Birds of the Year on cover from Estonia

This is cover from Estonia with long running series of stamps Bird of the Year. From 2001 Estonian post every year release one stamp in this series. So, we can see birds from three different years:

Red-backed Shrike (Lanius collurio), issued on 13.5.2010.
Gray Partridge (Perdix perdix), issued on 7.3.2013.
Black Grouse (Tetrao tetrix), issued on 3.4.2008.

Thank you, Patrik!