A fair walk through the middle of Cliffe to the viewpoint at Flamingo was enjoyable for both Monty and myself at lunchtime, which was followed by a trip up to Birkbeck for a lecture on the wonders of the urban flora to feed the mind, to make another great day!
Common Gulls. On the bridge "over the Kwai", there were two Common Gulls,
Larus canus, and two black-headed gulls,
Chroicocephalus ridibundus. The two Common Gulls were nicely showing the bright white on the trailing edge of the wings, and the white tertial crescent, as well as the white mirror segments on the black wingtips.
The Common Gull to the right has a darker head, and less clear white spotting on the black wing tips. If it might be possible to persuade myself that there are dark marks on the wings themselves, then perhaps it could be a second year winter bird?
Black-Headed Gulls. The settled bird of the two Black-Headed Gulls here is turning dark on the head as it develops its breeding plumage, nicely showing the white eyelids more visible to the rear of the eye. The flying bird, about to land and decelerating sharply, does not appear to be so well advanced, but does show the wing patterns quite well, the dark "shadow" on the underside, the black-tipped primaries, the bright white triangle and front edge to the wings. There is also a dark mark at the front of the upper wing that might indicate a second winter bird as opposed to an adult bird.
And these other two birds seems to be mutually displaying to the other. According to BWP this could perhaps be "The Forward Posture", bird flat with spread scapulars, neck kinked and head held forward (although difficult to tell if the tail is flattened), generally a symbol of aggression often alternately shown by the two opponents, more commonly on the water (e.g. swimming towards opponent) than on land. A web source from a Dutch "larophile" says that it may also be part of courtship if the birds are parallel to each other, which doesn't seem to be the case here. This display itself may therefore be nothing to do with the season!
In his book The Animal in Its World, Niko Tinbergen characterizes this type of behavior as a ‘spacing-out’ display or ‘threat’ display, directed at opponents with the aim to move them away or to stop their advance.
The last picture also seems to involve mutual ritualistic postures, with spread scapulars retained, a little more like "The Upright Posture" or "The Oblique Posture", although I can't identify it exactly. One thing I can't sort out is that it doesn't look aggressive, and the birds are close together in this last shot.
However that may be, I also think that the birds' beaks are losing their red colour and becoming darker, almost black at a distance. In addition at least one of the bird's head is beginning to darken. Spring, I think, is still on the way!
Urban flora lecture. The wall bedstraw,
Galium parisiense, was found in a front garden just by Gloucester Road tube station, and is a rare plant of poor ground and urban as well as rural areas.
