According to Kortright (1943) Mallard diet includes
about 3% insects and 6% molluscs. He also states,
"The mallard is one of those ducks which are prone to
gorge themselves on the rotting flesh of salmon in the
rivers of the Northwest".

Mallards (at least the domestic ones) are well known
for eating slugs and earthworms. Slugs are a kind of
mollusc, of course, but I suspect that the molluscs
referred to in Kortright were mussels and small bay
clams. Bellrose (1976) states that 45% of a Mallards
diet in Rhode Island consists of mussels.

I think Mallards eat lots of things which no doubt
explains their ubiquity.

Roger Smith wrote:
>
> Dear all,
>
> I made the following observation recently at a local pond and I was
> wondering if anyone had experienced similar Mallard behaviour:
>
> A male Mallard had a brown salamander in its beak (its beak was at right
> angles to the salamander's longitudinal body axis, gripping the body
> between the fore and hind legs) and when I first saw it it was shaking the
> salamander on the surface of the water (perhaps to try to work a better
> grip) until the salamander stopped moving. It then pushed the salamander
> down into a grassy area beneath the water (indeed it looked as if it was
> prodding it down with its beak) and then dabbled at it. I saw some narrow
> brown parts (strips) being taken into the Mallard's mouth (whether these
> were limbs or not I could not tell) and this continued for about 30 seconds
> or so before the Mallard moved away; I saw no actions on the part of the
> Mallard that would suggest that it swallowed the whole salamander.
>
> Would this be an example of a meat-eating Mallard?; or perhaps there was
> vegetation on the body of the salamander that the Mallard was interested in?.
>
> Yours faithfully,
>
> Roger Smith
> Port Coquitlam, BC. Canada.
> mailto:rgsmith at vcn.bc.ca

--
Mike Patterson
Astoria, OR
celata at pacifier.com

http://www.pacifier.com/~mpatters/bird/bird.html