Avibase is a multilingual bird database with 1.9 million entries on 10,000 species and 22,000 sub-species. In case you need to know that the Black-crowned Sparrow-Lark is called Saharanvarpuskiuru in Finnish.
The French version of the home page makes me smile. When they ask you to enter a “nom d’oiseau”, this is meant literally (scroll down to the very bottom of the page).