I'm shaking my head here. How could a duck/egg supplier say "no such thing" as a green duck egg? Sounds like they are more common than green/blue chicken eggs! (Mind you, the commercial egg suppliers in Canada would also say "no such thing" to a green chicken egg as well .... )
I agree. My mallards lay blue eggs. Sometimes they are very light blue, other times they look like an Easter Egger egg, and sometimes they are whitish. None seem to be more fertile than the others. My mallards are purebred stock.