Rudd-y good news for bitterns
PUBLISHED: 17:19 15 February 2010 | UPDATED: 15:42 20 February 2013
Herts and Middlesex Wildlife Trust takes a closer look at bitterns and how they have been kept happy with the introduction of some new fish...
THOUSANDS of small fish have been released into lakes on our nature reserves in the Lee Valley this autumn in an effort to conserve the bittern - a small brown heron and one of Britain's rarest birds.
Up to seven bitterns spend the winter months living in reedbeds in the Lee Valley where they feed on small fish. At Amwell and Rye Meads Nature Reserves, rudd were introduced to establish breeding populations of fish as food for bitterns. The increased populations of fish should provide the bitterns with sufficient food throughout the year, and eventually encourage the birds to stay and breed here. Rudd's surface feeding behaviour means they are easily caught by bitterns which feed from the edges of reedbeds.
It is thought that by the end of the winter, fish stocks have usually fallen to such low levels that the bitterns find the area unsuitable for breeding. They therefore fly to other parts of the country - particularly East Anglia and Lancashire - to seek out the food they need. HMWT has spent many years managing Hertfordshire's reedbeds to create the right conditions for bitterns and we are now working to ensure that they have enough food to thrive here.
Such is the bittern's rarity that a special action plan has been written for them in Hertfordshire. Herts and Middlesex Wildlife Trust co-ordinates the implementation of the plan with other conservation organisations. The Environment Agency (EA) provided funding for the purchase of the rudd.
Amwell Nature Reserve near Stanstead Abbotts provides one of the best opportunities to see a bittern. Bitterns can normally be seen feeding along the edges of lakeside reedbeds. Last year, the first individual of the season was spotted at Amwell in mid November.
Short back and sides for reedbeds
This autumn the reedbeds on one of our nature reserves got a well-needed spruce up from a specialist piece of machinery. The Truxor, an amphibious mowing machine, came to Amwell Nature Reserve to improve the structure of the reedbeds for bitterns. This was to ensure that the recently introduced rudd are accessible to feeding bitterns. From reedbed surveys carried out by us, we knew that they could provide better conditions for these rare birds. Bitterns feed by standing within the edges of reedbed and watching for small fish which swim by through the reed stems. The birds catch the fish by striking forward rapidly into the water. By increasing the reedbed margin, we could create more areas for bitterns to fish from.
The Truxor was manoeuvred to cut channels and pools within the reedbeds which will attract fish from adjacent open water to seek refuge. The bitterns will fish among these channels and pools.
The Truxor is a Danish machine which has been developed specifically to harvest vegetation in water. A special cutting bar can be interchanged with a rake attachment which collects the floating, cut vegetation. This cut reed material can then be disposed of.
In addition to the work at Amwell, HMWT also offered advice to British Waterways when similar works were carried out by the Truxor at Marsworth Reservoir in Tring.