Outdoors: The annual migration of swallows is one of nature's great events

Only a few weeks previously these very same birds had been in northern Europe, possibly even Scotland, yet instead of the cows and sheep of a Scottish pasture for companions, they were now hawking for insects against a very different backdrop of elephants and antelopes.

It is a truly gargantuan migration for such a delicate bird and one that our Scottish swallows will embark upon in the next few weeks. As summer draws to a close swallows begin to congregate in groups of varying sizes, often gathering together on telephone lines or in reed beds, and then at the behest of some unknown cue, they strike southwards.

The journey is a dangerous one and some will perish over the vast parched expanses of the Sahara and Sahel before encountering the lush forests of Zaire and then the bushlands of Angola. And although many will end their journey on the insect rich marshes of the Okavango, others will continue on south to final wintering grounds in South Africa.

But as the first of our swallows depart, others are engaged in a race against time as they still have young in their nests, either because they were late starters or because they decided to squeeze out just one more brood. It is not uncommon for swallows in Scotland to still have young in the nest at the end of September, despite the fact that most of their compatriots are probably by this stage many hundreds of miles away. As soon as the young leave the nest, then they too must head quickly south.

The endurance displayed by the swallow during their great migration is remarkable, as is the unerring navigational ability, which is underlined by the strong fidelity to the natal site, with birds often returning each spring to the same barn or shed they nested in the previous year.

The swallow is undoubtedly one of our more attractive birds but its dashing nature usually makes it difficult to fully appreciate the fine iridescent blue-sheen plumage with deep chestnut throat patch and long tail streamers. Swallows feed mainly on winged insects such as horseflies and blue bottles, but they will also sweep small creatures off grass or the surface of water.

Swallows have been associated with people since Neolithic times because of their preference to build their nests of dried mud pellets near human habitation in old buildings or beneath bridges, rather than natural but scarcer sites such as cliffs and caves. They are also attracted by the open spaces created by farming, especially pasture land which is rich in airborne insects. This inextricable link has led to the birds becoming deeply entwined in folklore - for example to destroy a swallow's nest or kill a bird was widely believed to bring bad luck.

It also led to much head scratching as to where the birds went in winter. Gilbert White, the eminent 18th century naturalist, whilst believing that some swallows may migrate, was not alone in his belief that many also hibernated in "holes and caverns and do, insect-like and bat-like, come forth at mild times".

Given our scant knowledge of wildlife at the time, such a conclusion seems an entirely reasonable one to make and would certainly seem much more plausible than had he hypothesised that the dainty swallow migrated 6,000 miles to the furthest end of Africa - a journey that would have taken an 18th century sailing ship many weeks to complete.

This article was first published in The Scotsman on Saturday, 4 September, 2010