Hi Tweeters

On Sept. 07, Stuart MacKay said:

(snip)
>There were several mallards diving in
>the main pond at Montlake Fill, presumably going after weeds on the bottom.
>There were a couple of "typical" males and the females also clearly showed
>the
>blue speculum so there is no doubt as to the identity. For once I brought my
>binoculars.
>
>The birds stayed under for several seconds c5. Also some birds tried the
>technique but couldn't quite make it - thrashing away on the surface.
>
>Most bizarre,
>
>Stuart

The first time you see this is somewhat upsetting to the natural order
wherein dabbling ducks float and upend, and only diving ducks dive.

Nothing is simple. I believe I may have related an experience (a fussier way
of saying "Stop me if I've told this one before ...") where I stood on the
little wooden bridge at Jericho Pk. in Vancouver BC and watched several
Mallard ducklings, each about a month old, happily diving in about three
feet of water, repeatedly heading for the bottom like the kids that would
dive for coins around a Matson liner, *to feed on a carp carcass*.

I'm not, as the irreplaceable Anna Russell once said, making this up. Each
fuzzy little urchin would jump-dive like a veteran grebe, propel itself down
to the bottom, grab a mouthful, two, three, of carp and wolf them down on
its way back up for air. All three did this, and I watched in head-shaking
bemusement as sometimes all three worried at the carcass simultaneously like
the world's three warmest, fuzziest, cutest little sharks.

As for adults diving, I'd wonder if food was the objective. It's
disconcerting to see a flock of twenty Mallards in front of you, turn away
to say something to a companion, turn back a few seconds later to see empty
water with ripples. I've observed that, with Mallards and Canada Geese,
diving seems to have a more social context, indicating higher than normal
levels of friction(?), excitement(?), fun(?). Or it may be a part of
preening, a way to blast parasites off the plumage.

For what it's worth, I've never seen Mallards or Canada Geese dive that
weren't washing and preening in a group beforehand (concomitantly, I've
never seen a lone duck or goose dive, though I've observed this behavior
nearly a thousand times at Lost Lagoon in Stanley Pk.). It seems to start
with one bird, then two or three, then the whole lot crash-diving repeatedly.
A typical dive for a Mallard is, as Stuart observed, about 3-5 sec., though
I counted one male down 09 sec.; a Canada Goose typically stays down longer,
about 6-8 sec.

They don't seem to travel far, either one. A Mallard at Lost Lagoon or
Jericho typically travels about 1-2 meters underwater, a goose up to 3-4
meters. Another indication of a non-food motivation is that these are
invariably open-wing dives; the bird dives with its wings almost completely
extended, the least efficient shape for getting around underwater (okay,
okay, you don't have to have the world's most streamlined shape in order to
catch fleeing pond scum).

Now, if we could only teach them synchronised dance patterns in time for
Atlanta...

BTW, Stuart, I don't think you're really 'most bizarre', it's just the
result of those antibodies one gets from a childhood bout of presbyterianism
;-)

Michael Price
Vancouver BC Canada
michael_price at mindlink.bc.ca