Niantic has tweaked Pokémon GO’s Pokémon distributions. On Twitter yesterday, it said people could expect to see some changes when hunting for characters and catching eggs. In general, there should be fewer Pidgeys and Rattatas, which were previously two of the most common characters.
These announcements were framed as discoveries by Professor Willow, Pokémon GO’s professor. In the first tweet, he noted that Pidgeys and Rattatas no longer hatch from eggs. Eevees still do, but no longer appear in 10km eggs. They will only hatch from 5km eggs from here on out. In the second tweet, Niantic confirmed that you’ll now see different Pokémon in areas where the more typical Pidgey, Rattata, and Zubat were prevalent.
Pokémon GO is available for Apple iOS and Android devices.