverts, and throat are white. Sexes are similar. The bird's black
bill decurves into a sharply pointed tip, the eyes are black with bright azure
skin around and black legs.
Call
A vocal species, the
main contact call a single metallic "kej", while flying frequent
calls a rapid "kerr kerr kerr".
Food
They feed both on
the ground and in trees. It eats primarily invertebrates and specifically
insects, termites and moths.
Breeding
They nest in a
small, loosely connected colony of three to five nests. The female lays its
eggs shortly after the first rains, which normally occur in late February and
early March. Three to six cream coloured eggs are laid.
Conservation Status – Endangered
The IUCN Red List
of Threatened Species this bird as endangered because of its very restricted
range and loss of suitable habitat. The population seems to be declining
rapidly and in 2007 it was estimated that there might be fewer than 10,000
birds remaining
Birdwatching
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