Bittern in breeding condition? (1 Viewer)

[Brett Richards]

In the first attached image, photographed at Thornwick Pool, Flamborough, on 25 April 2021, the bird shows a swollen yellow band from above the eye to the bill, and the gape line is similarly slightly swollen. The bird in the second image, photographed at the same spot on 15 February shows no indications of such features. Are these swollen areas indicative of a bird in breeding condition, or is it just down to individual variation? Could they be the same bird?

Brett

 

[jurek]

I am not an expert, but I read that breeding Bittern should show sky-blue, not yellow lores.
See:

(PDF) Geographical variation, sex and age in Great Bittern Botaurus stellaris using coloration and morphometrics

PDF | Biometrics, plumage and bare-part colour of 87 Great Bitterns Botaurus stellaris from the UK, France, Italy, Poland and Belarus, of known sex... | Find, read and cite all the research you need on ResearchGate

www.researchgate.net

 

[Brett Richards]

I am not an expert, but I read that breeding Bittern should show sky-blue, not yellow lores.
See:

(PDF) Geographical variation, sex and age in Great Bittern Botaurus stellaris using coloration and morphometrics

PDF | Biometrics, plumage and bare-part colour of 87 Great Bitterns Botaurus stellaris from the UK, France, Italy, Poland and Belarus, of known sex... | Find, read and cite all the research you need on ResearchGate

www.researchgate.net

I wouldn't describe the yellow bands as the lores, rather as supra-loral & sub-loral stripes. Strange that nothing like this is mentioned in the paper you referenced. I would describe the lores on the first bird (the one with the yellow bands) as greyish (female?) and on the second bird as bluish-grey, although at that time of year (15 February) both sexes should show greyish-olive (more or less brownish-tinged) or entirely geyish lores according to the paper.

Brett

 

[johnallcock]

I think you may have two individuals. The bird in the second photo appears to have a darker (blackish) crown, more clearly defined pale stripe above the lores and less heavily marked sides to the breast. Possibly also a longer bill but that's hard to judge.
Whether the yellow in the loral area is individual variation, variation by age/sex, or related to breeding condition, I don't know.