by Steve Westerman

Wharfedale Naturalists Society

IN my last Nature Notes, at the beginning of February, I argued for the value to wildlife of having some undisturbed areas along the banks of the river Wharfe as it flows down to Ilkley, and on to Ben Rhydding. This month I thought I would continue to focus on the riverside environment by drawing attention to two of my favourite species of small songbirds that can be seen there. These birds are so small that they may ‘go under the radar’ if you are not looking carefully. With spring on the horizon, and covid restrictions due to be relaxed, the coming months could be a good time for this.

One of the smallest birds in the UK, the wren, seems to find the river banks a good place to live. They can be found in many places along this stretch of the Wharfe, sometimes in the trees that line the river, but more often they are darting around amongst the low vegetation along the banks. The wren’s Latin name (Troglodytes troglodytes) might suggest it lives in caves, but this isn’t really the case (see Jenny’s Nature Notes, 26th Dec. 2019, regarding nesting behaviours). Instead, it has been suggested that the name was inspired by the bird’s eagerness to explore nooks and crannies in rocky areas when looking for food. Along the river there are a few places where stone walls/mounds have been constructed to reinforce the river banks. Wrens can regularly be seen there, hopping between the stones, foraging in the crevices and amongst the mosses and lichens. They mainly feed on insects, but according to one source, if the opportunity presents, they have also been known to take small fish and tadpoles from shallow water. I think it would need to be a very small fish!

However, there is an even smaller bird that frequents the trees along the riverbanks. The goldcrest is the smallest British bird. To try to put this in perspective, an average robin, that we might think of as a relatively small bird, weighs something like 17 or 18 grams. A wren (at approx. 9 grams) is about half that, and a goldcrest (at approx. 5.5 grams) is not much more than half the weight of a wren and less than a third the weight of a robin. It weighs about the same as a 20 pence piece!