Ospreys are superb fishers and indeed eat little else—fish make up some 99 percent of their diet. Because of this appetite, these birds can be found near ponds, rivers, lakes, and coastal waterways around the world. Ospreys hunt by diving to the water’s surface from some 30 to 100 feet (9 to 30 meters) up. They have gripping pads on their feet to help them pluck fish from the water with their curved claws and carry them for great distances. In flight, ospreys will orient the fish headfirst to ease wind resistance.

Ospreys are sometimes confused with bald eagles, but can be identified by their white underparts. Their white heads also have a distinctive black eyestripe that goes down the side of their faces. Eagles and ospreys frequent similar habitats and sometimes battle for food. Eagles often force osprey to drop fish that they have caught and steal them in midair.

Human habitat is sometimes an aid to the osprey. The birds happily build large stick-and-sod nests on telephone poles, channel markers, and other such locations. Artificial nesting platforms are common in areas where preservationists are working to reestablish the birds. North American osprey populations became endangered in the 1950s due to chemical pollutants such as DDT, which thinned their eggshells and hampered reproduction. Ospreys have rebounded significantly in recent decades, though they remain scarce in some locales.

Most ospreys are migratory birds that breed in the north and migrate south for the winter. They lay eggs (typically three), which both parents help to incubate. Osprey eggs don’t hatch all at once, but are staggered in time so that some siblings are older and more dominant. When food is scarce these stronger birds may take it all and leave their siblings to starve.

Q and A

Why do ospreys only live here for half the year? And where are they for the other half?

In Britain ospreys are migratory, which means that they travel to another part of the world as part of their life cycle. They spend their winters on the west coast of Africa, in Gambia and Senegal. They come to Scotland, and now to parts of England too, to breed.

So are all ospreys like this?

No. In Australia and parts of America ospreys do not migrate.

Why do ospreys bother coming here in the summer?

This is where ospreys are from. They are born here and they breed here. If it weren’t for traditionally harsh winters in this country ospreys would not have to migrate to warmer climates. The only reason that ospreys migrate in winter is because of the colder climate causing fish to stay closer to the bottom of lochs.

When they come here for the summer to breed, do they go to the same nest every year?

Most ospreys certainly use the same nest every year. Here at Loch of the Lowes our female has been coming back to the same nest since 1991, and our male has been coming since 2010.

Do ospreys pair up for life?

They tend to pair up for life, but if something happens to one bird then its partner is usually able to find a new mate.

How high do they fly?

They certainly fly a long way, and some are known to migrate over the Pyrenees, which have an average height of over 1,600m (5,250 feet).

What do ospreys eat?

Ospreys are known only to eat fish. Most ospreys, especially those in Britain, tend to live inland and therefore will have a diet consisting mostly of freshwater fish, although some individuals such as those in the Spey Bay area will feed on saltwater fish.

How big is an osprey’s nest?

The average size for an osprey nest is around 104cm (41inches) in diameter and weighs around 120kg (260lb)

How many eggs do they lay?

Ospreys tend to lay between 2 and 4 eggs.

How long do the eggs take to hatch?

Incubation takes between 5 and 6 weeks.

And do they all hatch at the same time?

No, the female lays each egg separately at intervals of around 2 days. She begins incubating each egg as soon as she lays them, which means that the eggs will eventually hatch in the same order that they hatched, and conventionally within the same time spaces.

How do you tell males and females apart?

Females are bigger than males, who have a slighter build and smaller stature. The markings on ospreys’ heads tend to be unique, and it is possible to recognise a bird if you watch them for a period of time.

How big do they get?

The osprey is regarded as a medium sized raptor, but even still it is large for such a category. Their length, from head to tail, can be from 52-60cm (20-24 inches) while their wingspan can be from 152-167cm (5-5 and a half feet). They can weight up to around 2 kilograms (just over 4lb).