In article , sacha
writes
in article , Malcolm at
wrote on 25/1/03 7:29 pm:


In article , sacha
writes
snip
And why our rookery is practically empty during parts
of the summer and then they all come home again......fascinating, really.

Once the young have left the nest, they are taken by their parents out
into the countryside looking for sources of food, staying as a family
group within a larger flock. The young are fed by their parents for
about six weeks or so. Once they have become independent, the parents
are free to come back to the rookery, which they usually do in
September-October, occasionally earlier, and from then on take a natural
interest in it (sometimes sporadic depending on the weather) until
nest-building starts in earnest in the early spring.

Thank you! We've seen signs of them starting to build now but I imagine
it's not serious construction work yet. The sparrows are certainly nest
building, though. I was fascinated to learn about the rooks that the reason
one sees them flying in pairs to pick up twigs but only one of them coming
back with a stick, is that the unencumbered one is the male riding 'shotgun'
to prevent 'his woman' from mating with another!

Who've you been listening to again? Ask your informant how they know
this and why it isn't the male having to carry the stick because the
female
doesn't want him chasing after other females?

As the sexes are identical in plumage, it's almost impossible to say
which is which when they're in flight, and pretty difficult even if you
see them side by side on the nest, when the male is very slightly the
larger. Of course, if you happen to see them copulate, then the male is
the one on top!

In fact, studies have shown that it is the male which usually does most
of the stick collecting while the female does more of the actual
building of the nest. And it is often normal for the female to stand
guard over the nest to stop neighbours stealing twigs from it while the
male is away twig collecting.

--
Malcolm