Tuesday 11 December 2012

The female Tawny Owl has found a new branch to spend the day on, in the beech tree behind their nest tree. She is easily visible here, and when I visited she was awake and shifting around to get herself comfortable.

Her mate remains in his usual place on the top of the broken trunk of the nest tree.

The Great Crested Grebes that I photographed displaying to each other on Sunday have got slightly carried away by their enthusiasm, and were waving leaves at each other.

This is something that they would normally do only when seriously intending to nest. But they were in shallow water and could pick up leaves easily, and a gesture of affection is always worth while. The offerings that birds give their mates raise the question of whether birds can actually think in terms of symbols. When a grebe waves nesting materials at his mate, does he actually consider that this represents nesting activity? When a Robin offers food to his mate, is he aware that this symbolises his willingness to feed her when she is sitting on their eggs? But this is probably an overestimation of their capacity for thought. These rituals are hard wired into their behaviour.

The ground is frozen and the Blackbirds can't pull out worms, though they can still find small creatures in the leaf litter under the bushes. They are noticeably hungrier, and even the migrant Blackbirds, which are completely wild and not accustomed to being fed, will run to take a piece of food thrown for them. Here one of the resident birds near the Peter Pan statue takes a large piece of cheese ...

... while her mate stares eagerly from a bush waiting for his turn.

Returning to the subject of birds' binocular vision, note that this is a straight-on look with both eyes, and the tip of the bird's beak is exactly between its eyes as it stares straight at the camera. This view would be the last thing a worm sees before the pitiless beak comes down to grab it.


  1. Good evening Ralph
    Another great post today thank you , many times during the day i want to stop as i pass by the park but the birds won't pay my bills so i continue knowing that i will have the pleasure of reading your blog about the days events .
    Main reason for the comment is to let you know i saw the peraguine on the metropol hotel today which is the first time since you informed me about them there and i check everyday !!

    1. It is a terribly long way up to the top of that tower, isn't it? I don't suppose you carry your longest lens about with you when working. One of these days I will run into someone with a digiscope setup and herd them up to the Metropole Hotel -- and probably find that the Peregrines aren't there.

  2. Apologies if you've covered this before but I've been intrigued several times this year by certain Cormorant behaviour. They'd be perched with other birds, usually gulls, on those posts sticking out of the water but the Cormorant would have its wings outstretched and hold that position for some time. I've not seen any of the other birds do that - a brief shake of the wings and then settle down - but the Cormorant sits there holding its wings out. Drying out? Cooling down? Display? Some other reason? I'd be interested to hear if you know what's going on here. Thanks.

    1. Cormorants hold their wings outstretched to dry them. It's commonly said that their feathers aren't waterproof, but that is an oversimplification. The inner layer of their feathers is waterproof to keep them warm and dry. The outer layers are wettable, and this is useful because the water decreases buoyancy when the bird dives. If the outer layers trapped air in them, the Cormorant would have to struggle to stay submerged, like a diving duck which expends almost as much energy swimming downwards as it does to move along.

      But it does mean that when a Cormorant surfaces, it has to hold out its wings to dry the outer layer of its feathers. It's an instinctive behaviour, and sometimes you see Cormorants holding out their wings while it's raining.

      There is more explanation on this brief page. Links don't work in the comments so you will have to copy this URL and put it into your browser.

      Wettable feathers are not the only way to decrease buoyancy. Grebes have a better arrangement: they flatten their feathers before diving. If you see a Great Crested Grebe on the surface with its shoulders more or less submerged, that is a sign that its feathers are flat and it's in diving trim, and usually it will dive in seconds. If it intends to stay on the surface, it relaxes its feathers and spreads out, and seems to be floating higher in the water.

      This is even more obvious with a Little Grebe, which can apparently double in volume when it's on the surface. A Little Grebe clenches its feathers down a fraction of a second before it dives. You will notice this if you watch one carefully.

  3. Fascinating. I'll watch a litle more closely next time now I know the reason. Due to the link I'm now also aware of a sun-bathing bird! Many thanks.