Mysterious Sunbathing Herons

I have noted herons quite a few times in my posts. In particular, in 2009 I reported how I thought they were getting more bold and less afraid of boats passing. However, on Sunday when returning from a short trip through Milton Keynes and travelling north, I noticed behaviour by a couple of herons that was simply mystifying.

It has been pretty warm recently with official temperatures in the high twenties and temperatures measured on the boat in the low thirties. Passing through the area just north of Campbell Park, Milton Keynes, Maggie pointed out a cormorant drying its wings. Shortly afterwards, I looked over towards the towpath ahead and saw a heron with its wings in a very strange pose. I have seen herons using their wings to avoid the reflections when fishing but this bird was on the bank looking south towards the late afternoon sun with its wings extended forming a parabolic shape. It was as if it was trying to collect solar energy and warm its wings. The only problem is the weather was hot!

First "Sunbathing" Heron

Just to confirm the behaviour, just around the corner I passed another heron that was adopting the same unusual pose.

Second "Sunbathing" Heron 

It appears, from a web-search, that others have seen this behaviour in herons all over the world (Brazil, Africa and USA). It appears it may not be associated not with "sunbathing" or "wing drying", although these terms are used, but possibly cooling or thermo-regulation with some birds also seen to be gulping air.  (Not in this case). A similar image featuring a blue heron in Texas was published on a science blog a few years back and it provoked some interesting discussion about the reasons for the odd pose. Some have even termed it "bird yoga"

I suppose the pose could be for a mix of reasons, but whatever the reasons it is unusual and interesting to see with two birds relatively close to each other and on the same day.