Where to Find and Catch Starly
From Pokemon Go Wiki
Starly are found and captured in Nest and Habitat locations.
Nests
Starly Nests are locations that consistently spawn Starly.
Habitats
Starly Habitats are spawn locations where Starly is likely to be encountered, but not guaranteed the way a Nest is.
Additional Tips and Information
Best Nests
If you know a really good nest or any of the nests above is really good, list them here: