With Harriett’s help, the nest construction progressed rapidly. Harriett was pleased with the site. It was high in a tree top, safe from ground predators, had clear visibility and an abundant food supply swam just below. The nest looked like a bulky mass, five feet in diameter and six inches thick, but the tightly woven branches and sticks made it home.
Ospreys have few natural enemies. Mostly the eggs and the young are victims of predation, but sometimes, even adults especially incubating females are snatched from their nests by owls, under the cover of darkness. Eagles are another avian threat to osprey. Osprey and Eagles do not get along.
Even though ospreys, especially the males, fiercely defend their nests, a determined raccoon, fox, skunk or similar land predator might raid the nest to steal eggs or chicks. Ospreys tend to avoid these perils by building their nests on isolated spots such as islands, secluded trees, or on top of man-made structures such as nesting platforms, electricity poles and other, similar, hard to reach spots.
The male osprey is a formidable predator, himself. He is a very large raptor, a bird of prey, with an average body length of two feet and a wingspan of over six feet. His sharp hooked, cycle shaped, beak easily tears flesh from his adversaries, not to mention razor sharp talons with death grip strength.
Before the presence of industrial humankind, Ospreys were widespread and abundant. However, the presence of guns, chain saws, toxic chemicals, synthetic fish nets and other modern products have brought harm to the osprey’s environment. All-in-all, however, ospreys have survived recent ecosystem changes fairly well.
Being fish eaters, they were one of the many species that were affected by the use of the pesticide DDT. Egg shells of the osprey became thin and weak, and reproduction was essentially extinguished. A ban on the use of this chemical in the United States led to a resurgence in osprey populations. Although the threat is gone in the U.S. and Canada, DDT is still used in other developing countries like Venezuela, and residues continue to be present in osprey tissues today.
Other threats include power lines, gunshots, and other forms of poisoning. Polluted lakes, rivers, and streams, and the loss of forested habitat along major waterways are additional threats.
Eagles worldwide are the main competitors of ospreys for the ecological niche of an aerial, diurnal, fish-eating, raptor. Different eagles compete with ospreys in different parts of the world. These eagles often rob ospreys of their catch and might also drive them off good foraging and nesting areas, or kill their young. Ospreys are also vulnerable to predation from other aerial predators, such as great horned owls. The speckled appearance of osprey chicks camouflages them in the nest and may be an adaptation to minimize predation by diurnal avian predators like the bald eagle. (Poole, 1989; Poole, et al., 2002)
This is a video. Click the arrow. If you did not realize the last post also contained a video, you missed a good one.
Raccoons, snakes and other climbing animals are the major predators of osprey eggs and nestlings. Selection by such terrestrial predators may explain why the majority of osprey nests are built over water. Crocodiles sometimes kill ospreys bathing and roosting near water during the winter season. Skunks also have an affinity for osprey eggs.
“I’d like to tell you the story of Reggie”, said Harriett. But, I worry it is “over the top”.
I am concerned it may be distasteful to some of The Doctor’s readers. If so, please give him some feedback, so I will know what is appropriate, and what is not on this website. Reggie and his disease was the most horrifying experience of my life, and I feel I should share it with someone.