Thursday, February 25, 2016

Long-tailed Tit subspecies in the Iberian Peninsula

There are two Long-tailed Tit (Aegithalos caudatus) subspecies in the Iberian Peninsula: A.c.taiti and A.c.irbii. The first occurs in central, North and Western Spain and Southern France, while the latter ocurs in Central and Eastern Spain (including most of Portugal). Iberian subspecies distribution is not fully studied, at least as long as I have been able to find in the literature, and some hybridization areas may occur.

Pinkish colours are restricted to undertail coverts and belly,
with rather uniform grey on upperparts. Andalusia, South Spain,
December. A.c.irbii.
A.c.irbii to the left, A.c.taiti to the right.
Check how darker is irbii on cheeks, and how the black stripe
almost reaches bill base.
Apart from the local, sedentary subspecies, there's no information of any foreig retrap in Catalunya (source: www.sioc.cat), neither in the whole Spanish ringing scheme (source: www.anillamientoseo.org). There's only the recovery of a Long-tailed Tit ringed in Spain and recovered in France, but no detailed information. The most likely scenario is that it will be a bird ringed close to the French border and recovered on the other side (?). No other references of foreign birds/subspecies in Spain have been found; and actually, apart from the striking White-headed Long-tailed Tit subspecies (A.c.caudatus), subspecies identification can be very tricky outside of the known distribution range.

 On January I trapped a very striking Long-tailed Tit that attracted my attention since I saw it for first time. I have trapped quite a lot of local birds around Catalunya, and I had never seen any individual similar: very clean white underparts and cheeks and extensive white patch in crown and forehead. In the same net I was lucky enough to catch a local individual, retrap, that was very useful to compare.

The "whitish" bird above, the local individual below.
And that is what happened when I put them together...
  A.c.caudatus can be quickly ruled out on plumage features, but what about europaeus?
Checking pictures during the breeding season taken in the breeding range of europaeus, all individuals fit with the features shown by the bird I trapped: extensive white crown, wide white forehead, whitish ("clean") cheeks and underparts...

The presumed europaeus (left) had appearently a stronger bill
than a normal taiti; although I couldn't take proper measurements,
it's so small anyway!
A.c.europaeus, picture by Emil Lundahl taken in Falsterbo
peninsula, Sweden. Note the very clean white underparts,
as the extensive white on crown and forehead and clean cheeks.
A.c.europaeus, picture by Emil Lundahl taken in Falsterbo
peninsula, Sweden. Note the clean underparts and very clean,
'open-faced'.

Looking to local breeders in other places in Catalunya, especially breeding birds in the Pyrenees, there're no obvious differences with breeding individuals in other places.

Local individual trapped in central Catalonia, age EURING 6
(because it was a retrap from 2013). A.c.taiti.
Wear was for sure not the cause of the whitish plumage, as worn
birds turn to be greyer overall. Breeding individual in central
Catalonia, June. A.c.taiti.
Local breeder in Pyrenees, ringed in July and recaught in
winter. Plumage features fit will all other breeders I have
seen in Catalunya. A.c.taiti.
Despite all of this, only DNA analyses could confirm for sure the subspecies identification... but in the meanwhile, keep looking at the Long-tailed Tits!

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