Most European Ospreys nest in the north and winter in Africa south of the Sahara (apart from a few Mediterranean populations which are more or less sedentary). A few birds stop before crossing the Mediterranean and winter in Spain or even in the south-west of France, but this is unusual. In Switzerland Osprey migration occurs over a fairly wide period, and small numbers of birds can be seen mainly from mid-March to the end of May in the spring and from mid-August to the end of October in the autumn. Continue reading Migration
The reason that it is very unlikely (with nature you can never say impossible, but we can say very unlikely) that the Osprey will start breeding in western Switzerland again without help is due to “philopatry”. Philopatry is the tendency of an individual to stay or to return to the place where they were born in order to breed. Some species, like the Osprey, have a very strong philopatry, which results in a very limited ability to disperse to new areas. This means that when a population disappears, it is exceedingly unlikely that individuals who were not born in this area will recolonise it, even if suitable habitat exists. 
