The fifth Pokémon nest migration caught almost all of Pokémon Go players by surprise. October 19 2016 is the official date of the fifth Pokémon nest migration, with numerous players confirming it by the 20th. A Pokémon nest, for players new to the mechanics of the Pokémon Go mobile game, is an area where a player can usually find spawns of Pokémon of the same species spawning all throughout the day. This usually helps players who aim at collecting specific Pokémon.
When a nest migration occurs, the Pokémon that spawns in a said nest disappear and is replaced into a different set of Pokémon species. The term "migration" is meant to describe how Pokémon that disappears from a particular nest may have transferred into a different nest. A Bulbasaur nest yesterday may now be a Pikachu nest.
The first editions of few nest migrations used to have a seeming pattern on which Pokémon changes to during nest migrations. But given the events of the fourth migration where the migration spawned Pokémon at random. For this fifth migration event, it would seem that the migration may follow the way the last one went.
Several Pokémon fans sent community-based inputs on TheSilphRoad, a website that collects reports from the community to deliver helpful resources for Pokémon go, confirming nest changes happening with the nests near their area. For those still doubtful on the nest migration, TheSilphRoad Nest Atlas resource already labelled October 20 reports as reports after the fifth migration, marking the official nest migration.
As Niantic, the game developer for Pokémon Go, will never confirm what Pokémon will spawn the nests when migration happens. For those players who seek to collect Pokémon and complete their Pokédex, hop on to TheSilphRoad, update on Reddit, or not do any of those and just do yourself a favour, go out and check out the new nest areas and you might be up for a Pokémon surprise.
