swan id

I can tell em apart up close and by their calls, as I used to raise trumpeters, for the heck of it.  But I think you are in NW ND somewhere, so don't worry about trumpeters there.  There are a few on the far eastern side of the state and in Minnesota and Wisconsin, but any that might hit your teal decoys would definitely be lost.  Wouldn't worry about it. 

trumpeters also have a 8 foot wing span and are quite a bit bigger than tundras

Check this website out.  It has a pic of a Trumpeter next to a few Tundras.  You should not have to worry about anything as long as you stay in the approved hunting unit.
http://www.google.com/imgres?imgurl=http://www.swanparadise.com/image-files/tundra-swan.jpg&imgrefurl=http://www.swanparadise.com/Tundra-Swan.html&h=278&w=400&sz=21&tbnid=nOV2aesdo5ajBM:&tbnh=86&tbnw=124&prev=/images%3Fq%3Dtundra%2Bswan%2Bpictures&hl=en&usg=__1YHz21NyoeRIyhPI_sKCFCanBbw=&ei=ZHmxSvbTBYvmM5q3-PIN&sa=X&oi=image_result&resnum=1&ct=image

Thanks I got the same response from the refuge manager at Lostwood NWR. Not to worry, in fact he said the areas where the 2 species coincide they dont allow hunting.  The subtle differences between the 2 would be to difficult to tell apart on the wing so they only set seasons in areas where hunters dont have to worry about it.    Should you have an opportunity to see them side x side trumpeters would be the 747 and tundras are the 737  Pelicans, the ones with the black wing tips, and the bucket mouth are about that size.  Any way good stuff thanks!

I ordered a pair of swan decoys yesterday.  They're supposed to be great confidence decoys for duck hunting plus I plan on using them for swan since I have a swan tag.