As a follow up post on the previous post Tim Ball writes:
For a number of years we have been monitoring and ringing breeding Marsh Harriers and a group of watchers have been carrying out co-ordinated monthly counts of the winter Harrier roosts which frequently contain both Hen and Marsh Harrier. No-one really knows whether some or all of the local breeding population stay for the winter or whether the breeding birds move out and different birds visit for the winter. Despite ringing over 150 chicks we have had very few recoveries but even these give a snap-shot of the birds’ movements with records from Cambridgeshire, Cornwall and France.
In 2009 Rod Smith and Swale Wader Group started a wing tagging project in an attempt, amongst other things, to establish the extent of the link between the breeding and winter populations of Marsh Harriers. Ten birds were tagged in 2009 (white tags on both wings) and due to a significant increase in effort and some great help from other Harrier watchers we've tagged 28 in 2010 - 25 on Sheppey (blue on the right wing) and 3 in the Stour valley (red on the right wing).
This autumn and winter we have had a good run of reports showing just how mobile these birds can be. Blue 13 was ringed in June 2010 and seen twice on the Isle of Wight on 15 August, rather than head over to the continent it went north and was reported at Frampton Marsh, Lincolnshire on 14 September. We’ve also had reports from Essex (at least 4 different birds), one in London, and Blue 30 was in north east Lincolnshire in early September. Blue 14 has been seen back on Sheppey in the last few days after an October excursion to the Dungeness area. No less than 4 different birds have been seen in the Strumpshaw Fen area - including Blue 36 which been there from 14 September to at least 28 January.
Full details of the project are on the Swale Waders web site – www.swalewaders.co.uk, it’s too early to draw many conclusions but as you can see we’re already getting some interesting results.
Thanks to Tim Ball and Martin Beach for the photos.