Taking part

Grey Heron nests © Jan Pritchard

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

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.

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 to use the 'Register' button to contact your BTO Regional Representative. If you just want to make a general enquiry, or pass on some information, please email herons [at] bto.org.

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.

Counts can be submitted 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. Online data input is encouraged where possible.

Around two-thirds of all heronries in England, Wales and the Isle of Man are currently counted each year. Historically rather few counts have been made of heronries in Scotland and Northern Ireland, but support for the Heronries Census there has been growing fast in recent years. The number of active heronries counted in the UK is now well over 500 each year.

Health & safety

Heronries Census participants are asked to bear in mind that counting heronries can often bring risks to personal safety, and are reminded to minimise risk and take all proper precautions. The BTO's health and safety information, available here, should be studied before any fieldwork is started.

Once registered for this survey and allocated one or more heronries to count, you can input, view and edit your Heronries Census data online. Please login or register now, using the buttons above, to begin using the online system – or continue to use Heronries Census cards to submit your data, if you prefer.