Hi Jeff,

I need to read the entire article, but from the observations on the first page, I find this statement of interest: "....sex ratios were more unbalanced on areas subject to human disturbance." (Johnsgard & Buss, 1956)

http://www.jstor.org/pss/3797149


I realize I am taking this out of context and I am not an authority on this subject (just thought it an interesting subject to bounce off you). I agree with everything you write since it is logical and makes sense. But what I am wondering is: at hatching, sex ratios are near 50:50 since sex determination is relatively random at fertilization and remains that way thru development and I believe the first year (for waterfowl).

A preponderance of males increases with time, and older-aged populations will exhibit a greater disparity than populations having a larger percentage of young birds. If so, are older-aged populations considered "healthy populations"?

Thus I wonder about the ultimate question: why are more females a year killed? I realize they have more stresses (due to energy expenditure with egg laying and rearing a brood or two). But could it also be due to not enough optimum habitat? And an increase in predation resulting from lack of optimum habitat? What was it like before historical records??????

>From I read, there is a link between sexual dimorphism and skewed sex ratios. Those less dimorphic waterfowl have a tendency towards stronger pair bonds and possible monogamy. Thus it may not have anything to do with habitat (i.e. artificial selection) (as I had suggested)........but just based on natural selection. And that is how it has always been and how it will always be.

eric
----- Original Message -----
From: Jeff Kozma
To: aceros at mindspring.com
Cc: Tweeters
Sent: 6/28/2010 6:47:11 PM
Subject: Re: [Tweeters] a question


Eric and Tweeters,

Actually, skewed sex ratios are common in waterfowl and not a result of human disturbed/amended habitat. Many more females a year are killed than males, because females alone incubate and care for the eggs/ducklings. Thus, there are naturally more males in many waterfowl species than females. When a female looses her first nest or brood, she will attempt to renest and thus mate again. Sometimes, her original mate has already left and she must find a new mate...that puts her in direct contention by many males whose mates already successfully nested and/or males that never got to mate originally. This results in a sort of free for all or "rape" (for lack of a better term) and if many males mate with her, they assure that at least some of their genes are passed on as well. I have never heard of a female being killed by this behavior, but it can be disconcerting to watch and see what the poor hen has to endure.

Jeff Kozma

Yakima

j c r underscore 5105 at charter dot net
----- Original Message -----
From: Eric Kowalczyk
To: tweeters
Sent: Monday, June 28, 2010 12:34 PM
Subject: FW: [Tweeters] a question


the answer is instinct and survival of the fittest; if you are concerned about the female being drowned, since drowning a female might be considered not evolutionary adaptive, this might be looked at as aberrant behavior due to skewed sex ratios resulting from human disturbed/amended habitat;.......no morals involved; you are right, these are ducks and to the best of my knowledge, no supreme duck has written a book on morals yet.

just my 2 cents

Eric
Seattle


----- Original Message -----
From: Connie Sidles
To: tweeters
Sent: 6/28/2010 9:33:24 AM
Subject: [Tweeters] a question


Hey tweets, as I work to write my new book about the Fill, I thought of a question I would like to throw out to you (hoping it's not too far off-topic):
Is nature morally black-and-white, or are there moral shades of gray? Or are there no morals at all, and if so, is there good and evil?


Example: Two days ago I watched four male Gadwalls gang up on a lone female and attempt to mate with her. One male would mount her and push her head underwater, meanwhile trying to fight off the other males. One male would eventually push off the copulating male and take his place. This went on and on. The female kept trying to escape (and to keep breathing), but she couldn't get away from so many males. The whole gang disappeared behind some bushes on Main Pond, so I don't know the outcome, but it wouldn't surprise me if the males had drowned the female.


Realizing that ducks aren't people, and that nature is "red in tooth and claw," still, what am I to make of this scene? Where is the good in such an action? Even evolutionary good.


Nature has laws. Were those male ducks breaking the law? I'd be interested in your thoughts. - Connie, Seattle


constancesidles at gmail.com
www.constancypress.com



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