An article entitled "Song thrushes silenced as farmers' slug pellets wipe out diet of snails", which appeared in The Times for 6 November 1996, alluded to a study by the British Trust for Ornithology funded by the Royal Society for the Protection of Birds. The RSPB has produced a note about the song thrush research which concludes that there are no grounds for suggesting that molluscicides are specially implicated in song thrush decline. The research is still taking place and there are no preliminary findings as yet. The full text of the note is reproduced below.

"The most up to date data on population declines (from BTO Common Birds Census) are for the period 1969-1994: 73% decline on farmland, 50% decline in woodland.

"Analysis of ringing data by the BTO and funded by the RSPB shows that there has been no trend over a similar period in adult survival rates but that survival of first year young has declined significantly from an average of 48.4% prior to the decline to 40.5% in the years 1975-1993.

"Analyses of nest record card data by the BTO has shown no evidence of decreased nesting success (egg or chick survival) over the period of decline.

"Analysis of CBC data by BTO and funded by RSPB shows that declines in density have been most severe on arable farms and that the declines have continued on arable during the 1990s, but not on mixed or grazing farms.

"Literature and current RSPB study show that snails are an important item in the diet at certain times of the year. These appear to be mainly taken from "non-cropped" habitats (gardens, hedges, woodland).

"The decline of the song thrush has been attributed by a variety of individuals to a variety of different factors including: loss of hedgerows, switch from pasture to arable, changes in timing and methods of cultivation, domestic cats, magpies, crows, sparrowhawk, road traffic, molluscicides, pesticides in general, hunting pressure on the Continent.

"Although none of these have been conclusively ruled out, the RSPB believes that, as with other declining farmland bird species, agricultural factors are most likely to be involved and has targeted its own research in this direction.

"MAFF Pesticide Usage Survey data show that, over the period of decline of the song thrush and other declining farmland species, there has been an increase in the area treated with molluscicides.

"RSPB is unaware of any data showing whether or not there have been major declines in snail and slug populations.

"At present RSPB believes that there are no grounds for suggesting that molluscicides are more or less likely to be implicated in the decline of song thrush than any of the other agricultural factors suggested above. We hope our research will help us to pinpoint the key factors."