Russian Owl Stamps

Today I bought four mint stamps from the former USSR (CCCP):

1. Barn Owl (Tyto alba)

Release date: 1979

Denomination: 10 kopeiki

2. Snowy Owl (Nyctea scandiaca)

Release date: 1990
Denomination: 10 kopeiki


3. Eagle Owl (Bubo bubo) 

Release date: 1990
Denomination: 20 kopeiki


4. Long-eared Owl (Asio otus)

Release date: 1990
Denomination: 35 kopeiki