Harpy eagles in the Amazon may be among the world’s largest and most powerful birds, but they are struggling to feed their young as their habitat is destroyed, researchers warned.
Once common from southern Mexico to Argentina, the total population of harpy eagles has shrunk more than 40 percent since the 19th century, with habitat loss and shooting among the biggest causes.
A new study on the harpy eagles, published on Wednesday in the journal Scientific Reports, shows the devastating impacts humans have brought on the birds, which stay in one nesting site for decades.
Researchers set up cameras and identified bone fragments at 16 eagle nests in the Mato Grosso area of the Brazilian Amazon.
Harpy eagles, with legs almost as thick as a human wrist and claws as big as a hand, feed mainly on sloths and monkeys that they catch in the forests.
Researchers found that eagles cannot find enough food if their territory is deforested more than 50 percent. Eagles starved in their nests in areas of severe forest loss.
Researcher Everton Miranda of the University of KwaZulu-Natal, who led the study, said the birds listed as “near threatened” by the International Union for Conservation of Nature (IUCN) need forest cover and plenty of prey in the trees to thrive.
The apex predators, which weigh up to about 7.3 kilograms (16 pounds) for females and 5.9 kg for males, can live for decades, with one wild-caught individual recorded at 54 years old.
Less food for baby eagles
Their breeding cycle lasts up to a year and a half, during which they lay two eggs, but only one eagle will survive. The eagles are known to breed at the same t-shaped nest tree for several decades, the study said.
In deforested areas, the authors saw that instead of switching to alternative prey, the eagles returned to their nest with their regular food less frequently. Three eaglets starved in landscapes where deforestation was between 50-70 percent.
In areas where the rate of deforestation was over 70 percent, no nests were found. This suggests that broader declines in harpy eagle populations are driven by “prey scarcity derived from habitat loss, which is caused by cattle ranching,” Miranda told AFP.
He said it was only after checking the camera data that they realised the eagles were under “severe food stress”.
Feed starving eaglets
The researchers estimate that deforestation means that around 35 percent of northern Mato Grosso is now unsuitable for breeding harpy eagles.
The long-term survival of the harpy eagles depends on forest conservation, and Miranda said this would need forest fragments to be reconnected as well as “real action from the government to prevent illegal deforestation”.
In the short term, he said groups should give food to starving eaglets. “Nowadays, when we monitor individuals under food stress, we offer them supplementary food if required,” he said.
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