Wednesday, 27 April 2016

Incubating crow

The finished Carrion Crows nests are very obvious atop the still bare trees. There are several breeding territories I cross on my way to work. Some of these seem to have used the same nest they built last year, others have built another one nearby, the older one still standing strong. If you are lucky you can get a glimpse of the incubating female's head or tail sticking out of the nest. The top shot, I took earlier today, shows that one of the campus pair have decorated their nest with white packaging material. Their nest, on a not very tall alder, is very visible.
Only female crows get brood patches during the nesting season: two bare and highly vascularised areas on the chest, which are in direct contact with the eggs and make incubation more efficient. These patches are covered with the feathers surrounding them, which the female fluffs open before sitting on the eggs. The male doesn't get brood patches, and doesn't incubate. During this time, the male feeds the female, and sometimes stands guard near the nest, as this poor photo shows. The female's tail sticking out of the nest on the left and the male sitting on the right. During the breeding period, the male is very protective of the nest area, and these days I see them mobbing Herring Gulls and Sparrowhawks that come near the nest.

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