Friday, 2 January 2015

Old nests revealed

Clearing the young alders that have sprung up across one of our local sites is hard work. Each of the young trees, and there are many hundreds of them around each of the old pits, has to be cut low to the ground and then treated with a chemical to kill the roots and prevent regrowth. The work is being done to prevent this non-native form of the tree from shading out the important wetland and reedbed habitats that are such an important part of the site.

It is while clearing the reed litter and moss from around the base of the trees that we have turned up the nests of reed buntings, long empty remains of the now distant summer. Reed buntings are common on the site and tend to nest around the margins of the old gravel pits. The nests are invariably built within thick cover, placed just off the ground and hidden beneath an overhanging piece of vegetation. The nest itself is a bulky cup of sedge and grass, lined with finer stems and, sometimes, hair or reed flowers.

We sometimes find reed bunting nests while looking for those of other species but they can also be found by watching the female as she returns to the nest. This is not always as easy as it sounds, especially when the nest has been placed in a sedge bed that is uniform in appearance. Many of the nests are found while the female is incubating. The eggs, like those of our other bunting species, are marked with lines and squiggles, as if an artist has been given free rein to decorate them.

The placement of the nests, well-hidden within the thick vegetation, should afford them some protection from the attentions of nest predators, but we suspect that they still suffer quite high losses, with both otter and grass snake present on this particular site. If a nest is lost then there is still a good chance that the birds will get some young off later in the season. Each pair may make two or three nesting attempts over the summer. That we’ve been finding so many old nests might suggest a healthy population at this site and a run of nesting attempts.

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