Like a Polar Bear?

Yes I know it's that male Grey Wagtail AGAIN but dear reader, bear with me – do you know the colour of the calamus, because I didn't, I do now – I think!

Bandits at 11 o'clock, looking for flying insects overhead

Scratch

Time for a 'spruce-up'

including the tail

wings

and certain feathers, note the upper half

and the 'white feather' is in fact 'black' for the half closest the skin

back to business

It is great to get those 'award winning' photographs of birds we all hope will be in our collection but a lot of the time 'birdwatching' is just that, the photography a bonus. So while birdwatching, having seen 'that' bird for me it isn't about dashing off to the next one but to spend as long as possible with the subject to watch and study. I'll not bore you that lecture suffice to say, spending time with the Gret Wagtail(s) has been interesting and here re some images of the male having a clean up. From what I can see from some of these photos, the camulus on some of the feathers appear to be black(ish). It may be a well-known fact, but I had no idea. So while on the outside their white and yellow feathers and colour brightens the dullest days, underneath they are black, not unlike a polar bear whose skin is black! (I did wonder if living by running water if it was part of a strategy to keep warm).

Postscript, I am not sure this black part of the feather is actually 'the camulus', I may have may physiology and description incorrect so I would appreciate any comments or input.