On the 8th May 2000 a brood of Bitterns were ringed at Leighton Moss by the RSPB Research Staff, they were sexed using DNA technology. In the years since then ringed Bitterns have been seen regularly at Leighton Moss. It was thought that only one bird had survived for the ring numbers could not be read.
However with the recent advances in digital photography and digiscoping it has been possible to read the ring numbers and it has now been definitely proved that there are two ringed Bitterns, both female on DNA evidence at the time of ringing.
1291703 has been only seen from the Jackson and Griesdale Hides at the western end of the Reserve. It appears to be the female that has nested in this area for several years. Its sibling 02 (see photo) has only been positively identified from the Lower and Public Hides at the eastern end of the Reserve. So it appears on present evidence that these two birds have different ranges within the reserve. 02 has only been positively identified between late autumn and early winter. However Elaine and Eddie Prince saw a ringed bird at the Lower Hide on July 5th 2007 but could not see the critical part of the ring. Also on 28th September 2007 they saw two ringed Bitterns at the Lower Hide on an occasion when the Jackson and Griesdale meres were disturbed by Reserve staff undertaking habitat management work but no details of the rings could be seen.
It is amazing that both these females have survived so long and at 8 and a half plus years they are the oldest Bitterns recorded by the British Ringing Scheme. One rather worrying aspect is the question as too what extent there is inbreeding within this tiny and isolated population.
Many thanks to all those observers who have photographed or observed the birds. Please continue to pass any sightings to the reserve staff.
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