Taking part

Heronries Census nest counts are made by BTO volunteers, including birdwatchers, reserve wardens, landowners and foresters. Help from people with special access to private or remote heronries is especially welcome.

Nests in deciduous trees are best counted
before leaf-burst in spring.

Coverage is coordinated through a network of regional organisers who match heronries to counters and try to avoid double counting. The first step in contributing to the Heronries Census is therefore to contact your BTO Regional Representative to ask whether there are known sites that need counters. If you know of a heronry, you could ask whether it already has a counter.

Making a count of 'apparently occupied nests' at a heronry is often very straightforward but is tricky when the nests are obscured by foliage. No specialised ornithological knowledge or experience is required. Clues such as droppings or hatched eggshells under nests can help observers decide whether a nest is in use. Access is needed under the nests or to nearby vantage points from which the heronry can be viewed. In many cases this may require landowners' permission.

Even if no nest count can be made, a report indicating whether or not the heronry is in use, and if so by which species, is valuable for monitoring.

Online data entry is not yet available for this scheme. Counts are submitted mostly on A6-sized cards, which are distributed by the survey's regional organisers and available by post from BTO HQ in Thetford, but can be accepted in any format.