(Photo: Laurie Campbell)
Dippers might look a lot like the birds you see in your garden, but these little birds actually hunt underwater. Dippers are the only birds of their type (the passerines) which can do this, because of some very special adaptations:
• Dippers have lots more feathers on their bodies than other passerines, to keep them warm in the cold water.
• unlike some other diving birds, such as cormorants, Dippers don’t have to perch on a rock with their wings outstretched to dry off. Dippers have lots of oil on their feathers to keep them waterproof and when they emerge from the river the droplets just run off.
• they have relatively long legs for their size to help them wade in the water and sharp claws to help them grip stones in fast running water.
• their short, muscly wings work really well as flippers, so are great for diving down and swimming underwater.
• the muscles in their eyes are very strong, so they can change the shape of the soft lens in their eyes to make it possible to see very clearly underwater . We can’t do that - when we open our eyes under water it’s blurry.
• seeing clearly underwater is also helped by a third eye lid, which acts a bit like a windscreen wiper.
• Dippers have a flap in their nostrils which closes to keep water out when they dive – bet you wish you could do that too!
• when diving in deeper water, Dippers dig their claws into the bottom sediment to help push themselves along, making them look like they are running along the bottom.
• Dippers are able to carry more oxygen in their blood than other birds their size which helps them hold their breath for up to 30 seconds.
You can see Dippers as they search for food in fast flowing rivers and streams, feeding on the many animals found on the river bed, such as stonefly and mayfly nymphs, pictured below. The bird in the picture has creamy and light green caddis larvae in its bill, one of their favourite foods.
Stonefly (Photo: Ecology Adventure)
Mayfly (Photo: Ecology Adventure)
In the summer when river levels are lower, Dippers prefer to feed in shallow waters, as this uses up less energy than diving. They perch on rocks and feed at the edge of the water, but often will grip the rocks firmly and walk straight in until they are submerged. It’s in the winter months, when water levels are higher, that they have to spend more time diving for their food. They usually dive about five times per minute, but can stay under for up to 30 seconds if they want to.
Dippers nest early in the season, starting to get the nest ready as early as February. Both the male and the female work together on this, taking about two weeks to complete it. If they have the space, they build a football-sized ball of moss, leaves and grass, but many dippers have to make do with smaller nests squeezed into a crevice in a rock face or in the river bank, often by a waterfall, but sometimes behind it.
When perched on a rock, Dippers bob and dip up and down, which is why they got their name. It’s not clear why they do this, but one theory is that it makes it harder for animals under the rippling water to see them standing there. Another theory is that they are moving their heads rapidly to see through the light reflections on the water. Other birds which live by upland streams also bob up and down like this, including the Common Sandpiper, which is also found here in Harris.
A good place to see Dippers is on the Abhainn Mhòr (the Big River) at Amhuinnsuidhe, near the Castle, but you have to be patient, as they have to search for food up and down the river and need to spend about two thirds of the day feeding, so it can be hard to catch them at rest. Time spent by any of the fast flowing rivers and streams in Harris, at any time of the year, could reward you with a sighting of this great little character.
[Website includes the bird call from the British Library Sound Archive]
by Joan Cumming