Thanks you Jeff.

I knew that a species would lose some females to nest predators but I
had it it mind that might make maybe a 20% difference.

This is the first time in my life I've been in the company of more than
fifty Redheads and the difference in sex numbers appeared to be
stunning, with what seemed to be 2-4X as many drakes as hens. I didn't
count. Now there is a good project. Drive up to Entiat (or over to),
count all the Redheads you can see from the appropriately named Entiat
Park. Then count how many of then are female.

I believe that the species does makes a difference in this. Bufflehead
immediately comes to mind, and from my surveys on Shemya I remember
that every time you would see a male Common Eider, if you looked
closely you could always find a difficult to see female on the same
fucus covered rock.

OK I'll search the web.
Some Google results.

1. Red Fox predation takes a lot of nesting Mallards, but hunters (as
Jeff said) can pretty much make up the difference, so the ratio of
Mallards is about even again at the end of hunting season.

2. Not so with Canvasback. The first year birds and females are more
likely to come in to decoys, and you all know what happens next.

3. The sex ratio difference in diving ducks is higher than dabblers.
Mink might get the blame.

4. A Russian study (Belopol'skii et al. 1975) found that significantly
more male Common Eiders are hatched, but in adults the sex ratio is
remarkably even.

Isn't this interesting?

OK Tweeters here's your extra credit for the week. Locate a large
feeding flock of Wigeon and count the total number of individuals.
Then count the males. You don't need to count the females. We can
subtract. Report your findings to the group.

Alternate assignment. Do swans. or Do Coots.

Am I missing teaching?

Larry Schwitters
Issaquah


On Feb 11, 2007, at 9:43 AM, Jeff Kozma wrote:

> With almost all waterfowl, males usually account for a larger
> percentage of the population. The reason, females suffer much larger
> rates of predation since they are the ones to solely attend the nest
> and young ducklings. The males, as most of us know, have no part in
> raising the young. Instead, they spend their summer days with the
> guys while they molt, leaving the hens to do all the family chores.
> Thus, the population in waterfowl is naturally skewed towards the
> drakes. That is why some hunters (all should) practice "voluntary
> restraint"; where they try to the best of their ability, to harvest
> only drakes. I and a few of my hunting partners practice this, but
> not all hunters do.
>
> This is also they reason that during courtship, you often find 5-6
> drakes following and courting a single hen.
>
>
> Jeff Kozma
> Yakima
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