I think they are considered to be predominately single-brooded, unless a nest is destroyed. Then renesting is common.
From: Vermont Birds [mailto:[log in to unmask]] On Behalf Of Walter Medwid
Sent: Monday, July 3, 2017 7:00 AM
To: [log in to unmask]
Subject: [VTBIRD] Chestnut sided warbler question
Do these warblers have more than one clutch in Vermont?