Question: Other than Bald Eagles, toward what birds are nesting Ospreys aggressive?
Answer: In over 20 years of Osprey nest censusing, the only bird other than Bald Eagles that we have observed being harassed by Ospreys is Brown Pelicans.
The pelicans have to be on the water near the active nest. Ospreys will not go after them if they are flying near the nest. This has been observed numerous times.
Why do Ospreys feel threatened by this large bird on the water in the vicinity of the nest?
One theory is that pelicans on the water appear to be ground predators getting ready to climb into the nest. Are there any other ideas?