muffs/beards showing up out of the blue *pic added*

[speckledhen]

Are you hatching them under a hen or in a bator? When I hatched sex-link chicks this spring (using a bator), I found this out... At 100F I got 50/50 roos/pullets. At 102F I got 20/80 roos/pullets. I later found out through BYC that male embryos do better at the lower temps, and female embryos do better at higher temps. The difference was NOT that the temperature influenced the gender of the embryos, but that the higher temps killed the males. If this makes sense...

Actually, there are studies that suggest that males survive temp spikes better than females. That means you'll get more males than females, sometimes all-male hatches.​

 

[Cowgirl71]

Quote:
Actually, there are studies that suggest that males survive temp spikes better than females. That means you'll get more males than females, sometimes all-male hatches.

Okay, I've never heard of that before... I did hatch a LOT of chicks this year. I didn't hatch, like, 5 @100F, and 5 @102F. I hatched three batches totaling about 40 chicks at 100F, and got 50/50. And then I hatched four more batches totaling about 40 chicks at 102F, and got 20/80. So this was a pretty large sample set. The eggs always came from the same birds... a BO roo and 9 BR hens.

 

[speckledhen]

I'm sure there are exceptions like yours, but I'll check for the reference for you and post it. The subject always comes up when someone asks if incubation temps affect sex (no, they don't change or determine sex) like it does with reptiles.



Here is an article about incubation temps in regard to sex which mentions what I was saying before:

www.ncbi.nlm.nih.gov/pmc/articles/PMC1629050/pdf/rsbl20040247.pdf

However, in megapodes, birds who incubate their eggs in mounds and do not actually sit on them, what you experienced seems to be possible:

Incubation temperature and avian sex ratios -- Although common in reptiles, incubation temperature has not been considered to be a factor in determining sex ratios in birds. However, Goth and Booth (2005) found that incubation temperature does affect sex ratios in megapodes, which are exceptional among birds because they use environmental heat sources for incubation. In the Australian Brush-turkey (Alectura lathami), a mound-building megapode, more males hatch at low incubation temperatures and more females hatch at high temperatures, whereas the proportion is 1:1 at the average temperature found in natural mounds. Chicks from lower temperatures weigh less, which probably affects offspring survival, but are not smaller. Megapodes possess heteromorphic sex chromosomes like other birds, which eliminates temperature-dependent sex determination, as described for reptiles, as the mechanism behind the skewed sex ratios at high and low temperatures. Instead, Goth and Booth (2005) suggest a sex -biased temperature-sensitive embryo mortality because mortality was greater at the lower and higher temperatures, and minimal at the middle temperature where the sex ratio was 1:1.​

 

[Cowgirl71]

Here's another link that basicly says the same thing: img/smilies/hu.gif" alt="hu" />">http://rspb.royalsocietypublishing.org/content/275/1652/2703.full

I may be wrong, but it has so far worked very well for me. I've noticed far too much of a pattern. It's not like each group averaged 50/50 and 20/80, but each HATCH within each group did too. I'll just try it again next year, with sex-link eggs from different birds...

ETA: I do realize that any sex ratio differences due to temperature is because more of a certain gender is dieing from too high/low temperature. And that the future chick's gender is decided before the egg is even layed.

 

[sevenbabychicks]

Resurrecting this post because this whole temperature-dependent sex thing is so interesting! It makes me remember something I learned in college - that whereas in mammals, XY = male and XX = female, in birds it's the other way around - XX = male and XY = female! In mammals, females tend to be hardier as embryos because of their double Xs - more miscarriages happen to male embryos than female, and girls born prematurely are generally have a better chance of survival than boys (I'm one of these, born 2.5 months early. The doctors told my mother that if I had been a boy, I would've had permanent lung damage and would've only had a 50/50 chance of surviving after birth. Crazy.)

Maybe this makes XX male chicken embryos more able to withstand temp fluctuations? Just a thought

I'll also be following this up with an update about my new chicks' sexes when I figure them out. They were hatched by my broody during a super cold week - most died right before hatching. I worry that the four which did hatch are all roos!

 

[chickendales]

I'm definitely going to keep the pullets. It seems like it's the year of the rooster though... about 75% of the chicks I'm hatching from my own flock seem to be roos!

he looks like he has a beared its just pulled out

 

[georgialee]

This is an old thread that got pulled back up, but you are correct - thats exactly what happened