Hiccup: Thank you for nothing, you useless reptile.
Stoick: Your mother would have wanted you to have it... It's half her breastplate.
Hiccup: I really did hit one!
Gobber: Sure!
Hiccup: He never listens!
Gobber: Runs in the family!
Hiccup: And when he does its always with this disappointed scowl, like some one skimmed on the meat in his sandwich. 'Excuse me barmaid, I'm afraid you brought me the wrong offspring! I ordered an extra large boy with beefy arms, extra guts and glory on the side. This here, this is a talking fish-bone!'
Gobber: Now, you're thinking about this all wrong! It's not so much what you look like, it's what's inside that he can't stand.
Hiccup: Thank you for summing that up!
Gobber: Look the point is, stop trying so hard to be something you're not!
Hiccup: Everything we know about you guys is wrong.
Chosen answer: It is never mentioned. but Astrid only used the term queen as a reference to ants' or bees' hive minds, so as it's referred to as a he every other time, we can assume it's male.
MasterOfAll
Well this was answered in the second film by Hiccup's mother. "Every nest has its Queen... but this is their king!" when she refers to the Alpha, which is a bigger and different dragon than the one in the first film. In this context, the dragon in Part 1 is a Queen, therefore female.
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