Friday, 23 July 2010

Bigger is better

A super Bittern pic by Steve Blain, an old Bittern nest and Small Red-eyed Damselfly

The week marked the start of a period of work assessing the quality of many of the best reedbeds around the country. How are they performing for birds and Bitterns in particular? This largely involves wading through reedbeds getting wet, smelly, hammered by mosquitos and cut to shreds by reeds.

We started at Ham Wall in Somerset. More correctly, we started by looking for the nesting Little Bitterns. Sightings had now become infrequent as it appeared that feeding flights to the nest had stopped. There were two brief views of the female. However, sightings by visitors of ‘small brown bitterns’ in the vicinity suggested that the young have fledged.

Fifteen years after the reedbed creation started, Ham Wall now supports more Bitterns that any other UK reedbed - a remarkable success. This year there were 8 boomers and at least 8 nests, with a further 7 boomers in the wider area. This success is undoubtedly partly due to the size of the site. At over 200 ha, this is a large reedbed. It is clear that these bigger habitat creations are performing better than smaller sites. It is also a very wet reedbed, with around a metre or more of water in the reedbed areas chosen for nesting by the Bitterns. We record habitat details (water depth, reed height and density etc) around old nest sites in order to further our knowledge of replicating these conditions in new sites being developed.

Ham Wall is formed from ex-peat diggings, now restored to wetland habitat by careful land-forming. Fish and amphibian populations are now exceeding the threshold for Bitterns, hence the recent surge in breeding birds. This site now forms the standard that all others have to match.

A number of Bitterns were seen during the visit, as well as Great White Egret, Bearded Tit, Marsh Harrier, many Cetti's Warblers and good numbers of Small Red-eyed Damselflies.

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