Osprey migration: facts and map

Ospreys are found all around the world. A few populations stay in the same areas all year, but most have a winter home in the south and a summer home in the north where they breed. The journey is tough and dangerous. But evolution would not tolerate such risky behaviour unless there was a considerable upside. Here’s everything you need to know about osprey migration.

Where do ospreys migrate?

Although a few are now seen in Spain and Portugal, most British ospreys overwinter in West African countries like Senegal and The Gambia. They have quite an easy time of it there, in a pleasant climate with plenty of fish to eat. 

Why do ospreys migrate?

Why don’t ospreys just nest in the south and skip the arduous 6,000km journey north? The main reason for migrating north is the long hours of daylight enjoyed there during summer. While nesting, the father hunts fish by sight to feed the whole family - longer daylight hours means more opportunity to catch enough food to go round.

Fewer predators will threaten eggs and flightless chicks in the north too. Scotland does not have cobras like Senegal!

Ospreys usually build their nests close to water for better access to the fish they eat, so another advantage for ospreys travelling to our Loch Arkaig Pine Forest in Scotland is a seasonal abundance of catchable trout in the loch. Insects such as mayflies, caddis flies, stoneflies and all sorts of midges, gnats and smuts live as larvae in the depth of the loch. In summer these rise to the surface, emerging into the air as adult flies ready to breed. Trout follow the insects towards the water’s surface, moving within range of diving ospreys which can only catch fish in the top metre or so of the loch.

The birds return to the south for the same reason - any osprey that stayed north would be unlikely to find enough fish to survive. As well as short winter days reducing available hunting time, the insect larvae move deeper in the loch, taking the trout with them – and the water may freeze over altogether.

What months do ospreys migrate?

It all depends on the weather, but generally ospreys arrive in the UK in late March to early April. They tend to head south again around September. The journey can take 4-6 weeks.

Do ospreys migrate together?

Ospreys often return to the same mate, but they migrate alone. At the end of each nesting season, the family bond breaks as each member of the osprey family departs one by one over a period of weeks.

The mother is first to leave, then the chicks set off one at a time and father leaves last. The birds will have no association with each other until the adults hopefully reunite at the nest to breed again the following year.

Climate change risk to osprey survival

Climate change threatens this specialised lifestyle and its delicate relationships.

An osprey in West Africa contemplating a 45-day flight all the way to Scotland is relying on the behaviour of tiny midge larvae deep in Loch Arkaig to make it all worthwhile. But if warmer winter spells encourage insects to hatch earlier, there will be less of a bonanza in summer when osprey fathers need to bring fish to their new families.

More migrating birds could also perish if the weather gets rougher on their route.

Osprey migration at Loch Arkaig

Each year, after a successful breeding season, the ospreys we follow at Loch Arkaig Pine Forest begin their journey south.

Although resident pair Louis and Aila had been delighting viewers of our nest camera, supported by players of People’s Postcode Lottery, since 2017, only Louis returned in 2021. He paired up with a new female, Dorcha, at another tree in the forest, raising two chicks (Aspen and Alder) away from our camera. Once the birds had left for the year, we installed another camera at this new nest site, and captured Louis and Dorcha's second brood growing up in 2022. The rest, as they say, is history!