Publication in 1930 of Bernard Riviere's magnum opus 'A History of the Birds of Norfolk' marked the commencement of almost three decades of steady increase in the numbers of the skulking and ever secretive bittern. During this period despite sea-flooding and a succession of severe winters booming males reached a peak in the mid 1950s. At that time the county population was of the order of 60 booming males.
It is now known that each boomer has his own distinctive voice. This discovery would have been invaluable all those years ago in assessing the true numbers.
The first misfortune to beset the Norfolk bitterns was a tidal surge in mid-February 1938 which swept over the shingle ridge at Cley flooding the reserve to a depth of five feet. The coast road, under two feet of water, was impassable to traffic for a week. The warden's diary described the marsh as 'bereft of all birdlife except bitterns which presumably fed on eels'.
Fortunately four bitterns remained at Cley and one nest was successful.
In Broadland the storm resulted in a 2000 feet breach in the sandhills at the Hundred Stream north of Winterton. The flooded area extended to 7500 acres, the depth varying from a few inches to over eight feet in the deepest parts. Only three bitterns nests were found that spring in the affected area, 'birds being absent in areas where they had bred and boomed for the past 20 years.'
These enigmatic birds
faced further problems during three consecutive severe winters beginning
in 1940. Worse was to follow: 1947 is still remembered as outstanding
for the intensely cold, long, winter. Periodic blizzards buried all reedbeds.
A number of bitterns died of starvation, but the survivors bred successfully
both at Cley and in the Broads.
What are a bittern's ideal needs and how can Continental ones wintering here be tempted to say and breed? According to the authoritative 'Birds of the Western Palearctic' bitterns favour the dense cover of reedbeds contained sheltered shallow water...usually avoiding older and drier stands of reed...and tolerating brackish water where the sea has broken in.
Fortunately concerted action has been taken to rescue the bittern from the brink of extinction as a breeding bird. The Norfolk Wildlife Trust has joined the RSPB, English Nature and the Environment Agency in a series of ambitious projects to, not only restore reedbeds but also to create large new ones. The work involves providing areas of open water with reed fringes, widening dykes and constructing banks to raise water levels. It would be a tragedy to again lose nesting bitterns as happened by the middle of the last century.
During the years of abundance the country's leading bird photographers came to Broadland. Sitting in tiny hides for long periods, they were privileged to observe the domestic life of the mysterious bittern. Their photographs confirm it was frequent to find nests in deeply flooded reedbeds with water lapping the nest edges. One Hickling nest was built on the top of an abandoned coot's nest and in water so deep that the keeper had difficulty in reaching it clad in thigh waders.
Normal progress of a bittern is performed not on the ground but by grasping reeds - several at a time - with the huge toes. This stilt-like movement is remarkably effortless for so comparatively large a bird.
In times of a shortage of food nestling bitterns will turn cannibal and devour the smallest in a brook. One young bird, handled after wandering, readily disgorged a leg and thigh of a former brother or sister.
For many years male
bitterns have been considered at times bigamists. In a single season at
Hickling three nests were very close to each other with only a single
boomer in the area. Additional males would have been stabbed to death.
Recent studies in Germany confirm that a male bittern can have up to five
By Michael J. Seago