Or domestic/mallard hybrids. If he was killing wild, migratory birds, that's one thing. But it's not as big of a deal if the birds were feral domestic ducks. Also depends on the weapon. Blasting away with a day 12 Guage in the city is one thing, but if it were a bb gun out in a semi rural area with mutt species, it's not as big of a deal in my mind.