There is exciting news from a little further south in the UK at Rutland Water of the first osprey arrivals for the 2014 breeding season! Here we have put the finishing touches on the new camera and new microphone on our nest and are keeping a very keen eye out from the hides in all daylight hours for birds arriving from spring migration . As we await the arrival of the birds, we thought we’d review some of the most commonly asked questions about migration- remember there are lots more like this under the FAQ tab at the top of this page too.
Why do ospreys migrate or indeed any bird?
Migration is still one of the mysteries of nature – scientists and nature lovers are still discovering the why, where and how for many species, and technology such as satellite tracking is revolutionising our understanding.
Basically, migration just means moving with the seasons and birds migrate for several reasons: To avoid bad weather (e.g. frozen Scottish lochs in winter for a fishing osprey) , to make use of better food availability (e.g. geese going to Arctic to eat the summer grass glut or swallows following insects) or avoid predators or find safer nesting areas. One crucial factor is daylight length: here in Scotland we have nearly 22 hours of daylight in summer breeding season which means a lot more time to fish and support a family. If an osprey stayed in West Africa to breed, it would have only the same 12 hours of daylight all year and more predators to deal with too.
It is thought that long distance migration has evolved over millennia, by gradual ‘stretching’ of more local seasonal movements as climate changes.
How do ospreys migrate?
We know most UK ospreys travel south via a route that takes them over England, (though some go west over Ireland) and then usually over western France, then Spain or Portugal. They often cross near Gibraltar, then hug the African coast to their eventual destination, as too far inland means crossing desert.
We know most ospreys take between 4-6 weeks to make the journey in autumn, but are considerably faster on the way up in spring (the breeding instinct is strong and they must get to the nest first!).
Young birds make more stops and wander more before settling down to habitual yearly pattern. Most birds go to the same over-wintering area each year routinely – creatures of habit! They stop many times on route and can spend up to a week or more on a particularly good estuary or river, especially if weather is unfavourable.
They can fly at considerable heights, at up to 100km a day and can even fly up to 48hrs non-stop!
Most miraculously of all, we still do not know exactly how they navigate – probably some combination of visual clues (we know they fly more in good clear weather) and certainly genetic instinct, and probably some form of geomagnetic perception we do not yet understand.
Which countries do ospreys go to when they migrate for the winter?
UK Ospreys go to West Africa, to countries like: Ghana; Sierra Leone; Ivory Coast; Senegal; Nigeria; The Gambia; Mauritania; Guinea; Guinea Bissau ;Cape Verde Islands; Togo; Benin; Niger; Cameroon; and Liberia.
Do you know where “Lady” migrates to?
Our resident female has left on her migration as the breeding season and her responsibilities are now over. We do not know exactly where she migrates to as she has never been ringed, tagged or tracked, and is not a suitable candidate due to her age. By studying the migration routes of her offspring, we hope to gain some insight into her habitats as it is believed ospreys inherit the latitude of their wintering grounds from their parents.
Do chicks leave on migration before or after their parents?
Most often the female leaves first, then the male and the chick last when necessity calls! Sometimes though the male hangs around for a day or two after the youngster leaves, then heads off himself- each bird is an individual.
Do the youngsters migrate to the same area as their parents?
Yes, we believe so – It is thought that young osprey chicks follow inherited genetic programming which tells them where to head on their first migration.
Migration is a very dangerous undertaking for young ospreys – in the wild, between 40-70% of all young birds die in their first year. Once they have arrived in Africa, the young ospreys don’t return for the first three or so summers. However, once their hormones kick in and they are old enough to breed, they begin their return journey.
Do ospreys join up in any kind of group to migrate , or are they pretty much on their own, or is it a little of both?
No, the parents and their chicks do not travel together or meet up. We know this because ospreys are very rarely seen on migration in the company of others and almost always leave for their journeys at staggered times. Only once they reach Africa, can they sometimes be seen in high densities on estuaries and coastal areas, but each keeps their own space and they don’t ‘flock’ like many other birds, or use large communal roosts.
Do the male and female meet up down south, or only when they come back to the nest each year?
We don’t believe so – ospreys have never been recorded in Africa with their nesting partners. This is the same with many migratory birds, even those that mate for life. However, with the new research coming in from satellite tracking, we may learn more about where mated pairs spend their winters.
Why do ospreys come to Scotland when the weather is so changeable here?
Ospreys breed in Scotland for several reasons:
We have lots of clean healthy rivers and good fish stocks- lots of food
We have good nesting sites in large trees in quiet places (not too many people about)
We have relatively few predators (well we have Pine Martens and man, but no monkeys, tree snakes and crocodiles like in Africa)
We crucially have long summer daylight- up to 22 hrs a day in midsummer when the chicks are hungriest which is a great advantage to a bird which needs good light to find its food.
Although our weather is changeable it isn’t too extreme, hot or cold- ideal for raising a family.