Iran has produced an interesting series of stamps showing birds since 1994, but this one has presented a problem. For me, it looks like a warbler and its general pale appearance suggested that it might be a Desert Warbler (Sylvia nana). I've included a field guide image of the Desert Warbler for comparison. There are at least 3 major differences: colour of eyes and legs, and length of wing. Some points in favour: yellow bill, dark crescent marks behind ear coverts, and dark alula.

I found a few photographs on the web particularly one on a Finnish site.

If anyone would like to comment on this proposal, please email me.