A Bucks Bittern 8th November 2017

Each year I make one or more trips to Calvert Lake in the neighbouring county of Buckinghamshire where I know I have a good chance of seeing a Bittern in the winter months.

Calvert Lake and its reedbeds

Bitterns are still a rare bird in Britain and it is always a thrill to see one of these ultra secretive birds. I am lucky to have not only the opportunity to see Bitterns here but also at my local RSPB reserve at Otmoor in Oxfordshire where, thanks to the diligence and efforts of the RSPB, a large area of reeds has been created which now provides a habitat in which Bitterns have bred for the last two or three years.

Bitterns were common in west and central Europe up to the nineteenth century. In Britain they were historically considered a gourmet delicacy and as a result became extinct in 1887, mainly due to hunting and to a lesser extent habitat loss. Presumably it was birds from Europe that recolonised Norfolk in 1900 and were proved to breed in 1911 with the population rising to 80 booming males by 1950 but then slowly declining to only 22 booming males in the 1990's. It got worse as the numbers reached a nadir in 1997, when prolonged freezing weather halved the population to only 11 booming males but since then, with enlightened conservation efforts, the population has risen, so that by 2017 no less than 164 booming males were recorded at 71 sites in England. (They are not found breeding in Scotland and Ireland) The main threat to Bitterns today in both England and Europe is degradation and or loss of their reed bed habitat by draining, drying out or conversion to agriculture and in Holland to this day, 90% of reedbeds are harvested, which removes suitable winter cover for Bitterns

They are therefore still an endangered and rare bird and probably always will be due to their particular and specialised habitat requirements but hopefully ongoing careful management of the remaining suitable reed beds and creation of new reed beds for both wintering and breeding, as well as supplemental feeding and maintaining ice free areas of water in freezing weather where Bitterns occur, will preclude any further declines and boost Bittern populations.

I got to the hide that overlooks the lakeside reed beds early and sat on a hard, cold bench in the damp, fusty smelling hide, looking out on a frosty morning but with the sun promising to soon rise above the trees on the far side of the lake. A group of four or five Long tailed Tits passed along the thorn hedge flanking the hide and out on the lake Tufted Ducks and Common Pochards were scattered about, either diving or sleeping. Coots were, as usual, forever bickering, flapping across the water, but never quite becoming airborne, intent on confronting another of their kin, their aggressive progress aided by their huge lobed feet that made a loud splattering noise as they ran across the surface of the lake, accompanied by mini explosions of staccato sound from their white bills. On the still air came the distinctive whinnying calls of Little Grebes, hidden at the outer edge of the reeds whilst a Water Rail gave voice from within one of the reed beds, its harsh squeals in discord with the grebe's calls. Cormorants growled and gargled as they perched on the rails of the  moored rafts, black and ugly as they stood to digest their fishy meals. The lake is never quiet or free from bird sound.

It often requires a long wait before a Bittern appears, if at all, and that can be a bit of a hardship sat in a small doorless hide whose spartan interior can become very cold. Sometimes the views are extraordinarily good, as it was last year when a Bittern stood in the open for over thirty minutes allowing me to examine it in every detail before it finally crept back into the reeds see here

At other times the views are the complete opposite, granting a glimpse of literally only seconds as it crosses a channel between two reed beds but does not stop.

Such was the situation today and after a two and a half hour wait, a Bittern slipped across the channel in the reeds to my right and was gone almost before I could raise my binoculars. Unlike a Grey Heron they do not walk with an upright body or held at an angle but hold their body and head almost horizontally creating a distinctive crouched silhouette.

The origin of the Bitterns that come to this particular location are open to conjecture with some suggesting they may be from the RSPB's reserve at Otmoor.  Possibly they are immigrants from further afield as numbers of Bitterns from Europe come to take advantage of our comparatively milder climate in winter and undoubtedly prolonged cold weather in Europe will drive others to Britain also, as this species is particularly vulnerable to extended periods of freezing weather.

I remained for five and  half hours in the hide during which time I saw the Bittern three times for all of four minutes. There was no showing off in the open today, not that I was worried, as just to see this rare and shy bird, no matter how briefly was reward enough. Bittern watching is tantalising, unpredictable and frustrating but ultimately often rewarding and I would have it no other way