California kingsnakes (Lampropeltis getulus) released or escaped on Gran Canary are threatening the island’s biodiversity including the rare giant lizard of Gran Canary. Although 334 have been captured in the last two years, there are thought to be a population of some 1,000 still slithering around the island. It is now considered virtually impossible to extinguish them and efforts are limited to controlling their expansion. They are harmless to humans. More here
No snakes are native to the Canary Islands.