Photo: white-throated dipper: found in hilly locations across the UK including Wales, Ireland, Cornwall, Scotland and the Lake District

 

Dippers don’t merely dip, they plunge, walk and even fly under water. Bill Naylor guides us around the life of this most characterful of British songbirds, which demands special conditions if kept in captivity

 

DIPPERS are the only aquatic passerines and our resident representative in Britain is the white-throated (Cinclus cinclus).

The name dipper, from its habit of bobbing up and down, didn’t appear in print until the 18th century and until then it was more commonly known as the water ouzel (ouzel being the Shakespearian name for blackbird).

It was also called water blackbird or even by the blackbird’s other name (celebrated in The Twelve Days of Christmas) of “colly” bird, meaning as dark as coal, even though the dipper isn’t at all. It is sometimes, more understandably, called water thrush: once classified with the thrushes, they are still considered to be closely related. But while dipper fledglings and juveniles are similar to those of thrush, the dumpy adult bird is more the shape of a wren at twice the size and with a similar song and nest.

Replicating wild habitat
Our native species is only found where there are swift-flowing, unpolluted streams or rivers with gravel bottoms that are well oxygenated, ensuring a supply of aquatic invertebrates. It needs a hilly location and, as expected, this means the species is common in Wales, Cornwall, the Lake District, Scotland and Ireland. You’ll never see this bird in the wild in flat, polluted regions.

An aviary for captive-bred birds will need to provide fast-moving circulating water that contains submerged gravel and half-submerged stones. Dippers are strong flyers, so a flight should be a minimum of 3m (10ft) long, with adequate foliage for shade.

Distinctive characteristics
The white-throated is brownish-black with a chestnut-brown head. The eyelids are covered with white feathers that produce a white flash as the bird blinks, which it does often. This is frequently accompanied by the cocking of tail and the obligatory dip.

This species has a wide distribution, with numerous subspecies found through Europe and Asia, varying slightly in plumage coloration. The British subspecies (C. c. gularis) has a distinctive large chestnut band below the white chest and there are also rare visits in the wild from another European subspecies.

In all dipper species, the sexes are identical, but males are larger and the plumage of both sexes darken with age. The dipper is well adapted to its habitat of fast-moving water. A thick nictitating membrane protects the eye and the lens is designed to compensate for the distortion of objects in water. Slit nostrils with flaps ensure watertight protection. Its blood also has a high haemoglobin content, which means it carries more oxygen than the blood of land birds, assisting it when submerged.

Over and under the water
As with cormorants and other water birds, dippers have an abundance of contour feathers and an extremely large preen gland. Handlers note dippers are often covered in fleas; the parasites living on the surface of the feathers to avoid the bird’s dense plumage. Dippers require this waterproofing and insulation when they dive into chilled water.

Frank Meaden believed the plumage of his dippers was inferior to wild ones. With their food provided for them, he reckoned, captive birds didn’t need to submerge as much – and consequently didn’t preen and maintain their soft dense plumage as much, either – as they would have in the wild.

A dipper’s legs are long and strong, like those of a babbler. Their toes are equipped with long sharp nails that can grip your fingers like a vice! The strong feet are used to clamp and grip on to stones when standing in fast-flowing streams or on the river bed. This not only prevents them from being swept away, but also stops them floating up to the surface, due to the buoyancy of their insulated plumage when submerged.

In the wild, the dipper keeps cool in summer by wading in water, where it forages by turning stones and other debris. There is a small hook on the end of its bill, which helps it to catch aquatic insects, such as caddisfly larvae. But they also take fish and fish eggs, and even hawk for aerial insects. Dragonflies and other large items are beaten against a rock. Frank Meaden fed his dippers fish, fresh-water shrimps and ox-heart strips.

Feeding underwater increases in winter when food on the surface is scarce. When submerged, the dipper will often forage face down, facing the current as the water skims off its shovel-shaped back. There was a theory that dippers don’t swim while submerged and are carried along by the water current, but this has been discredited. Their wings act as paddles and function in a similar way to those of puffins and other auks which effectively “fly” underwater. It’s no coincidence that both auks and dippers have a similar direct flight and less manoeuvrability in the air than other birds of comparable size.

Courtship, nesting & young
The dipper’s characteristic call is a penetrating whistle: “zirt-zirt-zirt”. This is also used by the female when she selects a mate that has performed a satisfactory courtship display. However, the male also has a pleasant song with short penetrating notes. His display is very similar to that of the European wren: he holds his head vertically to expose his white bib and quivers his wings while singing. Chase-flying often ensues prior to nest building.

The large globular nest has a side entrance and a thick outer layer of moss cladding, with a more robust blackbird-type nest constructed of grass and leaves inside. All species of dipper nest close to water – often under bridges, but also located beneath ledges and outcrops of stones or woven into tree roots in a river bank.

The nests are frequently splashed by water and many must be lost when rains cause mountain streams and rivers to rise. Dippers will nest adjacent to and even behind waterfalls where the only access is flying through the torrent of water. Records show some sites have been used by successive generations of dippers for as long as 30 years – and in one case 123 years!

Nest-boxes are readily used in the wild and in captivity, provided they can accommodate the large amount of nesting material. In captivity, more than one nest-box should be provided – two or more nests are often built in the wild before a family home is selected.

Three to six white eggs are incubated by the hen for 16-17 days. On occasion, the male is known to mate with two or more females and assist in rearing young. The nestlings are fed on a variety of insect life.

Dippers regurgitate indigestible items later as pellets. Usually, birds that regurgitate pellets don’t produce them
as nestlings in the early stages of their growth, so the parents only feed soft-bodied livefood during this stage. An article in Avicultural Magazine (1971.171. 173) stated that nestling dippers were reared on scalded mealworms.

Young dippers, if disturbed prior to being able to fly but already feathered up, will dive into the water and make their escape by swimming to a bank. They leave the nest at three weeks old and are dependent on the parents for three more weeks before dispersing to find new territories.

Bill Naylor has enjoyed a 40-year career in ornithology and aviculture.

 

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