Ann Arbor Pokemon Go

Biomes are zones within Pokemon Go with a specific blend of Pokemon spawns. We have a number to choose from in Ann Arbor (the specific spawns are out of date in some places, I'll update them for the new gen when I get a chance):

• Common (75%) - This is most of town, mostly outside of downtown and away from the river, is a blend of commons like Sentret, Ledyba, Spinarak, Pidgey, and Rattata. Interestingly, there are no species that are especially prevalent compared to other biomes here, though rares like Snorlax and Lapras can spawn. It's one of the best areas to XP grind, since many of the species here are 12 and 25 candy evolvers.
• Common (Alt) (5%) - A variation of the common biome, found in a circle from the Medical Campus north to the bend in Plymouth, stretching from the Broadway Bridge to the VA Hospital. A big difference is that Sentrets are very rare here, where they're the most prevalent spawn in the Common biome. Many rares have a significant (3-6x above average) concentrations here, including Hitmonchan, Hitmonlee, Slugma, Growlithe, Omanyte, and many more.
• Mountain (6.4%) - A broad swath around the river, notably Kerrytown, Water Hill, Bird Hills, and parts of Gallup. A favorite biome of many, it's similar to the common biome, but with many more Eevee, Nidoran, Clefairy, Hoppip, Bellsprout, and Oddish. It's notably where almost all Dragonites spawn, along with most Togetics (not that they're useful, with a 1% base capture rate).
• City (1.2%) - This is roughly the downtown area, south of Ann Street, and can be summed up in one word: Swinhub (formerly, Drowzee), which is above 40% of all spawns here. Other commons here are Wooper, Krabby, Marill, Zubat, Gastly, Sneasel, and Shellder. It's pretty much the only place in town you'll find Jynx, Kabuto, Grimer, Sneasel, and Tauros.
• City (Alt) (0.17%) - A weird little area bounded by Fuller, Glen, Ann, and State, with a similar overall blend to the main City biome. This biome's claim to fame is that it's basically the only place you'll ever find an Aerodactyl in the wild.
• Campus (1%) - Mostly concentrated on the northwest part of campus, near the diag, and a block or so east past State, it also snakes randomly through the downtown biome. The blend is similar to the Common biome, except for the almost complete lack of Ledyba and Weedle. It's pretty much the only place in town you'll find a Porygon, along with Voltorb, Magnemite, Aipom, and Skarmory.
• Water (1.7%) - Water biomes are scattered around the city, with the strongest concentrations on the east side of Gallup, and along the river from Riverside Park through Argo and Bandemer. These consist of about 15 percent each Poliwag, Magikarp, Goldeen, Psyduck, and Staryu, 7% each Slowpoke and Chinchou, 3.5% Remoraid, 2% each Squirtle, 1% each Dratini and Tentacool, and a smattering of mostly evolved versions of these.

There's also a strange thing happening in Ypsi on the tiny phallic peninsula containing Cliffs Drive. It seems like it's the only ground-type Pokemon habitat in the area (maybe Niantic is looking for streets with the word "Cliff" in it?). The upshot is that you'll often find Geodude, Diglett, Rhyhorn, Sandshrew, Cubone, and occasional Onix and Omanyte spawns there. Others are way more common there than in the surrounding area, such as Voltorb, Magnemite, Ponyta, Machop, Doduo, Meowth, and Horsea. Not sure what's going on there, but it's worth hitting up check off some rarities!