Brown rats are on the increase in every region year on year in the UK, according to the recently published National Rodent Survey 2000, produced by the National Pest Technician’s Association (NPTA).

The survey and report were undertaken by the Association in response to two factors reported by members. Firstly, members in and around England and Wales were perceiving an increase in rodent activity country-wide, particularly with brown rat (rattus norvegicus) infestations. Secondly, figures published by MAFF in December 1999, based on surveys in 1996, suggested that generally rodent numbers were on the decline. NPTA members felt that the Government report had been overtaken by events and that in 1998 and 1999 numbers had been on the increase.

In order to provide up-to-date figures the Association sent a survey form to every District and Borough Council and Unitary Authority within England and Wales, seeking to provide trends, and asking for the 12-month figure for the last two complete years 1998 and 1999.

In the light of the success of the original survey and the trends it revealed, the NPTA extended the survey to include also Scotland and Northern Ireland. Following a speedy response the latest figures are included in the national survey published in November 2000.

Key points in the survey are that, whilst figures for individual local authorities varied enormously, the average UK figure showed an increase of 18% in brown rat infestations.

The average figure for house mice infestations across the UK showed a decrease of 2%.

Looking specifically at summer brown rat findings the survey shows that the average UK figure showed an increase of 31% in brown rat infestations, comparing the summer of 1999 to 1998.

The report comments that the pest control industry needs to examine carefully how the increase in summer rats in particular can be brought under control.

The report also notes that for decades the summer season has traditionally been known within the industry, and particularly within local government, as a quiet period for rodents generally and rats specifically. This has in the majority of cases enabled councils to tackle the traditional increase of insect infestations (ants, cockroaches, fleas and wasps) in the summer months from April to September.

Factors in increases

The NPTA highlights several key factors which it considers could play a vital part and should be part of a future agenda for discussion.

These include:

  • global warming, as a factor affecting climate patterns may be increasing the year-on-year figures in that it allows breeding cycles to increase
  • the general reduction of funding by the privatised water authorities in that routine sewer surveys and treatments are generally being reduced
  • in urbanised areas the continuing decay and lack of routine maintenance of old sewerage systems that allow rats to escape to the surface
  • the use of modern plastic building products, such as airbricks, pipework and drainage chambers, that allow rats to chew through them and thus enter buildings and homes
  • the proliferation of fast food outlets with poorer hygiene and rubbish standards being tolerated by councils and the general public
  • the reduction of pest control funding within local authority environmental health budgets

    The survey also highlights a growing concern about “second generation” poisons which may be developing resistance among rodents and there is also a view that legislation in this field is now outdated.

    The Association now plans to repeat the survey in June 2001 and in subsequent years.

    The NPTA has put its findings before the relevant authorities in local and central government and says that the increases found generally with brown rats need to be re-examined and considered carefully, particularly if councils are to achieve their new “best value” targets.

    In the longer term the Association sees that there could be need for more staff and financial resources if the trend in the rise of the rat population continues.

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