Heronries Surveys

As a predator at the top of the freshwater food chain, Grey Herons are excellent indicators of environmental health in the countryside.

The Heronries Census began in 1928 and is the longest-running breeding-season monitoring scheme in the world. The aim of this census is to collect annual nest counts of Grey Herons Ardea cinerea from as many sites as possible in the United Kingdom. Volunteer observers make counts of apparently occupied nests at heron colonies each year. Changes in the numbers of nests, especially over periods of several years, are a clear measure of the population's trend. In recent seasons, observers have counted also the nests of Little Egrets Egretta garzetta, which are now appearing in a number of southern English heronries.

Coverage is coordinated through a network of regional organisers. A core of birdwatchers and ringers monitor their local colonies annually, providing a backbone of regular counts. Around two-thirds of the heronries in England and Wales are currently counted each year, with major censuses carried out in 1928, 1954, 1964 and 1985. Rather few counts are made of heronries in Scotland and Northern Ireland. Counts are submitted to the BTO on cards and the data are entered onto computer at BTO headquarters. The number of heronries cards submitted each year is around 450.

The latest of the periodic more-complete surveys was conducted in 2003 and consisted of three elements:

• Heronries Census counting of all colonies already known, or newly reported in 2003 (including Little Egret)
  
• a search of random squares for sites that would otherwise be missed
  
• detailed regular coverage of a sample of heronries, throughout the breeding season

If you would like to take part in this year's survey please contact your local Regional Representative or John Marchant (email: ) at BTO HQ

You can help by making a donation to the Heronries Appeal.
£40,130 has been raised (as of 01/09/05). Thank you.