The little Dutch moorhens I watched in Amsterdam are
about the most aggressive creatures I've ever seen, and
are at their worst during nesting season.
The moorhens ("meerkoetjes" in Dutch) are slate-gray waterbirds of about 50 cm (20 in) wingspan. They live on the surface of the
water — and it's good they do, because they'd
probably attack us if they walked on
land. As it is, they spend much of their time
harrassing each other.
Their mode of aggression is to run along the surface of the
water, menacing another of their kind by coming at it
from above and behind — behind because the other bird
wisely runs away. There is a characteristic sound of
flapping and splashing as the one chases the other just
out of the immediate area — usually no more than five or six meters away. Sometimes the other bird will simply bloop underwater, remain there for a few
moments, and come back up, apparently unbothered. Anyhow, he'll do it in return when he gets his
chance.
During nesting season, the moorhen will construct a
nest of available sticks and sticklike rubbish, upon
any flat area near the surface of the water. A tire,
the rim of a houseboat, or any such accommodation will
do. With a nest, the birds are even nastier than usual.
But it doesn't take a nest or a nesting season to make
a fight. You'll normally see the moorhens in groups on larger
canals,
floating about their business, when one of them will just
take some momentary inspiration, get up and
chase another away. Not really away; just to another
part of the same area of the canal.
