7 week old Lavender Orpington

[Ryan A]

No technically both are chickens (the species)

and males are called roosters
and females are called hens

Ok. Let’s agree on that one

 

[Ryan A]

 

[ColtHandorf]

That little one is undoubtedly a cockerel. Additionally behavior has very little bearing on the biological sex of a chicken. Both pullets and cockerels can be equally obnoxious at that age. Development of a bird's wattles and comb at that age is an indicator that the bird in question is male. As he matures, development of sex-specific feathering (pointed hackle and saddle feathers in cockerels, as well as curved sickle feathers in the tail) in addition to crowing and attempting to mount females will be other things to look for.