The BTO Heronries Census is not only one of the longest running BTO surveys, dating back to 1928, but also the longest-running monitoring dataset for any breeding bird in the world. The annual census is backed up with periodic, wider surveys (the last in 2003) and it is with this in mind that we are launching a Heronries re-Survey in 2014. We’re aware that several heronries in the county may well be occupied but currently unrecorded, so will aim to revisit all historic breeding sites in the county and confirm their current status.
At the moment, we are aware of 17 heronries that have been active in the recent past (shown by the ‘drop’ symbol on the map below) and 21 in the more distant past (shown by closed blue circles below) but we will aim to cover all of these sites in 2014. There are also 14 sites officially recorded as extinct (shown by closed pink circles below) which might be worth a revisit.
During 2014, the regular BTO Heronries Census volunteers will continue to record their sites as normal and the priority for the additional sites will be to revisit those where breeding was positively recorded in recent times, although obviously it would be desirably to have complete coverage if possible. The methodology of the re-Survey will follow that of the Heronries Census, so nests should be counted in the second half of April, but it would be advisable to make an earlier visit when reduced leaf-cover will allow a better assessment of occupation. For those sites that are occupied, we will just need a count of the number of ‘definitely occupied’ nests on each date and also an estimate of the number of pairs likely to be using the site.
The interactive map below (double-click to zoom in) shows all of the sites we hope to cover, so if you are able to visit any of these then please email the survey organiser in advance for details of what to record, Mark Grantham (firstname.lastname@example.org).