As my previous post was so short I am posting another cover sent from Switzerland. Thank you Vural for it.  The stamps are cancelled with Geuensee's pictorial postmark. The bird stamp was issued in 1970.
Great spotted woodpecker (Dendrocopos major) can be found in northern Asia and in Europe.  It has many subspecies.  It feeds mostly on insects and grubs but when these can't be found, it can also eat fruit, seeds, small rodents, eggs etc.