July 31, 2016
The River Severn is low and slow-paced, sliding between gravel braids and petty sand banks. Beef cattle and sheep graze the wide water meadows, mallards Anas platyrhynchos shelter in deep oxbows. The weather is kind with a gentle breeze of warm air under slate grey, rainless clouds that drift above the distant hills.
Field ornithologist, Tony Cross soon shatters the peace in this backwater at the heart of Wales; he dons waders and runs out a large-meshed net low across the river to trap goosanders Mergus merganser and another, much finer net, set higher and just downstream for common sandpipers Actitis hypoleucos and little ringed plovers Charadrius dubius. We head upstream and find 17 young goosanders alert on the river and a handful of common sandpipers walking the edge but no plovers. We work our way round and then nudge the goosander flock downstream; they soon skittle round the tight river bend towards the net. Some fly low but most paddle fast across the water on half-grown wings.
The catch when it comes is near perfect; of the 17 in the flock, we trap 10 with one doubling back and six making their escape downstream. The captured are quickly disentangled, and each is placed into a large cotton bag and processed on the river bank. Tony explains that this has been an extraordinary catch and much the highest in many years of trying; mist-netting is usually fruitless because water levels have to be just right and the birds normally don’t ‘stick’, so a good catch is a couple or so.
Each bird is calm in the hand and weighed, wing length measured and metal ring, with its unique alphanumeric code, closed on a leg with pliers. All are young birds reared this year, the males are larger than the females but impossible to sex at this age; the data do indicate that the small ones with short wings are probably from a separate brood that hatched a little later. Tony releases the fliers and puts the flightless back on the water at the river’s edge; all rip away downstream and out of sight.
The bird is an elegant design with a slender, streamlined head set off by a ginger Bart Simpson hairstyle and long, tipped bill. The absurd, aerodynamic lines atop a barrelled body driving two great, bright orange webbed feet enable these birds to run down fast fish and snatch them with snaking neck and serrated bill. Anglers are no competition, dynamite maybe.
Ringing and other studies have shown that nearly all adult male goosanders within Western Europe are no longer on breeding rivers such as the Severn; they departed in June, immediately after the young hatched, for a small number of sheltered fjords in northern Norway, here to undergo a complete moult for three months before dispersing home again.
Goosanders have been remarkably successful at colonising the UK since first breeding in the 1880s. The expansion of range and numbers has created a conflict with fishing interests and goosanders are now legally, and often illegally, controlled on many prized waterways.
Managing fish-eating birds and fish, raptors and gamebirds and any other top predator taking too big a slice of the owners’ cake is, more often than not, a fraught and intractable conflict. The answer is simple to those suffering the losses, but the killing or control that is advocated is entirely unjustified to many. So governments establish working groups of all with an interest and fund the science to provide the evidence to draw up management plans; these take years to formulate and when they finally appear are often perceived as inadequate by one group or other. The British countryside is too small, too used and too loved; since the mass trespass on Kinder Scout in 1932, the stage of festering antipathies.
Tony reckons that the common sandpipers will see the goosander net and rise over it and then not see the finer meshed net and run straight into it. This is exactly what happens and, through the morning, three common sandpipers (and a pair of goldfinches Carduelis carduelis) are held in one of the shelves that hang from the parallel cross strings. Each bird drops when it hits the net and the mesh effectively bags it. All are extracted with great skill and the sandpipers receive the same treatment except that bill length is also taken as another useful comparative biometric. A young sandpiper hatched this year is darker with chocolate edging to the upper wing feathers and the adults look lighter and more even in tone.
Common sandpipers, which breed on these upland rivers are declining in numbers and the reason is a mystery; the limited evidence suggests reduced survival in West African wintering grounds may be part of the story. The big picture is only constructed from lots of little pieces of data collected over many years. So, for many species in decline, working out what is going on is like looking at a jigsaw puzzle that is only just started. The problem is that by the time you have sufficient pieces on the board, the decline has often gone far too far.
Two young mink Neovison vison chase, duck and dive along a tangled stretch of river bank. Yellow wagtails Motacilla flava are as common as the pied wagtails Motacilla alba in the fields. Sand martins Riparia riparia nest in small numbers in the shallow river banks and hunt above the water. The last few years have been disastrous with unseasonal summer floods wiping out their nests. We look for a hobby’s Falco subbuteo nest in a huge oak but there is no sighting nor sign; finding the pair in the floodplain full of great oaks is needle in haystack hunting. The river at midday is silent; a single redshank Tringa totanus flutes in the distance. A sad echo from a previous age when breeding waders were as common as kites Milvus milvus today.
We make one final run upstream and somehow manage to move the single escapee back downstream and into the net. This makes 11 Severn goosanders!