I am putting a strong assumption that he has the same problem that a large chunk of players like myself have called 'ruralistis' or 'farmlandempti' where if you aren't in a large city or on a coast, your pokemon spawns for the first 8 months of the game were limited to pidgeys and rattatta and once in a blue moon there might be something amazingly rare like a Weedle, because our town data wasn't in the data source they used to calculate biomes.
Many player have noticed this and have been updating openstreetmaps.org data in hopes that Niantic does a biome refresh and that OSM is actually where they are sourcing their data from.
"updating" OSM = creating parks and rivers where they don't exist. It's an annoyance for OSM maintainers, there's a Slack channel that specifically flags things that look like they might be Pokemon Go users adding bogus features.
Many player have noticed this and have been updating openstreetmaps.org data in hopes that Niantic does a biome refresh and that OSM is actually where they are sourcing their data from.