Ehh well, "bird" is very broad terming, considering how birds can
take many different shapes and sizes and to me doesn't feel right to describe Pidgey as just a "bird" because... in my mind that only makes me ask what bird? Its name does refer to pigeons clearly, but then Pidove already is way more serviceable as an undeniable pigeon lookalike, with the exact same eyes and little mass of cartilage on their beaks, which is also fitting as one of the common Pokémon for where the setting of Unova is meant to evoke, New York City.
This topic can probably be made into something essay-length if I went thorough into each and every faunal base covered, but I don't feel like it, but I will mention Gen 7 since that one's collection and level of zoological knowledge within the Pokémon it introduced is seriously so crammed with good animal concepts, no other generation can match. Crabrawler is a coconut crab, Cutiefly is a bee fly, Mareanie and Toxapex are amazing takes on crown-of-thorns starfish, Lurantis is an orchid mantis (BUT the Pokémon isn't actually a Bug-type, not even in the Bug Egg Group, so it's not an insect pretending to be a plant, but the opposite!!), Wimpod is a sea slater... crossed with a horseshoe crab shape-wise, Turtonator is a mata mata turtle, and however you feel about Bruxish, you'll be able to recognize it as being based off the humuhumunukunukuāpuaʻa......... or a kind of triggerfish, Hawaii's state fish
