Male beardies know how to dominate cage mates and other beardies very young. The same actions they would do during breeding is the same actions they do to chase off and dominate other dragons. it's very hard to tell exactly when they learn or are able to follow through with a successful courtship. I have a baby from this season 5-6 months old already going through the same actions with the head bobbing, black beard, and biting behind the neck/pinning. As soon as you start seeing this aggression or change take place you better separate if not done already cause you don't get much more of a warning then that. The youngest I've heard a male successfully mating was at 8 months old. I'm sure younger is possible, as well as some not maturing till 14-16 months or so. Last year my 15 month old male was unsuccessful with mating for whatever reasons, but my 18 month old was able to pin and successfully mate that female in less then two minutes. So yeah there is a wide range in when they become sexually mature. Best off not letting them mate or get the chance till they are full grown adults. Problems with prolapse though unlikely are a much greater risk when the male is not fully developed.
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