Thursday, 9 May 2019

Magpie May

Not the best pictures I've ever taken (quickly taken through the kitchen window while rushing to work, making me late) but this is a great example of why over the last decade or so I've got to admire corvid intelligence so much.

This magpie is in the garden all the time, but recently has begun feeding from the seed feeder. With one leg on the wall, the other pulling the feeder near enough to feed, it happily munches through the seed. Many people would resent a magpie in the garden but I love them, And being an intelligent species I hope that next week I'll be posting images of it actually filling the feeder and doing a bit of housework. 

But look at the colours on that tail too. And the wing coverts. Many corvids with long tail feathers have this colouration in various degrees of intensity. Given this is breeding time the colours are intensified. What is interesting is we don't really see this blue, it is a polychromatic effect caused by light splitting within the feather structure. As individual cells of the feather are formed, they contain keratin which separates out in a number of strings, a bit like oil does on water. As they mature and then die this liquid dissipates and air spaces form in the void. Thus, when white light strikes a blue feather, the keratin pattern that remains causes red and yellow wavelengths to cancel each other out, while the blue wavelengths of light intensify and reflect back to the beholder’s eye. 

Earlier in the month I was staying at my parents house in the North East of England. In their garden is a huge holly tree. Which now that they are not as mobile as they were, sits in a garden that is reverting to wildlife in a magical way. Holly blue butterflies swarm around the tree, coal tits, greenfinch, blue tits, starlings and sparrows make their home in or around the garden. But what caught my eye this time was that a magpie pair have made a nest in the top of the tree. Nothing remarkable in that other than given all corvids are quite wary of man, nesting in a garden is a real treat. I struggled to get images of the birds entering the nest, but these will suffice as a record of nature taking over the homestead. 

The nest is just left of top dead centre in the above image, and here it is on zoom. Those holly leaves will give some protection from carrion crows I'll bet!!

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