Well my take after years of research,my take from the beginning as I'm old enough to remember killing my share of waterfowl with lead bullets... ducks geese like chickens are attracted to shiny objects as they feed.... the feds imposed lead shot ban over water in the beginning years starting in 1986 as migrating waterfowl feed in sloughs and shallow lakes injesting lead shot as they feed eventually diing a slow death from lead poisoning not as wounded birds but lead shot in the gizzard,sure waterfowl and upland birds can pickup lead shot in fields but after 100's of cleaning upland birds I never came across shot pellets in gizzards or stomachs during cleaning. The feds claim and claimed birds of prey migrate at the same time picking up slowly diing waterfowl to weak to escape hence federally protected birds of prey including eagles, Hawks and owls.
Hated steel shot since day one,cripples,many wounded birds that bled out hours later from steel shot slicing like razor blades missing the vitals head or wing steel didn't have the kinetic energy to make clean kills beyond 40 to 50 yds unless we up'd shot size which results in less pellet payload and more cripples. So here we are, in mn and other states we can still use lead on private land and public habitat hunting land but not waterfowl production area's ( usually water public hunting land).
Canada same, I hunted the last year lead shot was allowed for waterfowl... only over dry land only that year haven't been back to Canada since even tho miss the great waterfowl hunting experience one has hunting in Canada western states offer great hunting opportunities as well,timing is everything. Today shotgun ammunition (steel shot) has come along way in improved quality shotgun ammunition plus alternative non toxic ammo is available with similar results of lead like the old days.