HL Deb 03 June 2003 vol 648 cc150-1WA
Baroness Miller of Chilthorne Domer

asked Her Majesty's Government:

Further to the Written Answer by the Lord Whitty on 10 March (WA 152), what evidence they have that song thrushes are in decline in United Kingdom gardens. [HL2868]

Lord Whitty:

The best figures on song thrush numbers in gardens come from the RSPB's long-running "Big Garden Birdwatch". From 1979 to 2003 there was a decline of 31.1 per cent in the mean number of song thrushes recorded in each garden taking part in the survey. Comparing 2003 with 1985 (when the survey was carried out much more regularly), the decline is 57.1 per cent. These figures show that the decline in numbers occurring in gardens is similar to the overall national trend during the same period. There is the suggestion that the decline since 1985 in gardens has been greater than the national trend but a more detailed anlaysis of the data would be needed to confirm this.

The BTO has carried out a garden bird survey "Garden Birdwatch" since 1995 which suggests that song thrush numbers in gardens have been roughly stable in the period 1995–2003, a trend mirrored by national Breeding Bird Survey data from all habitats.

Baroness Miller of Chilthorne Domer

asked Her Majesty's Government:

Further to the Written Answer by the Lord Whitty on 10 March (WA 152), what work they are dong to establish whether increased usage of slug pellets in gardens is having an impact on the United Kingdom song thrush population and on other birds and mammals, especially those whose habitat is mainly gardens. [HL2870]

Lord Whitty:

The Pesticide Safety Directorate has published reviews of methiocarb (1998) and metaldehyde (1996), two of the major components of slug pellets. The report for methiocarb raised concerns regarding the effects on small mammal populations and noted a high risk to mammals. Methiocarb has high acute toxicity to birds, but considered the risks of direct poisoning of birds from slug pellets quite unlikely because of the repellants used in their manufacture. Metaldehyde was considered to pose a high risk to small mammals and birds from primary and secondary poisoning. Acute poisoning of birds can therefore result from slug pellets, although the number of recorded incidents is relatively few.

Methiocarb does however pose a high risk to some non-target invertebrate populations. As a result, slug pellets, along with other broad-spectrum insecticides, may have contributed to observed declines in farmland invertebrate populations, which include prey items for farmland birds.

Such potential indirect effects of pesticides acting on bird populations via changes in their food supply are not currently considered during pesticide registration. However, the Pesticide Safety Directorate has established a subgroup of the Advisory Committee on Pesticides, currently chaired by English Nature, with the aim of proposing methods for assessing wider biodiversity effects of pesticides.