Osprey Fact File
The osprey has chocolate brown feathers on its upper side and white feathers on the underside. These white feathers are an adaptation which makes them harder to see for both prey and predators while they are flying. A dark line runs back from the eye.
On the back of their head is a ruff of feathers which may be raised to make them look larger when they are angry.
They have a slightly hooked black beak and yellow eyes. Their feet are off-white. These feature two toes in front and two at the back which provide a strong, flexible grip that helps them to catch and hold fish which may weigh more than they do.
Females and males have a few slight differences which help in telling them apart. These include the male being slimmer and having narrower wings.
Their body measures 54-64cm (21.5-25in) long while an average weight is between 1.5 and 2kg (3.25-4.5lbs). Their wingspan is 1.5-1.7m (4.9-5.6ft) across. Females are slightly larger than males.
They have a range of adaptations to help them catch fish and it is only when this food source is scarce that the others are eaten. Fish are carried head-first.
Wild 8-9 years
Ospreys are among the world’s most widespread birds and can be found on every continent except for Antarctica. The population in Australia is now considered to be a separate species known at the eastern osprey.
They make their home near water. This can either be fresh or saltwater as long as there is enough area to support medium sized fish. This includes rivers, estuaries and along the coastline. They are not found far out to see unless on an islet or exposed reef.
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The breeding season is variable across their range.
They build a large nest known as an aerie. This is reused by the pair each season which means they can grow to be extremely large. Nests are built in trees or where they live near humans these birds may nest on a man-made structure such as a pole, tower, building or artificial nest platform.
This nest is formed from sticks. It may then be lined with twigs, grass, bark, fish bones and moss along with stranger items such as plastic bottles.
Females will deposit between 1 and 4 eggs in to the nest which are then incubated for 44-59 days. 1 brood is produced each year. Incubation is shared by both parents with the male going out to find food and bringing this back for the female.
As the chicks hatch it is staggered so each emerges from its egg a few days apart from the others. This means the first hatchling is dominant and if food becomes scarce it will outcompete its sibling for food.
Young fledge between 44 and 59 days old. After fledging they will spend 2-3 months learning how to hunt from their parents.
They will breed for the first time at 3 years old.
To catch fish they will perform a feet-first dive in to the water. When they enter the water they can close their nostrils to ensure water does not enter it. They also have a nictitating membrane (third eyelid) which covers the eye when they enter the water. This is semi-transparent meaning they can see while the eye is protected.
Each year the osprey which live in the north of their range will move south for the winter.
They are mostly quiet but near their nest they will make some vocalizations.
Predators and Threats
During the 1950s the population of ospreys decreased due to the chemical DDT getting in to the ecosystem and leading to thin egg shells.
Further human threats include deforestation and the removal of eggs from their nest. They may also abandon their nest if disturbed by humans.
Currently the main threat is shooting.
They are also known as the ‘fish hawk,’ ‘sea hawk’ and ‘fish eagle.’
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