FOR most of us, an indication of the presence of a cuckoo is that unmistakable call which echoes the name of this distinctive summer visitor. For many superstitious country folk, even in fairly recent times, the sound of the cuckoo's first call of the year was the time to turn over the money in one's pocket or purse. This act was thought to bring good fortune, especially if the cuckoo's call was to one's right, with the most fortuitous time to first hear the cuckoo being on April 28. By turning your money on that date, you would gain prosperity for the whole year.

In very general terms, the cuckoo's first call of the year is usually heard around mid-April; April 14 is often known as Cuckoo Day because, by tradition, this is generally the date its voice is heard for the first time in any new year. As that date is also the feast day of St Tibertius, it led to an old saying that "the cuckoo sings from St Tiburtius to St John", St John's Day being Midsummer Day, June 24. Another old idea was that the first call of the cuckoo heralded the time to plant your seed potatoes - "When you hear the cuckoo shout, it's time to plant your taties out".

In truth, of course, we might hear the cuckoo at any time in spring and early summer - there is even record of a cuckoo arriving in the south of England as early as February in 1990 but they are seldom heard in this region during late July or August, the time this distinctive bird returns to Africa for the duration of our autumn and winter.

While many of us might already have heard the cuckoo, with others first hearing it during this month or later, the chances are that will be the only indication of its presence. Trying to locate a cuckoo from the sound of its voice is like chasing the end of the rainbow - you hear "cuckoo" in the distance, you head towards the sound, but the next time you hear the bird, the sound comes from a completely different direction - and you have not seen the bird in flight.

From these experiences, it is easy to accept that our forefathers believed the cuckoo was some kind of sprite or mystery bird and I am sure that, out of all those who hear the cuckoo, few actually set eyes upon it. Indeed, a high proportion of us would never recognise a cuckoo, perhaps thinking it was some kind of hawk or pigeon.

It is a large bird, over a foot in length (33cm), with slate grey plumage on its back, a dark-grey barrel white breast, with dark wing and tail tips. The wings are pointed and this makes the bird appear to be hawk-like during flight. The tip of its long tail is rounded and it has yellow legs. Young cuckoos are more brown than grey, and their wing tips are rather more rounded.

Sometimes, a cuckoo will burst from cover while hotly pursued by a flock of smaller birds. Like us, those brave little birds often mistake it for a bird of prey and gallantly chase it away from their haunts although, of course, they might well recognise the cuckoo for what it is.

In fact, the cuckoo is a most unpleasant character because it is a parasite which lays its eggs in the nest of other birds, thus forcing its young upon unsuspecting foster parents and destroying the eggs of the host bird.

The female begins her egg-laying during the latter weeks of this month. She tours a selected patch of countryside seeking the egg-filled nests of small birds such as meadow pipits, hedge sparrows and reed warblers. Once she has selected a nest, she removes one of the existing eggs and then lays one of her own in its place. These alien eggs can closely match the colouring of those already in the nest and a female cuckoo may lay as many as 12 eggs in 12 separate nests.

When the baby cuckoo hatches, it instinctively ejects the remaining eggs from the nest, hoisting them over the side. To do this, it manoeuvres itself beneath an egg so that it rolls into a hollow on its bare back and then, by using its featherless wings and legs, it hoists the egg over the side with an amazing display of dexterity. In this way, cuckoos destroy thousands of eggs which would otherwise hatch into small birds.

The unfortunate foster parents are then left with a baby cuckoo in the nest and this grows at an alarming pace, quickly becoming far larger than its foster parents who are now faced with the never-ending task of feeding this demanding parasite. These gallant little parents do not abandon their responsibilities - they feed the growing cuckoo until it is time to leave the nest. In August, the young cuckoo will head for Africa and then, next April, will return to this country to begin yet another breeding season which will kill many of our smaller birds.

From time to time, estimates of the scale of this destruction have been made but accurate figures are most difficult to assess. What is known, however, is that fewer cuckoos are now coming to this country; since the Second World War their numbers have dwindled quite dramatically. Perhaps we should not worry too much about that!

Updated: 13:27 Thursday, May 03, 2001