Saturday, 23 June 2012

Lush growth shelters nesting birds

Even with such disappointing weather, the vegetation has become lush and luxuriant. Dense stands of nettles, punctuated with the taller branching stems of umbellifers, carpet much of the ground in the scruffy margins of damp fields and along the edges of woodland rides. I really notice the extent to which the vegetation has developed because of my regular visits to the same bits of habitat to check on nesting birds found earlier in the season. Nests that appeared rather exposed earlier in the year are now cloaked with verdant growth, something that can make them difficult to relocate if you do not take careful notes.

One particular patch of habitat, just to the side of a busy footpath, provides cover for a nesting whitethroat and also, I suspect, a chiffchaff. I found the former nest a couple of weeks ago, when movement through the patch was easy enough and I have a track by which I can return to the nest. I say ‘track’ but it is more like a series of stepping-stones, my movements carefully placed to avoid attracting unwanted interest to the nest. The chiffchaff has nested more recently and, while I have a good idea of where the nest is located, I will not make an approach for fear of damaging the nest woven into the vegetation.

The whitethroat nest is barely 20 centimetres off the ground, wedged into grass and dead umbellifer stems and beautifully hidden from predators. It would be all too easy to overlook. Over the years I have learnt that nettles and grasses can be parted with two sticks to leave little evidence of your visit and that bramble can be worked in a similar manner and that it quickly springs back into place. However, any piece of vegetation bound together with cleavers is best left untouched.

The whitethroat was incubating four eggs on my last visit and these are due to hatch any day now, my next visit timed to make a count of the number of youngsters that emerge and to provide a good indication of the date on which I should return to ring the young. The chicks grow with alarming speed and just a week after hatching they will be too large be to approached, the young likely to scatter from the nest as they would do if approached by a predator. I once witnessed the advantages of this strategy when attracted to a bramble by the harsh alarm calls of a whitethroat pair. Wrapped around a bramble stem, with its head in the empty nest, was a grass snake; the chicks were scattered elsewhere around the bush, out of danger but still able to attract a parent in with food.

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