Up close and personal, September 18, 2025. Our yard, Rondeau Provincial Park, Ontario, Canada. Lots of warbler activity the last two days and this is one of 14 species of warbler that came by the yard. Setophaga pensylvanica The Chestnut-sided Warbler sings two basic songs: one is accented at the end (the pleased-to- meetcha song), and the other is not. Males sing the accented songs primarily to attract a female; once nesting is well underway they switch over to the unaccented songs, which are used mostly in territory defense and aggressive encounters with other males. Some males sing only unaccented songs, and they are less successful at securing mates than males that sing both songs. source-allaboutbirds-org