There are a number of subspecies of the Black Redstart (Phoenicurus ochruros) which differ mainly in underpart colours of the adult males.
In general, seven subspecies are accepted. 
They can be separated into three species groups:
1. European species (grey-bellied): P. o. gibraltariensis (Europe) and P. o. aterrimus (only Iberian Peninsula and Morocco);
2. West Asian species (red-bellied): P. o. ochruros and P. o. semirufus; and
3. Central and East Asian species (red-bellied): P. o. phoenicuroides, P. o. rufiventris and P. o. xerophilus.

The male European species has a clear pale wing-patch and a blackish-grey belly and undertail. 
The male West Asian species has a weak pale wing-patch and a blackish-grey breast and rufous belly and undertail. 
The male Central and East Asian species is quite similar to the latter species but it has no pale wing-patch and shows more rufous then black on the breast.

The female is grey (western subspecies) to grey-brown (eastern subspecies) and lacks the white wing patch.
One-year-old males are similar to females but blacker.
The whitish wing panel of the western subspecies does not develop until the second year.
Black Redstarts often sit upright and constantly flick their orange-red tail.

1st photo: Hortobágy National Park, Hungary, 1 May 2019
2nd photo: Boldogkovaralja Castle, Zemplén Hills, Hungary, 29 April 2019
3rd & 4th photo: Jósvafo, Aggtelek National Park, Hungary, 27 April 2019
5th photo: Polgár Fishponds, Hortobágy National Park, Hungary, 30 April 2019