https://www.gamespot.com/articles/pokemon-go-last-chance-to-catch-legendary-lugia/1100-6457755/

The end of the month is quickly approaching, which means Pokemon Go players only have a few more days to catch its current Legendary. The Pokemon Silver mascot Lugia is scheduled to leave the game on April 2, making this your last opportunity to add one to your collection for the foreseeable future.

Lugia was one of the first Legendaries introduced in Pokemon Go, originally appearing as a Raid Battle boss last summer alongside another Legendary bird, Articuno. Niantic reintroduced Lugia to the game earlier this month, although players will find it is slightly different from its initial run.