Is there a significant size difference between Ameraucana sexes?

[GeneGoddess]

i have a dozen straight run Ameraucana chicks that are now about five weeks old. I bought them locally and they were hatched the same day. Four blacks, five blue, and three splash. At this point, I’m about 90% sure of their gender, due to a combination of behaviour, comb color/size, and body size. About half are about 10-25% bigger than their same age siblings and have slightly larger and redder combs and thicker legs. The comb and leg thickness differences are a continuum and some are kind of midway. But the overall body size is very obvious.

For same age chicks (Ameraucana breed specifically), is overall body size a reliable predictor of gender? Individual pics of the combs are in my reply below, but it is way more obvious when they are next to each other.

 

[JedJackson]

At 5 weeks, I'd say no, body size is not the most reliable indicator of sex, because growth rate seems to depend more on individual than on sex in the early stages. Comb/wattle color and development are a much better indicator of sex, and leg thickness is another good one.

And you're definitely right about it being easier to sex them when they're together, in a group. The differences become much more obvious that way. The reason we generally want individual pictures in here is because it is easier to get good, clear, close pictures that way and it helps us to be able to focus on the individual bird in question, to avoid confusion. You likely have the sexing right yourself in this case, but if you want more opinions, 7-8 weeks is the best time to post.

 

[GeneGoddess]

I uploaded pics of them (best view I could get of the combs). I'm sure I'll post again at 2mo, but it will be interesting to see if I'm correct on their genders. Their designations are Black A-D, Blue A-E, and Splash A-C. Numbers are just pic number. Regarding behaviour, the larger ones are more aggressive, tend to herd the others, lost of chest bumping. The smaller are more passive, tend to cower.

Black A: male (larger)

Black B: male (larger, chest bumps others, just ACTS like a cockerel)

Black C: female (smaller)

Black D: female (smaller)

Blue A: unsure? Larger bird/comb

Blue B: male (larger) (eye is fine, just a trick of the light)

Blue C: female (smaller)

Blue D: female (smaller)

Blue E: female (was a bit runty to begin with)

Splash A: male (larger, more aggressive)

Splash B: male (larger, less aggressive)

Splash C: female (smaller, passive)

 

[JedJackson]

Aggressive behavior and chest bumping happens with pullets too, so don't let that be a big factor in determining sex. These are pretty young-- no red on combs, yet. I can give guesses, but they are only that at this point.

Black A - male. Comb is big.
Black B - female. Comb is small.
Black C - female.
Black D - female
Blue A - female at this point.
Blue B - could be either. Lean female.
Blue C - could be either. Lean male.
Blue D - female
Blue E - Lean male. Big comb.
Splash A - could be either. Lean female.
Splash B - male. Big comb.
Splash C - female. small comb.

 

[JedJackson]

They are healthy and cute, btw.

 

[GeneGoddess]

My husband is CONVINCED that black B is a male. S/he is the friendliest and most fearless. Loves to be carried around, herds the others, chest bumps the others, etc. And is the only one with a name (Henry).

I’m still a scientist at heart, so I can’t help observation and documentation. My dream career was animal behaviorist.

 

[JedJackson]

My husband is CONVINCED that black B is a male. S/he is the friendliest and most fearless. Loves to be carried around, herds the others, chest bumps the others, etc. And is the only one with a name (Henry).

I’m still a scientist at heart, so I can’t help observation and documentation. My dream career was animal behaviorist.

Awesome career. I think most of us in here have a little of that in us.

As far as black B goes, I'm going by the small comb. Things could obviously change since they are only 5 weeks old. However, it is not unusual at all for pullets to be top dogs at that early stage. Personality and vigor wins out.