Steps to Reproduce:

1. Search hours on end for Alpines. Or spawn them.
2. Tame them
3. Try to breed them.
4. See they don't breed, so open the wiki
5. notice you have either two genderless or female dragons
6. search for a male for hours on end. Or spawn thousands of them and crash your world
7. See that no matter how many you spawn, there're no males

Description of issue:
The wiki states that you need a male and female Alpine dragon to breed and that males have "longer tail feathers with some colours". But no matter how much I search and spawn, no male dragons appear! So breeding is impossible.

The two are actually unrelated. Breeding alpines (And rooststalkers, which are also bugged) used to be possible in previous updates, but is broken in 1.2.11 for some reason. Depending on who you ask, butterfly leviathans are either also bugged or just difficult to breed.

As for the gender differences, just like roosties and leviathans, alps currently have no genders but are planned to in a future update, it sounds like the wiki is a little too cutting edge.