NATURE: Kingfisher’s head and beak inspired designs for Japanese bullet trains
The kingfisher is an iconic bird, unmistakable with its brilliant blue and orange colouring.
It is a favourite subject for many wildlife photographers and artists, frequently featuring on calendars and prints.
Kingfishers breed over much of Europe, their range extending as far north as southern parts of Scandinavia.
After the breeding season, they disperse, some relocating to the coast. North eastern populations are migratory but generally winter within their breeding range.
Individuals from these populations are rare vagrants to Shetland. Recorded by Andy Johnson at Clickimin Loch this week, this kingfisher re-appeared in the same area a few days later.
Although these birds have such dazzling, colourful plumage, they can be difficult to see when perched on a branch above the water. Where bushes overhang, the kingfisher can stay concealed until it dives to catch a fish.
The main prey is small freshwater fish like minnows or sticklebacks. As the bird plunges into the water, its eyes are protected by transparent eyelids.
When a fish is caught, it is taken back to the perch and stunned by being repeatedly hit against the branch before it is swallowed head first.
A kingfisher must eat the equivalent of its own body weight in fish each day. When they fly, the flight is straight, rapid and low over the water.
The dagger-like bill comprises about a third of the body length of 17-19.5cm. The sexes are alike, except that the bill of the male is all black whilst the female has orange-red on the lower mandible.
The shape of the beak allows the kingfisher to dive into pools soundlessly, without alerting the fish of its presence. Engineers used this feature, copying the shape of the kingfisher’s head and beak, when designing the high-speed bullet trains in Japan.
This allowed these fast-travelling trains to enter tunnels without creating a sonic boom.
In the UK, kingfishers are widely distributed along rivers and lakes, but they are absent from northern Scotland. It is estimated by the British Trust for Ornithology that the UK population is around 3,850 pairs.
Populations are vulnerable to severe winter weather and the degradation of habitats through pollution or development. It is estimated that half of the fledglings do not survive beyond a few weeks.
The average lifespan of a kingfisher is only two years.
The contrasting copper-orange and blue plumage of the kingfisher creates a jewel-like effect, but these colours are not all achieved by coloured feathers. The bright orange breast feathers contain pigment, but the vivid blue feathers are actually brown.
The colours we see are an example of structural colouration. The colour is created in the barbs, tiny branches which grow out sideways from the main feather shaft. Research has shown that these barbs contain spongy micro-structures with holes of different sizes. This internal structure reflects light in different ways, which we perceive as bright blue colours.
This adds to the magic of a kingfisher. Sometimes the colours look dark blue, turquoise or even green, depending on how the light is being reflected.
Anne Ellison found a national rarity this week when she photographed a black-faced bunting at Njugal’s Water. This rare vagrant from Siberia later moved to the Brig o’ Fitch where it provided birders with some good views. This was the second black-faced bunting found this week in the UK, a bird which is rarely recorded in western Europe.
A first winter bird resembles a reed bunting but is a dull olive-grey with yellow-tinged upperparts and a pale moustache. The “black-faced” part of the common name refers to the grey head and black face of the adult male.
In addition to the kingfisher, local rarities included a small influx of long-tailed tits in Whalsay, Yell and Unst, a short-toed lark at Quendale, a ring-necked duck in North Roe, great egrets seen in Yell, Unst and North Roe, an olive-backed pipit in Sandwick, firecrests at Unst and Virkie and a taiga bean goose at Clickimin.
The taiga bean goose is a rare migrant which breeds in the taiga zone in Scandinavia and Siberia.
Bean geese are closely related to pink-footed geese but have darker plumage, orange legs and orange on the bill.
The taiga bean goose is recognised as a separate species, but individuals can be difficult to identify from tundra bean geese.
The taiga bean goose has a proportionately longer neck and the bill has a straight lower edge and is mainly orange.
By Joyce JM Garden