Buttle, bog blutter, myre dromble, bull of the bog; the bittern has been known by some amusingly descriptive names in different parts of the country. Butter bump seems to have been its provincial name in the fens in the 19th century, as captured in Lincolnshire dialect in Tennyson’s ‘Northern Farmer: Old Style’, where the haunting sounds from the ghost of a murdered gamekeeper are likened to the bittern’s booming call:

“Theer wur a boggle in it, I often ‘eärd ‘um mysén; 

Moäst loike a butter-bump, fur I ‘eärd ‘um about an’ about, 

But I stubb’d ‘um oop wi’ the lot, an’ raäved an’ rembled ‘um out” 

The boom of a bittern must have been a rare sound when Tennyson wrote the poem; just twenty years later by 1885 the bittern was extinct in the UK, hunted as a delicacy, according to Bingley (1803) in the reign of Henry VIII it was “held in great esteem at the tables of the great” and its long and slender hind claw was “often set in silver and used as a tooth pick”. At least bitterns went down fighting:

“When caught, it exhibits much rancour, and strikes chiefly at the eyes of its antagonist. When wounded by the sportsman it often makes a severe resistance. It does not retire, but waits his onset, and gives vigorous pushes with his bill, as to wound the leg even through the boot.”

William Bingley (1803), ‘Animal Biography Volume 2‘

Bitterns returned to Britain as breeding species the following century and populations began to recover, only for the loss of its wet reedbed habitat to reduce it to just eleven booming males by 1997. Restoration of habitat has seen numbers slowly rise again, with birds surveyed every year to record the number of booming males and nesting females. I was grateful to join a survey this year at Ouse Fen, a former sand and gravel quarry being restored to a nature reserve, including plenty of wet reedbed.

Surveying bitterns involved sitting on a high seat waiting for the elusive bog-jumper to rise out of the reedbeds, tracking its flight and recording it on a map of the reserve. I can’t remember the last time I sat still for over four hours just looking at the countryside in front of me, and I enjoyed it so much that I’d probably still be up there now if the wardens hadn’t come to collect me in the afternoon. I was happy to have recorded eight flights during that time, although a seasoned surveyor on the other side of the reedbeds spotted eighteen! It will apparently take several further surveys to determine if and where nesting took place. No doubt bittern chicks are called baby boomers.

Now I don’t know of any colloquial names for cattle, but I’d suggest boot botherers and seat sniffers going by the attention given to me and the high seat I was perched on by the herd grazing the banks around the reedbeds. They didn’t stick around for long though – it was just a beef encownter.

During the nesting season, work on the reserve moves away from areas that might disturb the birds, and focuses more on the upkeep and maintenance of the infrastructure. As anyone with a lawn will appreciate, one of the most frequent tasks is to keep the grass well mown, particularly around the areas visitors use; the hides, benches, signage, pathways and gates.

Volunteers need to be certified to use the strimmers, mostly to learn how to maintain and use the equipment safely, but it also pays to give attention to comfort; the strimmers are reasonably heavy bits of kit when worn for several hours, and properly adjusting the harness can be the difference between aches and pains the following day. I’ve visited reserves often without appreciating that an army of volunteers work hard to keep them accessible, and it’s rewarding to now be involved.

Then there are areas not open to the public which nevertheless require attention. This is ‘Pig Field’, a field which hasn’t been pasture for a few years but will soon be open to a small herd of cattle. The electric fence was weighed down with well-established thistles, rushes and grasses and needed clearing to work effectively prior to the introduction of the cows. It was a pig of a field to strim on a hot day when we’d have preferred to have been in t-shirt and shorts, but had to wear full covering as we obliterated the thistles. Our reward was stopping for lunch and seeing a roe deer and red kite, soundtracked by cuckoos and a Cetti’s Warbler.

It helps that we have use of a neat little RTV to carry the strimmers, petrol (strimmers are thirsty!) and other tools between sites that need attention – meet Kubo!

There’s a 1950 animation called Foiling the Fox which follows the attempts of Sylvester the fox to have a lamb for lunch, always outwitted by our hero a canary called Dingbat. Without recourse to heroic canaries, the wardens at Fen Drayton Lakes have to come up with their own measures to outwit foxes and other predators like badgers, stoats, weasels, rats and other birds – tern chicks are vulnerable to gulls, raptors and corvids.

As foxes can swim (I was surprised to learn), even the nesting rafts and islands aren’t safe, so these are protected by outer ditches and fencing around the lakes, floating barriers around the islands, and chick shelters on the rafts – upturned halves of pots, or small wooden tunnels that chicks can run under to hide from overhead threats. The floating barriers are large buoyant rings of material, anchored down around islands, to foil foxes as they typically find them difficult to climb over.

This year an ingenious solution is being tried, replacing the cumbersome floating barriers with a simple rope, with small floats secured by pig rings at regular intervals and anchored down with bricks.

The hypothesis is that as foxes will not attempt to swim under barriers, and can’t climb over obstacles from a swimming position, even a rope on the surface of the water should be enough to foil the fox. If this is validated, it would save hundreds of pounds in materials, and make maintenance much easier.

What pleases me most is these measures don’t harm the predators, just aim to foil them. Foxes are handsome creatures I don’t often see, but just a few days later I came face to face with this one on the guided busway that leads to Fen Drayton Lakes from Cambridge. I couldn’t see its nemesis, the canary.

When I started volunteering with the RSPB at Fen Drayton Lakes reserve this year, one of the first jobs I got to help out with was repairing the nesting rafts, prior to the impending arrival of Common Terns from their wintering grounds on the west coast of Africa.

“There is a season, tern, tern, tern”

The Byrds

After a few years in the water the rafts were in need of repair, so we removed the rotten wooden frames, stripping it back to the main structure.

From here we (me, a hardy handful of long-serving volunteers, and the Assistant Warden) built up the the raft, adding the polystyrene foam buoyancy, and pop riveting plastic side panels in place of the old wooden ones, so the raft would be more hard-wearing in the water.

The following week we returned to complete the job, adding guttering to the side to act as ramps for chicks that jump overboard, then shovelling one and a half tons of gravel over one large and four smaller rafts. The rafts would be dragged in to place at a later date, and the finishing touches added – upturned halves of terracotta pots or wooden tunnels giving the chicks have somewhere to hide from overhead predators.

According to Simon, Assistant Warden at Fen Drayton Lakes, timing is key to the success of tern nesting on the raft. Ideally, the rafts will attract both terns and black-backed gulls, the gulls providing the appeal of ‘safety in numbers’ for the terns. However, launch them too soon and the rafts will be taken over entirely by black-backed gulls before the terns arrive, launch them too late and the gulls will already have nested elsewhere. Time will tell…

Incidentally, the name of this blog comes from a line in a poem inspired by terns:

And here they are, those white birds with quick wings,
Sweeping over the waves, chattering and plunging,
Their thin beaks snapping, their hard eyes
Happy as little nails…

The flock thickens
Over the rolling, salt brightness.

Mary Oliver, Terns