One of the highlights of working on a nature reserve in spring is watching the daily changes as it bursts into life after the stillness of a tedious, long winter. I always look forward to helping our staff and volunteer team with our bittern surveys, where we sit and watch out for bittern feeding flights. At times the bitterns can be a little secretive, and I can become distracted.

Often on these occasions I find myself listening to the cuckoos, a well-known spring visitor, who has kept me, entertained with their unmistakeable song or the female’s bubbling call as the male chases her across the reed bed. It is such fun to watch their antics.

Since the early 1980s cuckoo numbers have declined drastically and this recent population decline makes the cuckoo a red list species. One of the reasons for the decline is that there are fewer host bird’s nests available for the cuckoo to lay her eggs. Another reason is the deterioration of conditions of their migration routes to Africa. However, here at Lakenheath Fen nature reserve, giving nature a home means it is usual to hear and see cuckoos throughout spring and summer. Cuckoos arrive from sunny Africa in mid-April and after breeding the adults head back in July or early August. The young cuckoos follow in late August to early September. It reminds me of my Nan’s old saying:

The cuckoo comes in April

She sings her song in May

She changes her tune in the month of June

And July she flies away.

Cuckoos are well known brood parasites where the female will lay her eggs in the nest of a small insect-eating bird. One of their regular “host species” is the reed warbler, which is doing well here at Lakenheath Fen. In some years we have had around 800 nesting pairs. Other host birds are dunnocks and meadow pipits. A cuckoo egg will closely mimic the eggs of the host; the host may abandon the nest if they recognise the foreign egg. When the young cuckoos hatch, which is usually just before the others eggs hatch, they eject the host’s eggs and any young from the nest. Foster parents are fooled into believing it is their chick despite the huge size of the cuckoo, and will incubate and feed the young cuckoo for several weeks with a diet of hairy caterpillars, eggs, worms, grasshoppers and other insects.

We usually have about five or six cuckoos that turn up in mid-April around the reserve. Many of our visitors are very impressed to see and hear our cuckoos as they struggle to find places where they can still hear them. A couple of years ago, our visitors took some very entertaining photographs of a host wren bird bringing up a very chubby cuckoo. The tiny wren looked totally worn out.

Lots of poets and writers have written beautiful prose after being inspired by the timeless call of the cuckoo.

For me, it brings to mind the beautiful hot sunny days of my youth and a typically British summer afternoon. Come and meet them yourself at Lakenheath Fen nature reserve.