Saturday, 21 January 2017

Spain 14: Bluethroat

One of the tiny gems of the European avifauna is the Bluethroat Luscinia svecica. They have a vast range, with the nominate subspecies breeding across the Old World Arctic tundra and even extending (just) into Northern Alaska. To the south other subspecies can be found in the breeding season from Spain across to western China and Southern Tibet. Outside the breeding season they winter from North Africa to India and Thailand. The Alaskan birds winter somewhere in Asia, but where is not known exactly.

A close relative of the Nightingale, Bluethroats share their relatives’ secretive habits and fondness for dense cover, although males are rather more colourful. Males have the blue throat that gives the bird its name, with in most subspecies a spot in the centre of the throat that is either red (in the northern, nominate subspecies) or white (most southern subspecies). In some forms there is no spot of either colour, at least visible to humans. As birds can see ultraviolet colours there also appears to be variance in UV reflectance that is obvious to other Bluethroats but undetectable by humans.

In the breeding season northern Bluethroats inhabit arctic tundra with dense bushes. Further south they use a variety of habitats but always with dense cover, often close to water. They will use human modified or created habitats sometimes – in Germany they are known to use crop fields sometimes – and this may be responsible for a marked increase in the western European population in recent years. In the winter they often frequent reed beds, which is where we found them on the Ebro Delta. In Spain the resident subspecies is a high mountain bird, breeding above 1700m on gentle slopes close to water with a dense cover of Cytisus and Erica.

Bluethroats are mainly insectivorous, but in the winter they will also take some seeds and fruit as well. Insects and spiders are gleaned from foliage, sorted from leaf litter, or sometimes caught on the wing. We sighted ours on the Ebro delta darting out from reedbeds onto the path at dawn and dusk looking for insects on the ground.

White-spotted Bluethroat singing:

In the breeding season males obtain territories soon after returning from winter quarters between April and July by singing either from perches or in song flights. Females lack the blue throat and construct a typical cup shaped nest lined with animal hair in dense cover. Clutch size is between 4 and 7 eggs and incubation is around 13 days. Young fledge after 13 or 14 days.

As a species, Bluethroats are listed as Least Concern and in fact may be increasing in numbers in parts of its range. Some subspecies may be more localised and may therefore be at more risk of habitat destruction. In the UK Bluethroats have bred but are almost entirely seen as vagrants during migration. 

(image from wikipedia)

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