Common Grasshopper Warbler
Main author: Magnus Hellström, September 2014.
Supplemented by: Simon S. Christiansen, September 2014.
Citation: Ottenby Bird Observatory. 2015. Ringers’ DigiGuide – Locustella naevia. www.ringersdigiguide.ottenby.se
Summer sp* sp*
Winter WC* WC*
Young sp: The post-juvenile moult is said to include head and body, but this have been questioned (e.g. by Kennerley & Pearson ), and it may well be that no true moult is conducted – only a prolonged completion of the juvenile plumage. Either way, no coverts, TT or RR are moulted.
Young WC: The pre-breeding moult includes whole plumage. However, a few birds (according to Kennerley & Pearson  probably only young birds) return in spring with some unmoulted outer SS and inner PP.
Adult sp: The post-breeding moult is partial but highly variable. Some birds only include head and body, while others includes a number of (or all) TT, GC, RR and single inner SS. Cramp (1992) mention a single case of an adult that performed a complete post-breeding moult, but such cases should be very rare.
Adult WC: The pre-breeding moult usually includes whole plumage. However, the situation is not fully understood, and spring birds with fresh GC and SS and more worn PP and PC are known. Perhaps such contrasts are created by differentiated periods of moult during winter?
No plumage differences.
Ringers’ DigiGuide is sponsored by: