Theories, suggestions, answers:
Steve Lumb, of Lincolnshire asked:
I have read, and been advised by wardens at Loch Garten that once the young birds are able to fly they leave the nest for increasing periods of time. I was told that some of this time is spent with the adult birds while the latter are fishing. Some adult birds are known to drop fish caught so that the young may learn to catch them. It was my understanding therefore that the time with the adult birds, after leaving the nest, was a crucial one in the continued development of the young birds. Young birds at Rutland Water have no such 'instruction' when they leave the artificial nests - is my current understanding therefore incorrect and the young birds will learn to fish successfully regardless?
This answer was compiled by members of the project team:
In 1954 a British naturalist called Colonel Meinertzhagen published a paper in which he described his observations while on holiday in Sweden. The paper, entitled The education of young Ospreys, describes parents apparently luring young from the nest by flying past with fish and also repeatedly dropping fish into the water, perhaps encouraging their young to stoop for them. However, others have questioned Meinertzhagen's interpretation of his observations and it is difficult to find other evidence to support the "education" thesis. Roy Dennis believes that there is no evidence at all of Scottish Ospreys teaching their young to catch fish. It would certainly be interesting to hear of any recent observations of activity like this.
In the 1980s, experiments were carried out in the US which appeared to show that hand-reared Ospreys were able to hunt successfully within three weeks of fledging, even though they had no parents. The successful translocation project in Minnesota was based on this finding and confirmed it, as has our recent experience at Rutland Water. We have observed recently-fledged birds learning to catch fish, first by trailing their talons through water and then by watching for fish carefully from a perch over the water. On another occasion several of our young birds repeatedly swooped low over a recently-cut hay field, grabbing clumps of hay. Were they practising their catching skills or just playing? Certainly young at Rutland Water, like those in Scotland, have occasionally been observed to catch fish but for most of the time before they migrate they also return to the nesting platforms supplementing their diet with food that we put out. Once they leave Rutland Water the birds must be able to fish successfully as shown by the growing number of subsequent sightings.
The success of the translocation project indicates that the Osprey's ability to hunt must be largely innate, although, of course, that does not rule out the possibility that parents also encourage their young to start fishing.
Very many thanks - as I suspected, the romantic notion of parents teaching young is often mistaken.
This email came from Cathy Grieve in Cornwall.
Last year I witnessed two Ospreys passing through Cornwall during migration during September. One was clearly an adult bird, the other a young bird and clearly a very inexperienced fisher. We are certain we witnessed this adult bird "teaching" the younger bird to fish. Local birders reported the adult dropping fish into the river for the younger bird to retrieve. In view of your info that younger birds do not generally leave with adults it will be interesting to see if the satellite tracking gives any further info as to whether the birds sometimes travel in family / co-operative groups.
Jack Sandover of Loughborough University sent an email asking:
Are normal, parent reared, chicks in the same position as the released birds in that they have to learn all about fishing and migration on their own?
If this is the case, are the released chicks at an advantage in that they can learn from the experience of eleven other chicks rather than just one or two siblings? Are they likely to stay together on migration?
Helen Dixon replied:
Yes, as we said in answer to an earlier question, it does seem that juvenile Ospreys that have been raised by their parents do still learn to catch fish on their own. They are also thought to migrate without the help of their parents.
And, yes, we certainly have observed the Rutland Water juveniles apparently copying each other's activities including fishing attempts before they leave here. So in a sense you may be right that they are at an advantage because they have so many other juveniles to learn from.
We don't think that the juveniles stay together as they migrate because in previous years they have apparently left here at different times. Just occasionally two or more birds have left on the same day . This is another of the questions satellite tracking may help to answer.
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