C. Our first direct understanding of the habitat needs of breeding bitterns came from comparisons of
reed bed sites that had lost their booming birds with those that retained them. This research showed that
bitterns had been retained in reed beds where the natural process of succession, or drying out, had been
slowed through management. Based on this work, broad recommendations on how to manage and
rehabilitate reed beds for bitterns were made, and funding was provided through the EU LIFE Fund to
manage 13 sites within the core breeding range. This project, though led by the RSPB, involved many other
organisations.
D. To refine these recommendations and provide fine-scale, quantitative habitat prescriptions on the
bitterns preferred feeding habitat, we radiotracked male bitterns on the RSPB’s Minsmere and Leighton
Moss reserves. This showed clear preferences for feeding in the wetter reed bed margins, particularly within
the reed bed next to larger open pools. The average home range sizes of the male bitterns we followed
(about 20 hectares) provided a good indication of the area of reed bed needed when managing or creating
habitat for this species. Female bitterns undertake all the incubation and care of the young, so it was
important to understand their needs as well. Over the course of our research, we located 87 bittern nests and
found that female bitterns preferred to nest in areas of continuous vegetation, well into the reed bed, but
where water was still present during the driest part of the breeding season.
E. The success of the habitat prescriptions developed from this research has been spectacular. For
instance, at Minsmere, booming bittern numbers gradually increased from one to 10 following reed bed
lowering, a management technique designed to halt the drying out process. After a low point of 11 booming
males in 1997, bittern numbers in Britain responded to all the habitat management work and started to
increase for the first time since the 1950s.
F. The final phase of research involved understanding the diet, survival and dispersal of bittern
chicks. To do this we fitted small radio tags to young bittern chicks in the nest, to determine their fate
through to fledging and beyond. Many chicks did not survive to fledging and starvation was found to be the
most likely reason for their demise. The fish prey fed to chicks was dominated by those species penetrating
into the reed edge. So, an important element of recent studies (including a PhD with the University of Hull)
has been the development of recommendations on habitat and water conditions to promote healthy native
fish populations