A SMALL dark object swirls on the surface of the pool by the edge of the River Devon.

I am momentarily confused as it looks like the size of a duckling or moorhen chick, but it is too early in the season for it to be a baby waterfowl.

I slowly swing the binoculars up to my eyes, quickly revealing that it is, in fact, a dipper, a songbird about the size of a small thrush that actually swims.

Although at home in the river, the dipper is certainly not an accomplished surface swimmer with its lack of webbed feet making its movements somewhat erratic.

Then it dives underwater before reappearing a few seconds later to alight upon a large midstream boulder, its vivid white breast conspicuous as it bobs up and down.

Or, as the Scottish poet Norman MacCaig, noted: “He stands there, bobbing and bobbing as though the water’s applauding him.”

Usually, a dipper walks or plops into the water from the river edge or a rock before disappearing where it uses its wings to exert downward thrust to counteract its natural buoyancy, enabling it to forage for such small creatures along the bottom.

I have noticed that the dippers on the River Devon tend to swim on the surface like a duck only in winter and when it is very cold.

I’m not sure why this should be the case, but it could possibly be due to aquatic invertebrates moving into deeper water during such conditions, meaning the dippers themselves have to venture further out into the river before diving down to reach them.

Dippers are one of our earliest breeders, with eggs usually laid by early April.

It is thought that they nest early so that the hatching of chicks and development of fledglings coincides with a peak in abundance of aquatic invertebrates in the river in May and June.

The abundance of aquatic invertebrates such as mayflies and stoneflies are dependent upon water cleanliness and the presence of dippers is a sure sign that all is well with the river.