Dear Wim and others,
I have often seen Silver Gulls trampling in very shallow water, wet
sand or sandy mud, so as to bring prey such as polychaete worms and
small bivalves to the surface. Sometimes there is a lot of running
about as one gull snatches prey from under another's feet.
Incidentally, the technique is also used by humans, typically small
boys seeking fishing-bait and Italian women seeking
bivalves(heart-cockles, pipis and venerids) for a meal.
Anthea Fleming
On 18/01/2011 8:33 PM, Vader Willem Jan Marinus wrote:
-----Ursprüngliche Nachricht-----
Von: im Auftrag von Alan Gillanders
Gesendet: Di 1/18/2011 5:36
Dear Alan and others,
The description is a little atypical, but I
suppose what your correspondent has seen, is gulls foot-trampling; here in
N. Norway (well, I write this from Germany, in fact) this is especially
common with Common Gulls, Larus canus, but I've seen Ring-billed gulls
doing this before, when on a vhiesit to the US. What the gulls achieve
with their trampling, is a liquefaction of the sediment, which causes
animals of the infauna--worms, mollusks, small crustaceans-- to come to
the surface where the gulls can easily pick them up. One can nicely
demonstrate this by foot-trampling lightly oneself. I have earlier written
more extensively in Birding-aus on the subject several years ago---have
also published, but in Norwegian--, and this may still be accessible in
the archives. If not, and there is interest, I can dig it up, and resend
the piece when I get homne two weeks from now.
Wim Vader, Tromsö Museum
9037Tromsö, Norway
Betreff: [Birding-Aus] Gull behaviour in eastern Florida
Greetings,
A friend in the states asked me about this behaviour, "Saw some
interesting behavior I've never seen before. There were several
ring-billed gulls, not our largest but fairly large birds, out in one of
the shallow lagoons. They were standing in less than an inch of water.
Several of them put their heads down, bills out in front in the water, and
walked back and forth plowing through the mud. They'd walk 6-8 feet (2
meters) stop, stand up, shake their heads, turn around, and walk back
again the same way. I've never seen gulls do that before. I suppose they
were trying to feed, but on what? Usually they eat larger stuff than
little mud bugs. Oh well, chalk another new thing up to birds that don't
read the books about them!." What would I know, I'm an upland rainforest
birder. If you have any ideas that would be good.
Thanks,
Alan
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