Boom time for bitterns thanks to intervention
MANY bird species are in urgent need of help, and more are joining the list of those in trouble than the list of those that have recovered, the balance may be tipping. In times of economic uncertainty, money must be used with great care.
It’s clear that some species need more help than others but, my friends at the RSPB are increasingly tasked with a big decision. Which species to help first and where will any money be best spent. To this end the organisation developed a species recovery strategy, where they identified the scarce birds which are struggling but also those which are not currently declining, and in particular where a significant proportion of the population was on RSPB nature reserves.
For example, a great deal of time and money has been spent on rarities such as the Hen Harrier.
This is largely in the field of education and the highlighting of illegal bird of prey prosecution.
On the other hand, the RSPB have not taken its collective eye off the ball, so to speak, with birds like the Bittern, which is doing well in the reed beds of Leighton Moss and other reserves. Once common in wetlands, bitterns became extinct as breeding birds in the UK in the late 19th century, as a result of wetland drainage and hunting.
These birds were next recorded as breeding in Norfolk in 1911. They slowly re-colonised from there and by 1954 there were around 80 booming males. However, numbers dropped again as their reedbed habitats became drier through lack of management. By 1997 only 11 booming bitterns were recorded in the UK and there was a similar pattern of decline in bitterns across western Europe. Alarmed by the plunging bittern numbers, the RSPB started a research programme to investigate the needs of this previously littlestudied bird. This led to some clear management recommendations that have been, and still are being, implemented at many sites in the UK.
Bitterns are difficult to study as they are found in low densities in habitats which are difficult to work in. The research looked at the habitat that bitterns prefer, their feeding requirements, the home range of male bitterns, as well as female nesting requirements, chick diet and their dispersal.
To find this information, lightweight radio-transmitters were attached to bitterns at two RSPB reserves so that their movements could be tracked. Later, young birds at the nest were also radio-tagged and their food preferences studied.
Management work to date has stopped reedbed degradation, and the projects under way should provide significant areas of high-quality reedbed in the future. However, it will take many years for these new sites to mature.
The knowledge that the RSPB has gained about bitterns’ needs, as well as how to manage and create reedbeds, is being shared among those managing reedbeds.
Overall, the prospects for UK bitterns appear to be good, however, the RSPB’s aim is to plan ahead and factor in future possibilities which may affect the birds, for example climate change.
If sea levels rise, saltwater could flow into coastal reedbeds, making the habitat unsuitable for bitterns. As a result, several new reedbeds are being created inland, away from vulnerable coasts, such as Lakenheath Fen in Suffolk and the Hanson–RSPB Wetland Project in Cambridgeshire, where five square kilometres of reedbed are planned.
The nearest bitterns for readers are at Leighton Moss, Silverdale, in Lancashire. This is one of my favourite reserves, not least because I’ve been lucky enough to spot a bittern every time I visit but, their neighbours are pretty attractive too: including marsh harriers, beared tits, peregrines, otters, avocets and red deer.
●●An adult bittern (Botaurus stellaris) wading in a reed bed at Lee Valley Country Park.