by Steve Westerman

Wharfedale Naturalists Society

WINTER must be a very difficult time if you are a kingfisher. Once the leaves are off the trees and the vegetation dies back your plumage is presumably even more conspicuous, making you more vulnerable to predators.

Kingfisher mortality rate is high throughout the year with, on average, something like 75 per cent of birds perishing. Many youngsters die while acquiring fishing skills or because they are naive with regard to the dangers of their world. For birds that successfully make it through to the winter there are new challenges. Some birds succumb to the cold – some die from a lack of food, brought about by the seasonal changes.

Kingfishers are specialist hunters – their diet is almost exclusively fish. They will sometimes take insects or amphibians, but it’s not clear whether this is more often by mistake than intention. In any event, it seems that it is only in small quantities. Their restricted diet must make them more susceptible to environmental changes than would be the case for omnivorous predators (such as the Grey Heron). Kingfishers need a ready supply of small fish (less than 4” long) – and this should be in relatively slow flowing, clear water with suitable perches above. When the level of the Wharfe rises, and the flow increases – as frequently happens – many of their usual fishing perches will suddenly be above fast flowing, deep, murky water.

Over a period of perhaps 15 or 20 minutes I watched the kingfisher shown in the photograph repeatedly diving for food. After a few attempts from one perch it moved a few yards along the river and tried again. As far as I could see, all of its attempts were unsuccessful. In cold weather fish are less active, and presumably more difficult to locate. Kingfishers will sometimes do ‘dummy’ dives, to disturb fish that may be hiding under cover. However, when targeting fish, they generally have a high success rate for their dives. Of course, this is important because each dive uses precious energy. I could imagine that this bird was getting desperate.

Over the next few days I looked for the kingfisher along its usual stretch of the river – but there was no sign. I wonder if it managed to find something to eat – or whether the conditions proved too difficult. Perhaps it decided to relocate. Netting studies have demonstrated that, in the UK, kingfishers usually don’t move very far, perhaps just a few miles. So maybe it will survive the winter and be back again next year. Let’s hope so.