View from our balcony at Rua do Bonjardim, resembling the state this country is in.
The 40.000 - 50.000 gulls that I'd guess are present in the
whole area around the harbour in fall, primarily lesser Black-backed - and
Yellow-legged Gulls, were obviously attracted by the fish that was available to
them. In Porto, Yellow-legged Gulls also eat garbage and there appeared to be a
small resident population of them nesting on the roofs around our apartment.
There were many colour-rings to be read in Porto. Most successful
locations were Leixoeis and Matosinhos beach.
Mortality: it appeared that many gulls get trapped in
fishing nets. This occurs offshore, when the birds are following fishing boats,
as well as in the harbour, where the birds get trapped in fishing nets that are laying
around on the docks. Some of these unfortunate birds only lose a leg, but many
of them probably drown. The number of birds that die this way remains unknown
to me, but I suspect there are many. Additionally a number of birds die on the
docks, when these are run over by speeding forklifters that transport the fish
from the boats to the market. I observed about 5-7 birds to die this way on
each of my visits to the docks.
'7TH', a British bird, got trapped in a fishing net on one of the docks and could later be released. I've started to suspect that especially ringed birds run a high risk of getting stuck in fishing nets...
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