The Osprey that we have seen lots of over the summer has decided to head to its winter home. This is in West Africa and we marvel at how these birds find their way back from Scotland. There have been lots of studies done with birds being tracked through Europe, the route usually takes them through England, western France and then Spain or Portugal. They often cross to North Africa at Gibraltar and then hug the coast line to avoid flying over a desert . The same birds will follow the same route every year which makes sense as they will know the way and where they can rest and feed on the journey. So why do they leave Scotland in the winter? Well its not so that they can sit and enjoy the warm sunny African climate (although that must be something to do with it) it is to do with their main diet; fish! Ospreys eat almost nothing but fish but they can only catch fish which are really near the surface as they are not built for swimming. This is fine in Scotland in the summer when trout and other fish are near the surface but in the winter a lot of Scotland’s lochs will freeze over and in coastal waters the fish will be much deeper and therefore inaccessible to Ospreys.
Adults will return to Scotland in March to breed but this year’s young will not come back to Scotland until they are ready to breed, usually after three years. But why do they risk this hazardous journey to breed when it would seem sensible to stay in Africa?
Well, there are several reasons;
- We have lots of lovely rivers with good fish stocks (when they are not frozen!)
- There are some great nesting sites in large trees in quiet areas
- In Scotland there are relatively few predators to attack ospreys or their nests. (probably only pine martins could reach and take an egg). In Africa there are monkeys and snakes to attack the nests and crocodiles to attack osprey as they fish.
- Crucially Scotland has long daylight hours in the summer which is critical as the adults need good light to find lots of food for a hungry chick.
Although the Ospreys have gone we are really lucky to have so many birds of prey that stay all year round including the Sea and Golden Eagles giving us great sightings all through the winter.