Males Red-backed Shrike have a grey head and a typical shrike black stripe through the eye.
Females and juveniles do not have the black eye mask of the male and are dull brown.
Juveniles are similar to females but differ by the scaly pattern on the mantle (back).

I found this family right in front of the Rozhen Monastery near Melnik.

1st, 2nd & 3rd photo: A juvenile.
4th photo: A male.
5th photo: A female.

Melnik area, Bulgaria, 30 July 2017