Published on 01 August 1911 in Letters

SIRS,–While it must be well known t h a t t h e ” fledgling “Guillemot (Uria troile) and Razorbill (Aha tarda) resemble in all essentials of their coloration t h e adults of their respective species when in summerplumage, extending even to t h e white stripe in front of t h e eye in t h e case of the Razorbill, it does n o t seem to have been recognized t h a t this plumage answers to t h e ” mesoptyle ” or second generation of down-plumage in other birds, e.g. t h e Tawny Owl. Y e t this, I believe, to be a fact, and accordingly I draw the attention thereto of the readers of BRITISH B I R D S , who are interested in all t h a t pertains to plumages and their changes. I a m n o t sure, yet, as to w h a t obtains in the case of the young Black Guillemot (Uria grylle) of the same age, which seems to resemble the adults in the winter dress, b u t the plumage of such young birds will, I believe, also prove to be of the ” mesoptyle ” generation. The young Little Auk, like the Guillemot and Razorbill, rasembles the adult in summer, a n d wears a ” mesoptyle ” plumage. The long woolly down of t h e Puffin, which differs so conspicuously from that of its congeners will prove, I believe,

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