Ospreys are vulnerable to predation from aerial predators, such as owls and eagles. The speckled appearance of osprey chicks camouflages them in the nest and may be an adaptation to minimize predation.
Alarm calls are often given when a potential predator or disturbance such as a boat or human approaches the nest. These calls are usually accompanied by erect posturing and diving flight. Both parents expend considerable effort protecting the nest from intruders, including other ospreys and potential predators.
Canon 50D, EF70-300mm f/4-5.6 IS USM