Why do I keep getting so many males, so few females in my hatches?

[Denninmi]

Something I'm doing wrong, or just dumb, bad luck.

It seems like most of my hatches, I end up with a lot more males than females:

Rouen Ducks hatched May 30-31 -- 5 total, 3 males, 2 hens

Turkeys, hatched May 30-31 -- 6 total, I think it's going to be 4 males and 2 hens, not sure yet though.

Button Quail hatched July 5-6 -- 7 total, 5 males, 2 hens.

Coturnix Quail hatched July 30-31, 8 total, 5 males, 3 hens.

Button Quail hatched August 2-3-4, 7 total, 5 males 2 hens (pretty sure, one is iffy due to coloration but I think its a rooster).

Coturnix Quail hatched August 26-27, 30 total, can't tell yet. I am anxious to see what this ratio turns out like.

Is there something about male eggs that make them tougher/easier to incubate than female eggs, resulting in more males hatching?

I want MORE hens and fewer males, since I'm mostly after eggs.

Now, the only major success in getting hens was in my Isa Browns -- 6 hens, 0 roosters. Of course, I BOUGHT those from the feed store!

 

[FireTigeris]

Because you are lucky...

Really if you flipped a coin that many times (7 or 8) you would not often get 50/50 or better.

because birds males are ZZ and females are ZW the females have a higher chance of having a bad copy of the information that is carried on the gene.

This could make female fetus slightly more fragile.

But you didn't mention a lot of unhatched eggs -

 

[Denninmi]

Quote:
Actually, I did have pretty poor hatch rates:

I started with about 24 duck eggs, but they had been held for up to a month, and some had been exposed to freezing outdoor temps, so not surprised with bad numbers there.

All of the rest were shipped eggs, and I had between 25% and 50% hatch rates, although most of the batches were in the 25% to 30% range.

So yes, there were a lot of bad eggs that didn't hatch.