We are now into August and suddenly it feels like Forsinard has become quieter when it comes to birds. Most people recognise swallows congregating on telephone wires, or the “V”s of geese flying overhead as signs of the changing of the seasons, that they are “flying south for the winter”. But why do this? Why migrate? And where are the birds going?
Many species migrate, in that they travel from one area to another. Seasonal migrations occur when a species uses one habitat in one season and then travels to another for the next. For example, the swallow, spends the summer breeding in the UK and then travels back to Saharan Africa for the winter. Flying to Africa from Forsinard is a long way, so why travel that far?
Swallows Hirundo rustica and House Martins Delichon urbica - Nick Upton (rspb-images.com)
Migration is a form of adaptation. Adaptation in its simplest form is an adaption by the animal to survive in its habitat. Migration is a behavioural adaptation, a behaviour that aids survival. For some species it is to find food, to find suitable breeding habitat or to avoid bad weather, or possibly a combination of all 3.
Forsinard Flows is perfect for many breeding birds, it is a predominantly upland habitat mainly consisting of blanket bog. In the summer the pool systems and lochs are full of freshwater invertebrates as well as the huge number of flying insects, there is no shortage of midges here! So there is plenty to eat. Not only that but long hours of daylight mean that birds can be out catching insects for much longer periods of time. And as the bog is so vast and open breeding birds can see danger from long distances. The Flow Country is a perfect habitat for breeding and raising chicks and the species that come here to breed are widely dispersed across this remote and wild landscape. But in the winter it’s a different story. Temperatures drop, nights get longer, the bog freezes over and you will see no flying insects. So the Flow Country changes from being very suitable habitat to very unsuitable habitat quite quickly. This is where migration comes in. The birds will leave Forsinard and find a more suitable, less harsh environment at which to spend the winter. Species such as Dunlin, Greenshank, Golden Plover, Common Scoter and Red-throated divers arrive in March and April to breed in the remote pool systems and lochans of the flow country and are here for a very short time over the summer. Species such as Hen Harrier, Meadow Pipit and Skylark will stay into the autumn. But by the winter the only birds you are likely to see at Forsinard are the buzzards and the ravens.
Common Scoter female Melanitta nigra with ducklings- Andy Hay (rspb-images.com)
So where do they go? For some such as the greenshank or the golden plover they will travel further south in the UK or to wintering sites at the coast, where they can still find food. Others such as the black throated diver, the red throated diver and the common scoter will head back to sea. And some will undertake migrations over huge distances, the swallow and the wheater to Africa and the arctic tern which travels from the Antarctic to the Arctic.
Golden Plover Pluvialis apricaria- Chris Gomersall (rspb-images.com)
It is incredible to think that something as small as a swallow (weighing less than 20 grams) can fly from Forsinard to Sub Saharan Africa in only 6 weeks, covering 200 miles or more in one day! And then do the return trip the next spring! And that juvenile birds after fledging can do the same journey as adults, without ever doing the journey before! Migration is amazing.
If you want to learn more about migration then the RSPB website has much more information. But next time you drive through the Flow Country in winter, with all your woolly hats and scarves on, and wonder where the birds are, just think, they are happily feeding somewhere much warmer. Clever birds.
http://www.rspb.org.uk/youth/learn/migration/
http://www.rspb.org.uk/advice/expert/previous/migrating.aspx
Juvenile Swallow Hirundo rustica -Tom Marshall (rspb-images.com)