Blink dragons' magical capabilities grows as the individual grows older and gains knowledge and experience. Newborn dragons have brown tail and can’t use magic at all. Over time, starting usually with age of 6-10 they learn one of their natural magical abilities, with teleportation being the most common.
Most of the adults have green or blue tail tip.
The white-tailed elders lead and guide the society.

Tail colors:

Brown – No magical capabilities
Orange – Can use single form of natural abilities
Yellow – Limited ability to use more than one natural abilities
Green – Can use all three natural abilities with limitations
Blue – Have capability to use general magic spells
Violet – Mastery of one of the natural abilities and greater capability with magic in general
Reddish-violet – Mastery of all three natural abilities and great capability to use magic in general
White – Masters of magic, Immortal

Natural Magic:

Blink, Teleportation
Invisibility
Telekinesis