Like most Sylvia species, the Blackcap (Sylvia atricapilla) has distinct male and female plumages: the male has the small black cap from which the species gets its name, whereas in the female the cap is brown.
The Blackcap is partially migratory; central and northern European breeders winter in southern Europe and north Africa, where the local populations are resident.

1st photo: A singing male. In my yard, Hilversum, The Netherlands, 22 June 2020
2nd & 3rd photo: A male. Naardermeer, Bussum, The Netherlands, 9 April 2019
4th photo: A young female. Landgoed Oostbroek, Utrecht, The Netherlands, 4 September 2018
5th photo: A female. Bird banding site, Naarden, The Netherlands, 8 October 2005