Is this a nest?

So on my college campus I've noticed that a magmar and squirtle spawn in the exact same spot. The magmar spawns nearly on top of the poke stop for the building and the squirtle spawns inside an adjacent building. I probably caught 4 of each today, with around an hour or so gap in between.

Is this just coincidence or has a nest migrated to this location? Someone told me that nests are where multiple Pokémon of a species spawn together but for this one particular species seems to consistently appear in one spot throughout the day.