Every week, Cumbria Wildlife Trust update us on the sights and sounds that you may be encountering in our region as we enter a new season. In spring there is much to take in as we enter a time of renewal and new life in nature.

Luckily, this week we have Cumbria Wildlife Trust expert Chris Scaife on the case to let us into the secrets of the wildlife around us as we take in the delights of the warmer weather and longer, light evenings.

In today's piece, Chris updates us on a sound that will be instantly familiar to us all but, perhaps, is not as recognised as you might think.

There is surely no other bird whose call is so instantly familiar, and so entwined with the season, as the cuckoo. The sound of the male bird calling its own name is a welcome traditional herald of spring not only in Cumbria, but across much of the northern hemisphere.

This is certainly a bird that is more often heard than seen, as referenced in the opening lines of Cumberland’s own William Wordsworth’s poem To the Cuckoo:

“O blithe New-comer! I have heard,

I hear thee and rejoice.

O Cuckoo! shall I call thee Bird,

Or but a wandering Voice?”

Famously, cuckoos do not rear their own young. They are known as brood parasites, meaning that the adult female lays an egg in the nest of another bird – in Britain, usually a reed warbler, dunnock or meadow pipit.

The host birds will occasionally remove the cuckoo egg from the nest, or abandon their clutch altogether, but more often than not they will incubate the new egg and rear the chick that hatches out, even as the young cuckoo grows to a size far greater than that of the adult host bird.

The sight of a 12g reed warbler placing a caterpillar into the gaping mouth of a 100g cuckoo is nothing short of a natural wonder.

Cuckoos spend only a few months in Britain each year; most of their time is spent in sub-Saharan Africa. In fact, most of the cuckoos that breed in Britain share their wintering grounds with leopards, elephants, lions, chimpanzees and gorillas in the rainforests of the Congo.

Like those African species, the cuckoo’s population is in steep decline. There are likely to be several reasons for this.

Climate change has an impact. With warmer weather earlier in the year, host birds tend to start laying eggs earlier now than they did in the past, but cuckoos are not returning to the UK any earlier. As a result, by the time they arrive it is often too late to find a host nest.

Cuckoos rely on insects, their diet mostly comprising moth caterpillars, and it is well known that insect numbers are not what they used to be. There is also general habitat loss in the UK, the Congo and across their migration route. Conservation and an increase in wild areas are needed if this iconic bird is to continue to be our herald of spring.

Cumbria Wildlife Trust is the only voluntary organisation devoted solely to the conservation of the wildlife and wildplaces of Cumbria. The Trust stands up for wildlife, creates wildlife havens, and seeks to raise environmental awareness.

Formed in 1962 and supported by thousands of members and supporters, the Trust cares for 38 nature reserves, across the country.