The evening sunlight dappled the pools at, yep you guessed it Cranwich J The resplendent greens, browns and gold of the bushes and trees shone in the golden, evening light, their reflections shimmering in the calm, clear waters. After a day at work we headed to the reed bed in order to check some of the reed warbler nests and ring any broods that were old enough. Calculating the age of nestlings is important for ringing the chicks, too young and the ring will slip off the foot, too old and they are liable to go for walkies! One nest today had an extra special inhabitant… a cuckoo chick!
The cuckoo, a summer visitor and a brood parasite; rather than going through the effort building a nest, brooding eggs and feeding ravenous chicks, the cuckoo lays its egg in the nest of another birds. Species high on the ‘hit list’ for cuckoo’s are meadow pipits, dunnocks and reed warblers. Once a nest is selected, the female swoops in, eats one of the existing eggs and lays her own; the whole process takes less than 10 seconds! Once the egg is laid, the female leaves never to see its offspring again. On hatching the blind, naked chick proceeds in removing the other eggs, scooping them up on its back and shimmying the egg up and out, until it is the only remaining occupant. From this point on it dupes the adult birds into feeding and raising it as their own, amazingly the chick’s call mimics that of a full brood of chicks, so that it gets four times the amount of food. Brutal, but clever!
|A cuckoo egg laid in a reed warbler nest|
This amazing bird, like so many, is in decline and is now listed on the Red List of British Birds of Concern. The reasons for these declines are complex and numerous, with many studies now looking at each stage of the life cycle. We have all heard of the BTO cuckoos that have been fitted with satellite tags, which tracks the adult birds throughout their lives, including during their migrations south.
Just as important are projects looking at nesting and chick survival, and here ringing of nestlings such as those at Cranwich comes into its own.
So there nestled deep within and completing filling a neatly woven nest, wrapped around the reeds, was a cuckoo. With longer sheaths on the feathers than any other chick I have seen, the cuckoo looks like a miniature porcupine.
|Me and my new friend, Spike!|
So far this year the survival rate of the nine cuckoo’s found at Cranwich has not been great, with only two having definitely fledged. Finger’s crossed this one survives…
|Safely nestled back in the nest, and ready for more food!|