Climate change is blamed for heat stress deaths, disease and range contractions for the Carnaby’s black cockatoo, Calyptorhynchus latirostris, according to a piece in yesterday’s Canberra Times.

During January 2010,  as temperatures soared up to 53 degrees Celsius in  parts of their south-western Australian range, 200 of these endangered cockatoos died. Temperatures beyond 36 degrees leave the birds panting on roosts in trees, unable to forage.

Tests ruled out some alternate causes of death including pesticides, heavy metals and other chemical poisons.  There are no tests to unambiguously demonstrate death from heat stress, but this is strongly implicated in the birds’ death.

Changes to this gregarious bird’s  breeding schedule are also creating problems, according former CSIRO chief research scientist Denis Saunders, who has studied the birds for more than 40 years.  Carnaby’s cockatoos typically began nesting in winter, to allow hatchlings to emerge in spring when food is abundant.  But Saunders told the Canberra Times that nesting times are more varied now that   conditions are hotter and drier. This means some young birds are still in their nests in February,  when adults are unable to forage. In these cases, young are likely to starve, Saunders says.

The birds also appear to be losing their range of suitable climate. Saunders and his colleagues expect to publish a paper in the journal Pacific Conservation Biology later this year demonstrating a southward contraction of the birds’ range toward the Indian and Southern Oceans as aridity increases.  Ultimately, he argues, the birds would be squeezed off the Australian continent.

Habitat fragmentation and loss has long been a major threat to these cockatoos, particularly where nesting hollows are lost in the eucalypt woodlands they favour for breeding. Poaching and invasive species also take a toll. Populations of these gregarious, long-lived cockatoos have likely dropped 50% in the past 45 years. Exact numbers are not known, but Birdlife International estimates their population to be around 40,000 individuals.

Sources:

Saunders et al. (2011) The Impact of Two Extreme Weather Events and Other Causes of Death on Carnaby’s Black Cockatoo. Pacific Conservation Biology, 17(2).
Black cockatoos hard hit by climate change.  22 June 2011. Canberra Times.
Blistering heat blamed for deaths of Carnaby cockatoos. 29 January 2010. Courier Mail.
Birds Australia: Carnaby’s black cockatoo recovery 
BirdLife International (2011) Species  factsheet:Calyptorhynchus latirostris

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