Subject: [Tweeters] Re: Diving mallard
Date: Apr 16 11:49:59 2010
From: Michael Price - loblollyboy at gmail.com
Hi Tweets
Not only do dabbblers dive but do so routinely for a number of reasons. As
previously noted, diving is an evasive tactic to escape predators. But in
both Mallards and Canada it seems to have some sort of social/hygiene
function as well; when birds of either species gather and begin preening, an
individual (in the Mallards, almost always a male) will suddenly break off
preening and dive, remaining underwater for up to ten seconds. One by one,
the other birds in the group emulate the behavior until a patch of water
which seconds before had anywhere up to thirty birds floating on it, shows
nothing but widening ripples until each bird re-surfaces. I've observed this
group diving to go on for up to twenty minutes at a time, after which the
birds settle down. They might do this to dislodge parasites, but there seems
to be an elevated level of social excitation whenever this group diving
happens. It seems to happen in small flocks (>50) and when the flock is
comprised---at least for the Mallards---of males and females or males only.
The most unusual Mallard diving I've ever seen was at Jericho Park on
Vancouver's west side where, from the bridge between the east and west
ponds, I watched three small (2-3 weeks old) Mallard chicks repeatedly
diving down through three to four feet of water to scavenge on the corpse of
a large carp lying on the bottom below the bridge. They made it look easy,
as though totally routine behavior for them. When each dive would take one
to the bottom, it would remain at depth for about five seconds, feeding
gluttonously on the carcass. Their mother, perhaps more fastidious, did not
join them.
Michael Price
Vancouver BC Canada
loblollyboy at gmail.com
Every answer deepens the mystery.
- E.O. Wilson
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