Basin Notes - June 2000

All Change!

All change! The Basin's winter visitors are gone (almost) and the summer visitors are coming - bird visitors, that is.

The pink footed geese and waders are heading back to their Arctic breeding grounds and the long distance fliers from Africa are heading this way. Some, like the sand martin, swallow and willow warbler are here already. Others like the whitethroat and swift are due any day now. Sedge warblers are here filling the air with their "scratchy" song. That such small birds can fly such vast distances at all is amazing, but that they can navigate so accurately is simply astounding.

So how do they do it? First they must eat voraciously and double their body weight so that they can cross the major barriers; the Sahara desert and the Mediterranean sea. The increase in weight is all fat. That much fat put on in a few weeks would kill any human who tried it, but birds must do so to fuel the journey ahead.

Next they must head off in the right direction. They can orient themselves by the patterns of the stars, the position of the sun, the magnetic field of the Earth, by sighting landmarks and, possibly, even smells. They will set off on a favourable wind and travel the hundreds of miles with only a few stops to eat and rest.

Many will not make it. Adverse weather, predators (including man), exhaustion and starvation all take their toll. Those that do will immediately set about finding a mate and building a nest. Time is precious - they must breed as soon as possible to take advantage of the available food and also to give themselves the chance of a second or even third brood before the shortening days call them to the south and Africa.

While migration has proved to be a good survival strategy, many more bird species remain in the warmer climes near the equator and do not feel the urge to take part in these phenomenal journeys. So are the migrant species at a disadvantage? Despite the losses of individuals due to the rigours of the migration flight, the limiting factor for survival of the species as a whole is the quality of the feeding and breeding areas. If anything reduces the quantity of food or reduces the number of possible nest or roost sites at either end of the migration path then the species numbers will suffer. So the migrant species might actually have an advantage over the sedentary species as they may be more adaptable and capable of exploiting new feeding and breeding areas should the traditional sites become untenable.

We must make sure that the tired and hungry arrivals from the equator are guaranteed food and places to rest and breed. The Montrose Basin Local Nature Reserve is one such place. It is everyone's hands to make sure there are others.