Hi, I'm new to BYC too, but I've been researching a lot about sexing Ameraucana chicks, which is what yours look like. True Araucana chickens have no tails and are somewhat rare, available from breeders. To add to the confusion, if your "Ameraucana" chick came from a hatchery, it is most likely a nonstandard mixed breed, called an Easter Egger. I have two EEs (favorites!) and one turned out to be a cockerel. (He's the whitish one in my avatar. Brown one is pullet.) Hard to tell from your pics, but an EE roo's comb will turn pink and be more prominent at an early age (mine had bright raspberry comb by 6 weeks) and EE roos of all colors will also get dark red splotches on their upper wings starting around the same age. If I had to guess, I would be suspicious of the one in your last pic, but without clearer pics, it's just a guess.
There are some really great threads about this.
Easter Egger Sexing "tips and tricks" *Pictures Included* is long, but very helpful.
Hope this was useful. Fingers crossed for pullets!
