The latest update in "Pokemon Go" left fans from all over the world confused when it shuffled the locations of nests all over the world. While this migration arrived a little later than anticipated, it made changes that players had never seen before when it arrived.
Forbes reports that when Niantic initially migrated spawning nests in Pokemon Go, there was a list of Pokemon that would entirely change to a different set. For example: an Eevee nest before the update would change to a Starmie nest as it did to all other Eevee nests worldwide. After the next update, those Starmie nests would change to Dratini nests following the same pattern worldwide and so on.
Now, however, Niantic has change the pattern; instead of changing the list where Pokemon the nest are now spawning, the system is now totally randomized. While the rarity of each Pokemon has not changed, a player does not have a method of predicting what nests have changed into other than going and looking for them. This, however, does not affect rarity at all, although such is relative because what could have been a Poliwag nest before could be a Bulbasaur nest now. Staple Pokemon of a specific area, however, will remain the same which include Spearows, Weedles, Caterpies, Pidgeys, Ratattas, Zubats and more.
Heavy says that nests in "Pokemon Go" are those areas in the real world where a lot of Pokemon of the same type spawn repeatedly over a span of time. When these nests migrate, the output would shift from one species of Pokemon to another, so a nest could spawn Bulbasaurs now and Charmanders the following morning. Ever since the latest update had been released last September 26, almost every single nest in the game has reportedly changed in spawning behaviour.
There has not been an official list of changes released by Niantic. However, experts at The Silph Road, a Pokemon Go Reddit community, have discovered that notable nests have changed. Not only do nests spawn different species now, some have moved locations, some remained the same, while some have completely disappeared.