Where to Find and Catch Rowlet
From Pokemon Go Wiki
Rowlet are found and captured in Nest and Habitat locations.
Nests
Rowlet Nests are locations that consistently spawn Rowlet.
Habitats
Rowlet Habitats are spawn locations where Rowlet 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: