Don’t dip on DIPPERS
This unique British bird is all too easy to overlook, so make sure you don’t miss out on seeing one, says Ian Parsons
AHIGH-PITCHED CALL FOLLOWED by a whirr of wings that blurred the shape of the bird as it flew low over the fast-flowing water, signalled the arrival of a Dipper. Landing on a rock mid-stream, the bird gave its characteristic bend at the knees, before it walked headlong into the torrent. All of this happened right in front of me as I stood on the pavement looking down at the East Lyn river in north Devon, where, after plunging off the high ground of Exmoor, the river meets the sea at the charming village of Lynmouth. Now, describing this as urban birding might be stretching it a bit – after all, the actual population of Lynmouth is only a few hundred people – but it was a late summer’s day, the road was busy with traffic, the pavements overflowing with tourists and the shops and cafés were doing a roaring trade. As far as Exmoor goes, this was urban! Despite all the noise and bustle going on around me, though, I was able to look down and watch a bird that is associated with the wild, unpopulated areas of Britain, proving that you can see great birds in the unlikeliest of places. The Dipper is indeed a symbol of wild places. It is also a bird that had often proved to be a bit of an enigma for me. To put it simply, I always used to ‘dip’ when it came to seeing Dippers! Many birders have bogey birds, and the Dipper used to be mine. I would go to the right places to see it, spend time waiting and watching, but for some reason I just wouldn’t see them. The frustration would then, of course, be compounded when another birder would gleefully inform me that they had seen one at the exact same spot the day before. There is no reason for this to happen, of course, it is just one of those things, and there is a solution. Perseverance, patience and a bit of research are the best way to overcome troublesome species. I asked other birdwatchers where they saw Dippers regularly and instead of having one site to visit, I got to know several.
I also researched their calls, and it was once I had learned that high-pitched flight call that I started to spot Dippers. Learning a bird’s song or call is a great help to finding that bird in the wild. Nowadays, I have no trouble finding this water-loving bird, even turning it up in unexpected places, as I have explained. Every time I see one, I enjoy it, for they really are special birds. No other passerine does what the Dipper does; its ability to dive into and swim and walk underneath the water makes it unique. Watching one walk head-first into a fast-flowing stream makes you realise what a specialist this bird is. It might look ‘ordinary’, sort of a dumpylooking thrush in appearance, but to do what it does takes some very clever adaptations, indeed. All flying birds have evolved a specialist bone construction that reduces their bodyweight yet maximises the strength of the skeleton. The bones have a honeycomb-like structure to them, making them basically hollow yet still very strong. All flying birds that is, other than the dipper family. Dippers are unique in that their bones are solid,
the density and weight of these bones making them a lot less buoyant, something that is important when your food can only be found under the water’s surface. The extra weight that Dippers have in comparison to other birds of a similar size may explain the frenetic whirring wings of the bird in flight – basically, it is having to put a lot of effort into getting that extra weight airborne. Their feet are very strong, with sharp claws that enable them to grip stones on the river bed. This, combined with proportionally long legs, helps them to resist the flow of water that is pushing against them. They are able to swim under water thanks to well-developed muscles in their wings, and the added strength from these muscles means that
The Dipper might look ‘ordinary’ but to do what it does takes some very clever adaptations indeed
they can use their wings like flippers, powering themselves through the current as they search for food. This search is also aided by a special adaptation to their eyes, which enables them to change the curvature of their lens and focus them under the water just as easily as when they are on land. Coupled with that, their ears have a flap of skin that can be tightened to ensure that they don’t get clogged with water when the bird submerges itself. This is a bird with ‘superpowers’, but the superpowers don’t stop there. As you would expect with a bird that spends much of its time submerged in moorland streams, protection against cold water is essential. The feathers on a Dipper are extremely dense, providing a thick layer of insulation that the bird regularly maintains using an enlarged preening gland. This ensures that their feathers stay as waterproof as possible. Dippers feed on aquatic invertebrates found in the river and stream beds. These are often hidden away, which means the bird has to hold its breath while it searches for them. They can hold their breath for as much as 30 seconds, a remarkably long time for a bird about the size of a Starling! To help them with this, they have another two adaptations. Firstly, their metabolic rate is much slower than a similarly-sized ground-dwelling
ÈCOURTSHIP FEEDING Adult Dippers indulge in a spot of courtship feeding
passerine. Secondly, their blood has a much greater capacity for holding oxygen than other similar-sized birds. What this means is that they don’t need to breathe as often as other birds and when they do take a breath, it lasts longer in their system than in other birds. Dippers are an excellent example of how evolution has honed a species to fill a particular niche. So where can you find these super-powered birds? Dippers are generally upland birds and are found in Scotland, Wales, northern England and south-west England. They love fast-flowing streams and rivers, with plenty of rocks and boulders to cause turbulence in the water, and also to act as perches. In winter, particularly a harsh one when watercourses higher up are prone to freezing, individual birds may move to more lowland habitats and even, on rare occasions, the coast. Make sure you enjoy the uniqueness of a Dipper soon.