Birding Opportunity (Initial Sighting)

Sighting Ref :

IB53948

Sighting Date :

18 Feb 13

Common Name :

Birding Opportunity

Scientific Name :

Initial Sighting

Location :

Donaghmede

County :

Dublin

Number Seen :

Principal Observer(s) :

Victor Caschera Not Specified

Reported By :

Not Specified

Comments :

10.55. Possible Gray-bellied Brant. Donahies Community School. Between them I think these videograbs are quite informative on the key features to look out for when trying to nail this bird (strong but incomplete collar, mid-grey/brown but brant like pattern to "bib" on underparts, back colour only slightly darker than hrota, and extent of dark between the legs) Clearly none of these features can rule out an F1 hrota x nigricans hybrid, but whilst these do exist (I saw a hybrid pair with young in Iceland last year for example) they are widely acknowledged to be v unusual. It seems much more likely that a bird like this arrives from the WCHA/Melville and Prince Patrick/Grey-belly population (this population is effectively a cline from hrota to nigricans equivalent to eg. kumliens gull being a stable cline between thayer's and iceland gulls). I am 99% sure this is the same bird I saw in Donaghmede (that time in the Ayrfield estate) last year. The brent in this area are highly mobile and so this bird could prove difficult to track down. The best chance will come early(ish) in the morning when the majority of birds gather in one of the Donaghmede parks (Donaghmede Park/Grangemore Park/Donaghies school pitches) before dispersing more widely during the day. However this is far from a hard and fast rule. The areas used by different individuals can also change considerably so it may be that this bird goes off my radar from time to time.Millbrook Avenue. c. 900 hrota. Matt Silk. Description: Size/structure = as hrota (reckon its probably male as its on the beefy side) Bare part colouration = as hrota Upperparts = within variation of hrota but on the darker side.... COLLAR - very strong white collar, only partially broken at front and the ends clearly visible as "fat white blobs" when viewed directly from behind. Lowest white section of the collar particularly strongly marked. Collar more similar to nigricans in many ways apart from not being complete. UNDERPARTS - most like a washed out nigricans. The effect of the underpart "panel being split into two triangles is very similar, with pale flanks contrasting with the front/lower section. In this beast this was slightly darker than even the darkest light bellies it was with. NB. colour alone is not enought to pick it out, the pattern is important.... Dark pales bellies typically have the dark in a "block" rather than the nigricans like "triangle" BELLY - area between/immediately ventral to the legs slightly dusky mid-grey (between even the most strongly marked hrota and the pattern shown by nigricans/bernicla where there is extensive colouration It is surprisingly hard to pick out (and this varies depending on the light) but the combination of those three key features nails it as not being a light-belly. Whether and F1 hybrid or grey-belly is unclear (balance of probability should favour the latter...) There are 2/3 further birds in north Dublin that I strongly suspect have some Brant/Grey-Belly genes in them ie. may well be from Melville Island or have parents from there but that can wait until another time. Bear in mind, according to Sean Boyd many grey-bellies in Puget Sound in winter may not be distinguishable with any confidence from East Coast High Arctic (hrota) birds and this idea is supported by the appearance of birds on Melville. Similarly at the other end of the range on Prince Patrick Island many birds are v v brant like.... Its a minefield!

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