Locustella fluviatilis, River Warbler
Passeriformes – Locustellidae
N.B.: Ageing River Warblers in autumn is very difficult. Unlike other long-distance migrants undergoing pre-breeding moult in Africa, there is very little if any wear to adult feathers by the end of the summer. Iris colour could be helpful, but not all birds not showing typical adult-like iris (i.e. rich chestnut colour) are inevitably young birds (see e.g. CZEP20-248 and possibly also CZEP20-291 for such examples). Structure of primary coverts andalula feathers seems to me to be usefull too. But this requires further study. Therefore, have this in mind when using my photos of summer/autumns River Warblers in my gallery as reference.
CZEP18-280
Sex: M, age: 1CY+ (euring: 4), trapped: May, 2018 in Vysočina Region, Czech Republic
CZEP18-365
Sex: M, age: 2CY+ (euring: 6), trapped: May, 2018 in Vysočina Region, Czech Republic
Age is known more precisely as this is a retrap. This bird was ringed as 1CY+ (euring 4) in June, 2017.
CZEP18-394
Sex: M, age: 1CY+ (euring: 4), trapped: June, 2018 in Vysočina Region, Czech Republic
CZEP18-438
Sex: M, age: 1CY+ (euring: 4), trapped: June, 2018 in Vysočina Region, Czech Republic
CZEP18-500
Sex: M, age: 1CY+ (euring: 4), trapped: July, 2018 in Vysočina Region, Czech Republic
CZEP18-679
Sex: U, age: 1CY (euring: 3), trapped: August, 2018 in Vysočina Region, Czech Republic
CZEP18-687
Sex: U, age: 1CY (euring: 3), trapped: August, 2018 in Vysočina Region, Czech Republic
CZEP19-181
Sex: M, age: 1CY+ (euring: 4), trapped: May, 2019 in Vysočina Region, Czech Republic
CZEP20-248
Sex: M, age: 1CY+ (euring: 4), trapped: June, 2020 in Vysočina Region, Czech Republic
CZEP20-291
Sex: U, age: 1CY+ (euring: 4), trapped: July, 2020 in Vysočina Region, Czech Republic
Very interesting bird as it shows some moult of remiges before autumn migration – not only some retrices but also secondary 3 and 4. That is very rare in River Warblers to moult on breeding grounds. Moult of remiges alone is not enough to age this bird as 1CY+ (euring: 4) as both adult and young birds do not moult secondaries in the post-breeding moult. On top of that, iris colour looks more like a 1CY (euring: 3) bird. I am ageing it as 1Y+ because of the structure of primary coverts and alula feathers. I might be wrong, though.
CZEP20-355
Sex: U, age: 1CY (euring: 3), trapped: August, 2020 in Jeseníky Mts., Czech Republic
CZEP21-204
Sex: M, age: 1CY+ (euring: 4), trapped: May, 2021 in Vysočina Region, Czech Republic
CZEP21-284
Sex: F, age: 1CY+ (euring: 4), trapped: June, 2021 in Vysočina Region, Czech Republic
CZEP22-131
Sex: M, age: 1CY+ (euring: 4), trapped: May, 2022 in Vysočina Region, Czech Republic
CZEP22-132
Sex: M, age: 1CY+ (euring: 4), trapped: May, 2022 in Vysočina Region, Czech Republic
CZEP24-128
Sex: M, age: 1CY+ (euring: 4), trapped: May, 2024 in Vysočina Region, Czech Republic
CZEP24-129
Sex: M, age: 1CY+ (euring: 4), trapped: May, 2024 in Vysočina Region, Czech Republic