An investigation is under way as to why populations of the wading bird the lapwing have collapsed by 50 per cent over the last 30 years.

Gone are the days when farmland throughout Wiltshire would see huge flocks of the attractive bird arrive in winter. Although flocks of up to 150 can still be seen at Coate Water and other nature reserves around the county, the bird, also known as the peewit or green plover, is in sharp decline.

The Game and Wildlife Conservation Trust, in collaboration with the RSPB, will study 120 sites across arable landscapes in Hampshire, Wiltshire, Dorset, Cambridgeshire and Norfolk in a bid to find the answer to the decline.

Dr Andrew Hoodless, a wader scientist with GWCT, said: “Lapwings are very adaptable birds and because they nest on wet grassland, upland moors or arable land they should be doing quite well. But they are not.

“We know that the problem is not over-winter survival, but that the lapwings are simply not fledging sufficient chicks each year to maintain a stable population.”

The Government already pays farmers to leave bare patches of soil within cultivated winter cereal or oilseed rape fields. But research in 2010 and 2011 found the plots were not doing enough to halt the decline.

Dr Hoodless said: “Farmers are paid to maintain the plots under agri-environment schemes and we therefore need to be sure that this is money well spent.

“To do this, our research aims to quantify how many chicks are fledging each year and whether the fallow plots are either maintaining stable populations or increasing lapwing numbers.”

Next spring the study will involve extensive radio tracking of lapwing chicks to identify what happens to them once they leave the nest.

Dr Hoodless said: “The radio tracking will provide more detail on chick requirements for food and cover for predator avoidance.

“Our aim is to provide well-researched solutions, to enable government to tweak its schemes, so that farmers can maximise habitats that help to boost lapwing numbers in the future.”

A spokesman for Wiltshire Ornithological Society said that, although he didn’t have recent figures on lapwing populations in the county, he could confirm that the numbers of the birds in Wiltshire had dropped by at least 50 per cent in the last 30 years.