Today’s series of pictures was sent by Lou Jost, a biologist living in Ecuador, but the photos were taken by his colleagues. It’s a sad tale, but it’d natural selection, Jake, and the photos are superb.
Lou’s notes:
These aren’t my pictures, they are pictures taken by people I invited to photograph our baby eagle…so perhaps it is still sort of “Readers’ Wildlife” photos?
Back in May one of our reserve caretakers, Fausto Recalde, discovered a nest of the endangered Black-and-chestnut Eagle (Spizaetus isidori), a giant eagle capable of carrying off monkeys. This was one of only a handful of nests ever found of this species, which lives in a narrow band along the middle slopes of the northern Andes. (Jerry has previously posted my video of a fledged juvenile in our Cerro Candelaria Reserve.)
The nest was in its very early stages, either incubation or recently hatched (the guards couldn’t see a chick), so we could watch the whole process unfold. Our guards took some photos but were limited by their equipment. Then Mark Wilson, a naturalist working on a book about the giant eagles of the world, heard about this nest and one other nest in Ecuador. He didn’t have good material on this eagle, so he rushed down to photograph the nests for his book. With his permission, here are some of his shots from the two nests. [JAC: captions are below the photographs.]
Mark and our guards found that the eagles fed their chick not on monkeys or squirrels or other mammals, as I had expected, but almost exclusively on guans (Chamaepetes, and probably also Aburria and Penelope), which are large turkey-like birds of the forest canopy and midstory.
Shortly after Mark left, our bird started tentatively to explore the branches of the nest tree, as seen in these photos taken by our guard Santiago Recalde. It also became more assertive, and the adults now kept a respectful distance while it fed. I suppose in eagle years it was now the equivalent of a rebellious human teenager.
When the guards returned to the nest a week after taking these pictures, they were shocked to discover the baby’s cleaned-off skeleton laying in a pile of feathers at the foot of the nest tree. There were no obvious signs of foul play, though the head had been removed by some animal which broke the skull around the eye sockets. Ruth Muñiz Lopez, an Ecuadorian expert on large eagles, told us that young eagles frequently get into trouble like this on their first flight, losing altitude and then getting trapped beneath the canopy and unable to return to the nest.
Natural Selection in action. Sad, but hopefully their next chick will be a bit more cautious in its first excursions from the nest.
A regretful result! But as has been said that is the way of nature. I see the skull and the upper beak.
Yes, very sad for the chick, but nature is brutal. Still, I’m glad for the post. I’m not familiar with that species and they are beautiful birds, especially the females.
Actually the male and female are identical in color (though females are larger). The white one is the juvenile. The juvenile keeps that plumage for at least a year.
Oh, I see. Thanks for explaining.
Taking your first flight by jumping out of a high nest does sound a lot more dangerous than starting from the ground, but I suppose transferring the chick to the ground or nesting nearer the ground would be even more dangerous.
Is this “jump followed by fly/plummet” the usual method of learning to fly for most bird species?
Trigger warning…just kidding. But that is sad that the eaglet didn’t make it. What a beautiful eagle, and one I’ve never heard of. Mark Wilson obviously captured some great moments, so at least the eaglet will live in the pages of his upcoming book.
Yes, Mark did a great job, and if his pictures of other eagles are as good as these, it will be a very good book. Not many people know this eagle, since its range is quite small.