Waders Need Undisturbed Roosts

News from the BTO
16th June 1996

Writing in the current issue of BTO News, the newsletter of the British Trust for Ornithology, Mark Rehfish reports on research which may lead to our wintering waders having an easier time surviving the winter. It was based on careful analysis of more than 250,000 waders ringed on the Wash (Norfolk/Lincolnshire) over almost 40 years.

English Nature, as part of its Estuaries Strategy, wanted to see whether it was feasible to establish safe areas for waders to roost without any disturbance. Although these birds may fly thousands of kilometres to Britain for the winter disturbance at roosts can cost them up to 1.8% of their total winter energy requirements if they are forced to fly 3 kms to an alternative - or 5.9% if they have to go 10 kms. This extra energy expenditure may be critical especially when they have to cope with the limited feeding available for them at neap tides.

The analysis showed that even over the extensive mud-flats of the Wash the birds were very faithful to their own roosting sites. Young birds were rather more likely to move sites but the adults were faithful even between years. The least mobile species on the wintering grounds was the Siberian Grey Plover. By analyzing the complete data in relation to the whole Wash it was estimated that 13 different refuges, at 7 km intervals, around the Wash would be sufficient to ensure they had a safe and secure winter.