August 2009 – While waiting for the mushroom season to begin in earnest, the electric blue of a kingfisher always lifts the heart…
The coming weeks are the best time to see what must be our most colourful bird along our rivers and lakes. Even the most ignorant birdwatcher should have no difficultly recognising the small electric blue form streaking away low and fast across the water, for kingfishers are unmistakable with their bright metallic blue-green backs, orange breasts and red feet. At first glance the sexes appear identical, but when viewed close up, the female has a red lower mandible. In common with most birds, the young are drabber than their parents, only gaining the full iridescent plumage of their parents as they reach breeding age at a year old.
Unfortunately, despite their colouring, for much of the year kingfishers are surprisingly difficult to see, being small – they weigh barely an ounce and a half – and shy. They are much more visible in high summer, however, owing to their remarkable fecundity. In a good year each pair can rear three clutches of six or seven eggs, a feat which is only possible if backed by both adults hunting non-stop throughout the day.
While they are most often spotted fleeing from the human intruder, patient watchers can get a better glimpse by waiting quietly near favoured riverside vantage points. These are generally branches overhanging the water from which they dive into the water, eyes closed and bill open, to snatch small fish from the shallows.
Kingfishers are unusual – although far from unique – in nesting in tunnels which they build in suitable riverside banks. They excavate these using their powerful dagger-shaped beaks, mining 2 – 3 feet into the earth to lay six or seven almost spherical white eggs in a depression at the end. These are hatch after three weeks, after which each youngster needs 12 – 18 small fish daily. This means the parents need to catch prodigious numbers of minnows each day.
The chicks are fed in rotation, the order determined by the hungriest chick jostling its way to the front of the tunnel. With so many youngsters dining on such a rich diet, the nest chamber rapidly becomes deeply unhygienic. Fortunately the chicks fledge at four weeks, after which they rapidly have to learn the hard facts of life.
The huge demands for food mean pairs are extremely territorial, ferociously driving off any intruder on their stretch of water and even expelling their own young within a few days of fledging. As a result, mortality among youngsters is very high and their size and energy requirements mean they are particularly vulnerable to bad weather.
Many flee to the milder temperatures of estuaries and coasts in winter, but prolonged frost still kills many, leading to huge population fluctuations. In the past water bailiffs reasoned that salmon and trout fry must feature on the menu and persecuted them, while others were shot them to feed the Victorian passion for taxidermy or the hat trade. As a result the official population is the surprisingly vague 3,600 – 6,000 pairs. Fortunately, the recent spate of mild winters, coupled with the end of persecution, mean numbers seem to be on the increase.
Kingfishers are distributed across all of Britain, but are most common in lowland areas, along rivers, canals, lakes and gravel pits. Their two main requirements are suitable earth banks in which to dig a nest tunnel and plenty of shallow clear water where prey is easily spotted.