ChicksA young Osprey spends the first seven or eight weeks of its life confined within the nest (or eyrie), a huge pile of sticks lined with moss, bark and grass. It will probably have two siblings which may be very different in size and is fed by its mother which stays in close attendance, tearing into small pieces the fish provided by her mate. By the age of two weeks the youngsters are able to move around the nest and at a month they are very active, preening and exercising their wings. Gradually the wing-flapping increases until they are able to lift a little off the nest and then take their hesitant first flight. |
These young Ospreys are about five weeks old and have been brought down from their nest to be ringed. Notice the pale fringes to the dark feathers - the adults' feathers are darker with no fringes. |
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Fishing
Ospreys look for fish by hovering over the water, although sometimes they are able to use a perch from which to sight their prey. They dive into the water with wings swept back, thrusting their talons forward at the last minute to grab the fish below the surface. Adults are successful about once every four dives, but it takes the inexperienced juveniles many more attempts before thay are successful. Ospreys hunt for fish in both salt and fresh water.
First migration
By late August or early September, the young Ospreys leave their nest sites and head southwards. Many of the Scottish birds have been ringed before they leave their nests and this has provided much information about their movements. Sometimes the ring numbers have been read in the field and sometimes rings have been taken from the bodies of dead birds. Young Scottish Ospreys have been identified in this way in the south of England and Wales, Brittany, Spain and Portugal, North Africa and as far south as Senegal and Guinea in West Africa. It is this area where the Scottish birds seem to spend the winter, arriving there in October and fishing along the coast and in the mangrove swamps.
Please see the Satellite Tracking part of this website to see maps and details of migration of some Scottish and Rutland Ospreys.
Returning to breedExperienced adult birds leave West Africa and head north to the breeding areas again in March. However, younger birds do not reappear at the sites from which they fledge for several years. Sometimes they return when they are 2 years old, but those that survive do not begin to breed until they are aged 3 to 5 years. Occasionally a pair will build a nest and establish a territory one year, only returning to breed the following year. It certainly seems to be the case that Ospreys, especially the males, return to breed in the vicinity from which they themselves fledge. This explains the relatively slow expansion of range in Scotland and is why translocation of young birds before they fledge has proved successful in establishing new breeding populations. |
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Nest sitesOspreys generally mate for life and the older, experienced birds usually arrive back in the nesting area first with established pairs nearly always returning to their previous nest sites. New pairs must find new sites when thay arrive and often have difficulty finding a suitable natural site to hold the nest, which will often be over a metre wide. They usually choose a site within 3-5 kilometres of water and prefer to have an open area around the future nest so as to have easy access when landing. Flat-topped trees are the most likely natural site but Ospreys take readily to man-made structures such as power pylons and radio towers. In many parts of their range Ospreys have used artificial nests especially if built over water. There are several such platforms now in place at Rutland Water, in the hope that these will prove attractive for the young translocated birds when they return. |
An adult
Osprey on its eyrie in the top of a Scots Pine
tree in Scotland.
Photo: Tim Appleton 
An artificial nest site and perch, sited in the
south arm of Rutland Water reservoir.Attracting a mate
Within the UK , the display flight of the male Osprey has probably been observed most frequently by Roy Dennis and in his book he describes it like this:
It is a most beautiful spectacle although often difficult for us to observe. After catching a fish, the male gains height as he returns to the nesting area and while still several kilometres away he starts his display. To me the display call is very distinctive; it's a high-pitched 'pee-pee-pee-pee...pee' and if I search the skies I will see him soaring majestically, maybe a thousand feet above, as he moves in sweeping circles closer and closer to the nesting site. He climbs several hundred feet upwards with rapidly beating wings, then hovering briefly, with fanned tail, he performs a breathtaking dive showing the fish grasped in outstretched talons. He pulls out of the dive and powers sky-wards to repeat the performance. All the time his calling can be heard by his mate and finally his last stoop takes him in a long power dive right to the eyrie, where the fish is presented to his mate.
(Ospreys, by Roy Dennis, Colin Baxter Photography Ltd, 1991, p13)
Eggs and incubationIn Scotland female Ospreys begin to lay their eggs in late April. The eggs are beautifully blotched reddish-brown and are about the same size as a large hen's egg. They are produced at two-day intervals. Novice breeders will usually lay two eggs; more experienced birds lay three and, just occasionally four. Both adults will take part in the long incubation process but the female takes the major part with the male providing her with food and chasing away any potential predators. Click here to see an analysis of the incubation period of the Rutland Water nest in 2002. Until fledging the female stays on or close to the nest site but after the young have fledged she joins the male in bringing food back to the nest site. Ultimately the young become independent hunters and the adults' role as parents and providers is finished. |
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Life span
Some of the Ospreys in Scotland are more than 25 years old. We know this because when they are chicks small numbered rings are fitted on their legs. Then, years later the ring numbers can be read when they come back to build their nests and have chicks of their own.
On 15/3/2000 an Osprey with ring number M9976 was found electrocuted near Agadir in Morocco. It had been ringed as a chick in Scotland on 20/7/1974 so was over 25 years old - a new longevity record for Ospreys. (This information from the Ringers Bulletin, published by the British Trust for Ornithology.)
However, although some Ospreys live to a ripe old age, not all of them do. In fact, most of the young die before they reach 3 years of age and are old enough to breed themselves. The same is true for all types of birds. If all the young Blue-tits that leave the nest survived to breed themselves, the world would very soon be over-run with Blue Tits!