by Steve Westerman

AUTUMN is upon us. All along the river, willow leaves are dropping onto the surface and being carried downstream. With the change in season, dippers (Cinclus cinclus) seem to be finding their way back to the town stretch of the Wharfe.

As I mentioned in a previous Nature Notes, through the breeding season, they haven’t been as prevalent as usual. Dippers usually nest along the banks of this section of the river, tending to use the same locations year on year. I think changes to the river bed, caused by the flood, and loss of vegetation on the river banks, made a couple of nest sites less secure. So, the dippers moved. Now, perhaps with the pressure of juveniles looking for territories, perhaps because the river environment is quieter, they seem to be returning.

Mainly darkish brown in colour, with a white ‘bib’ (see photograph), dippers may not be the most aesthetically captivating of our river birds. However, closer inspection reveals more subtle details and tones to their plumage. They also exhibit fascinating and unusual characteristics. These energetic little birds feed on a variety of small aquatic animals, particularly insect nymphs and larvae, but also small quantities of fish eggs and fry. They search for food along the riverbed, often in shallow, fairly fast-flowing sections, by dipping their head below the surface. However, if the depth of water requires it, they are not averse to walking or diving under the surface, and swimming or walking along the bottom. They are the only passerine to do this. Their diet makes dippers particularly sensitive to variations in water quality. If small invertebrates aren’t well supported by the river environment then dippers will be scarce or absent.

In the water dippers can be difficult to spot. Their colouring provides good camouflage amongst the speckled reflections of light on the surface. However, at regular intervals they will stand on a rock – usually in the stream but sometimes at the side of the river – and engage in a characteristic bobbing motion. Often, dippers can be seen in flight – travelling up and down the river. Listen for an in-flight call that is a somewhat harsher than the clear ‘peep’ of the kingfisher - but look for a similar low and straight trajectory over the water. Not the flash of blue of the kingfisher – but a bird that is just as unique.