Juvenile BLACK-THROATED DIVER in the West Midlands
Plate 1: Juvenile Black-throated Diver at Ryders Mere, West Midlands January 29th 2011. Photo: Chris Cook
Originally identified as a Great Northern Diver, this excellent photo shows the typical 'jizz' of Black-throated Diver including the characteristic rounded head/neck profile and relatively thin bill. Note also the amount of white behind the eye - Great Northern would show diffuse greyish markings in this area. The intricate upperpart scaling age the bird as a juvenile.
Plate 2: Juvenile Black-throated Diver at Ryders Mere, West Midlands January 29th 2011. Photo: Chris Cook
In this photo, the head does appear more bulbous and together with the steep forehead provides a more Great Northern like impression. This individual also shows conspicuous dusky markings on the neck which lead some observers to consider the possibility of it being a Pacific Diver. However, rather than being the distinctive and often quoted chinstrap, these markings are merely a 'ghosting' of the black throat that the bird will exhibit in summer plumage and fall within the range of plumage variability of Black-throated.
Plate 3: Juvenile Black-throated Diver at Ryders Mere, West Midlands January 29th 2011. Photo: Chris Cook
The conspicuous white panel on the rear flanks, typical of Black-thoated Diver is shown well in this photo. Note also how posture can affect the head shape. Compared with Plate 1, the forehead appears steeper due to the peaked forecrown.
