Monday, 17 March 2014

Week 44: Snow Bunting ('Plectrophenax nivalis')

The Snow Bunting was @SpeciesofUK from 23rd December 2013 to 5th January 2014.

Snow buntings are small birds that breed mainly in the Arctic and migrate south in the winter.[1]

Snow Bunting
[Flickr Creative Commons © foxypar4]

In the UK, we have a large wintering population of snow buntings and we are also lucky enough to have a small summer breeding population, in the Cairngorms of Scotland.[2] Snow buntings have been described as “possibly the most romantic and elusive bird in the British Isles.”[3]

Snow buntings are Arctic specialists.

The breeding range of the snow bunting circles the whole globe, above the Arctic Circle.[4] Snow buntings have feathered feet to protect them in this harsh environment.[5]

Snow Bunting
[Wikimedia Commons © Corentin250292]

Generally, snow buntings only travel south of the Arctic in winter, but the UK is rather special as we have a tiny summer breeding population of sixty to seventy pairs on the high plateau of the Cairngorms.[6]

The Cairngorm snow buntings can be seen quite easily from the funicular car park when the snow extends down that far.[7]

Snow Bunting near the Cairngorm Car Park
[Flickr Creative Commons © indyhoose]

In the winter, the UK snow bunting population becomes more numerous as it’s swelled with migrants in the north and right down the east coast as far as Kent.[8]

Snow Bunting Flock
[Flickr Creative Commons © úlfhams_víkingur]

Snow buntings are members of the longspur family.

The snow bunting looks like a finch or a bunting (hence its name) but is actually neither; it's from the closely related Calcariidae family, the 'longspurs.’[9]

Calcariidae contains six species in total. Most are found only in North America. Only the snow bunting and Lapland bunting are found in the UK[10]

Lapland Bunting
[Flickr Creative Commons © fveronesi1]

There are four subspecies of snow bunting: Plectrophenax nivalis nivalis, P. nivalis vlasowae, P. nivalis townsendi and P. nivalis insulae which is the one we get in the UK.[11]

A close relation of the snow bunting is McKay’s bunting, Plectrophenax hyperboreus, which has purer white plumage. In the Arctic the two species sometimes hybridise.[12]

McKay's Bunting
[Flickr Creative Commons © jomilo75]

Snow buntings have a striking ‘snowy’ plumage.

In their summer breeding plumage, male snow buntings have all-white heads and underparts with a black mantle, wing tips and bill.[13]

Male Snow Bunting in Breeding Plumage
[Flickr Creative Commons © Smudge 9000]
Male Snow Bunting in Breeding Plumage
[Flickr Creative Commons © brian.gratwicke]

Female snow buntings are more grey-black on their upperparts.[14]

Female Snow Bunting in Breeding Plumage
[Flickr Creative Commons © quinet]

In North America, the snow bunting is sometimes affectionately known as the 'snowflake.' This is thought to arise from the likeness a flock of snow buntings in flight has to a swirling flurry of snow.[15]

In the autumn and winter, snow bunting plumage turns somewhat ginger-coloured and is noticeably mottled.[16]

Winter Plumage
[Flickr Creative Commons © Kelly Colgan Azar]
Winter Plumage
[Flickr Creative Commons © talis qualis]

Interestingly, the snow bunting's change in plumage from winter to summer is not achieved through a moult. It's actually just a result of the coloured feather tips wearing down.[17]

Snow Bunting Plumage Variation
[Wikimedia Commons © Richard Crossley]

Juvenile snow buntings are distinguished from the adult by a greyer body and head, and a dark brownish-black tail and wings.[18]

Male snow buntings sing with a rapid, musical trilling or warbling. The calls include a soft rattle, a loud ‘tsweet’, a sharp ‘chi-tik’, and a mournful ‘teu’.[19] You can here some of these sounds on the BBC’s Tweet of the Day.

Snow buntings migrate to Arctic sites to breed.

The male snow bunting migrates first. It returns to its freezing Arctic breeding grounds (or our own Cairngorms) in March or April to establish a territory.[20] The breeding habitat is tundra, treeless moors or bare mountains.[21]

Male Snow Bunting at Iceland Breeding Ground
[Flickr Creative Commons © t_buchtele]

The female snow bunting arrives four to six weeks later. To attract her, the male displays by singing, flying up high and then gliding down.[22]

Snow buntings nest in June. The nest is a thick cup of moss, grass, fur and feathers and is built by the female deep in a cavity in rock or within a man-made site.[23]

The female snow bunting incubates two to eight eggs for between ten to fifteen days. She's sometimes fed by the male so she can stay on the eggs to warm them.[24]

Snow Bunting Eggs
[Wikimedia Commons © Didier Descouens]

The snow bunting chicks are cared for by both parents, who split the brood between them. The chicks leave the nest after a couple of weeks.[25]

Snow buntings in Arctic regions raise one brood per year. In more southerly parts of their range like Scotland they sometimes raise two broods.[26]

Young snow buntings are fed mainly on invertebrates, including crustaceans in coastal areas. Adults diversify into seeds, grains, buds and young leaves.[27] They can form dense foraging flocks in winter.[28]

Foraging Snow Bunting
[Flickr Creative Commons © Langham Birder]

Snow Bunting Winter Flock
[Flickr Creative Commons © Laurel Parshall]

Strange but true…

Snow buntings are one of only three birds to have ever been sighted at the North Pole. The other two are both seabirds - fulmars and kittiwakes.[29]


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