We´ve been doing a lot of paper research on the harpy eagle, just to cover all our bases. We came up with one paper we just have to tell you about.
Barro Colorado Island was created about 100 years ago when the Panama Canal flooded the adjacent tropical rain forest. Since then, its become a protected area and heavily reaserched site.
Barro Colorado is small and most apex predators, including the harpy eagle, disappeared long ago. Small and mid-sized mammals thrive. That is why there were 65 troops averaging 19 howler monkeys each in 1999 when the experiment was run.
Two radio tagged harpy eagles were reintroduced into Barro Colorado. Now imagine you have lived life as a howler monkey lounging the idyllic canopy of Barro Colorado. Your mom and dad had a similar life. Their mom and dad – the same. You know what the principal cause of death for howler monkeys at Barro Colorado used to be? Disease. Yep, just like humans. No violent deaths in that howler monkey population.
Now, imagine one day two hobbit sized aerial predators with 5-inch talons specializing in ambush show up in the neighborhood. Well it turns out that was the experiment – reintroducing two radio tagged harpy eagles to Barro Colorado.
The result – harpy kills every 3-4 days, per individual. Again, think of this as your neighborhood.
Within a few months howler monkeys learned to give out alarm calls. These alarm calls were not used by howler monkeys just a few miles away, in the peninsula (no harpies there). Not only that, but whenever recorded alarm calls were played back from the GROUND, howlers immediately looked up. Basically, we learned the howler call for LOOK UP! And the learned it too 😊
As always – Giant Birds and Terrified Monkeys the link to the paper.
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