NEW ORLEANS (AP) -- The Interior Department is selling a new duck stamp envelope to raise money for conservation in the aftermath of the Gulf oil spill.

The new duck stamp envelopes, or cachets, were unveiled Tuesday. They feature a silk rendering of a photograph of St. Marks National Wildlife Refuge on the Gulf Coast of Florida, as well as the 2010-2011 federal duck stamp.

They sell for $25 -- $10 more than a duck stamp alone. The extra $10 will be used to buy land for national wildlife refuges on the Gulf Coast.

All migratory bird hunters must buy a duck stamp along with state licenses and permits.

This year's stamp shows an American wigeon painted by artist Robert Bealle of Waldorf, Md.