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Scheming cuckoos pick foster parents carefully As you look up to Ilkey Moor from the town, you can see that the moor is coming alive. Bright patches of light green and ochre, the new growth on the great clumps of bilberry, stand out cheerfully against the dull russet of old bracken. On a recent sunny afternoon, we took a walk up by the Swastika Stone to enjoy this annual treat. Close up, we could see the pink, bell-shaped flowers already there among the new bilberry leaves, a great magnet for insects, particularly bees and hoverflies, ready to trade pollination for a taste of nectar. The lower slopes of the moor are dotted with isolated trees, mainly rowan. Each one had been claimed as a convenient song post by a male willow warbler and they were all singing lustily. The wistful little song is quite easy to recognise, a flurry of notes which trails away into silence, and, if you look carefully you may catch sight of the singer, a tiny bird, olive green above and a lighter yellowy-buff below, with a distinctive eye stripe. We once had to rescue a willow warbler which had accidentally flown into the house - in the hand it weighed no more than a crumpled tissue and yet it flies all the way to West Africa and back in a year. Now, here they all were, establishing their territories by exchanging songs with neighbours dotted across the hillside and below on the fringe of Hebers Ghyll woods. The other birds which caught our attention were meadow pipits: small, brown, rather insignificant birds newly arrived from their upland breeding grounds, which establish their presence by flying high into the air and then parachuting down again, singing all the while. They make their nests on the ground and usually raise two broods. Meadow pipits are our most common small moorland birds and form the main prey of another summer visitor to our uplands - the merlin. It may be the smallest of our British birds of prey, but this little falcon is as spectacular as a peregrine as twists and turns in pursuit of its prey. Though fairly uncommon, the merlins seem to be holding their own in Wharfedale. They nest on the ground and so are particularly vulnerable to predation and to bad weather; heavy rain at the wrong time can destroy their breeding hopes for the year. The other main exploiter of the meadow pipit population has found an ingenious solution to this problem by not putting all its eggs in one basket, or rather, one nest! As usual the first cuckoo arrived on Ilkey Moor at the end of April and the males can be heard shouting out their familiar call. Soon the females will be busy staking out the local pipits' nests, waiting until the clutch is complete; then nipping in and laying an egg in each, carefully removing a pipit's egg as she leaves. Cuckoos choose their foster mum carefully. Their egg mimics the colour of the one it replaces and is timed to hatch first. And in an amazing feat of strength, the baby cuckoo squirms around until it has tipped out all its potential rivals and can thus enjoy all the parental care for itself. And pipits make excellent parents. [Back] |