Ambient birds

Passerines would spawn in most biomes and have a bunch of different texture variants. Other potential ideas if you wanted to add more biome specific birds: Gulls and puffins would also do pretty much the same thing except would hunt for fish and would spawn in beaches and stony/snowy beaches respectively. Hummingbirds would pollinate plants and would spawn in flower biomes but wouldn't do anything else too unique although perhaps certain flowers could attract them to one's garden. Crows/ravens would spawn in cold biomes and would scare away zombies. they also could be tamed with iron nuggets as a nod to their passion with shiny objects irl.

woodpeckers would spawn in birch forests and would occasionally attach to the side of logs to peck them