An updated assessment of a rare, rainforest-dwelling eagle confirms the species is critically endangered. But the new insights on its habitat could help bring the bird back from the brink.
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| There are only about 800 Philippine eagles left, according to the latest survey of their numbers Klaus Nigge/Philippine Eagle Foundation |
Found only on the four major islands of the Philippines, Philippine eagles (Pithecophaga jefferyi) are one of the largest living eagle species – about a metre long and heavier than a bowling ball. They hunt everything from monkeys to large monitor lizards. Due to deforestation and shooting by humans, the eagles are also among the world’s most imperilled raptors, and considered critically endangered by the International Union for Conservation of Nature, the most severe extinction risk category before animals are no longer found in the wild.
Yet while enough is known about Philippine eagles to conclude that they are in grave peril, researchers have very little detail about their range and habitat needs. That is largely thanks to their sparse numbers in remote, hard-to-access forest habitats, says Chris McClure at The Peregrine Fund in Idaho.
“There are literally gaps in the map where we don’t know whether or not the species exists,” he says.
Additionally, says Jayson Ibañez at the Philippine Eagle Foundation in the Philippines, his organisation hadn’t conducted any eagle population estimations since the early 2000s.
To help fill these knowledge gaps, the Philippine Eagle Foundation partnered with the Peregrine Fund, updating the raptor’s estimated range and population size across the entire country.
The researchers used satellite data to determine what regions of forest across the Philippines would be suitable habitat for the eagles. Location and nesting records of dozens of birds on the island of Mindanao helped the team estimate how many territorial breeding pairs of eagles could fit into the available habitat, and where they were likely to thrive. This relationship was extrapolated out to the four major islands the eagles inhabit.
The researchers estimate that forest habitats across the entire country could support just under 800 eagles in total. About one-third of the eagles’ suitable habitat currently sits within protected areas. But since the Philippine eagle requires lots of space to feed and reproduce, the researchers estimate that the species needs at least 45 per cent of its range protected for long-term conservation.
“[The eagle] is indeed as critically endangered as we thought,” says McClure.
But mapping relative habitat quality can be crucial for future conservation efforts.
“Now we have a clear guide on which particular Philippine eagle habitats need to be protected,” says Ibañez. The researchers outline suggested regions for new protections, such as the Apayao Lowland Forest in northern Luzon and the Sibuco and Sirawai regions of western Mindanao.
Since the mapping only shows where eagles have the potential to live, not where they can be found now, it could be used to identify suitable territories for releasing captive raised or rehabilitated eagles into the wild, says McClure.
“If it’s empty habitat, then that’s prime real estate to release a new pair of birds.”
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