Birdsong recordings via Wikimedia Commons: Robin — Jonathon Jongsma (CC BY-SA 3.0) · Blackbird — Ryan Hodnett (CC BY-SA 4.0) · Wood Pigeon & Chiffchaff — Oona Räisänen (Public Domain) · Wren — Alexander Kurthy (CC BY-SA 4.0) · Song Thrush — Jonn Leffmann (CC BY 3.0)