johnc wrote:There are theories that there may be enough people up North using ice eaters and these pumps on refuges to keep water open during freezes so the ducks no longer migrate----I have hunted with ice eaters going in NE Arkansas---I dont think there is enough of that to hold birds up
Cooling lakes and no till farming. It takes snow to move our ducks and mallards down. Freezing is not close to cold enough. We need arctic weather and especially snow. While you mentioned a lack of food, we have a virtually infinite supply if it isn't covered up with too much snow. Mallards just do not show up in force up here most years until it is arctic. My dream season we be a split. We get to hunt October and January. The last day I hunted in mid January I saw thousands of mallards. Then it warmed up and most of the birds headed back north.
Birds roosting in big water staying as far north as they can and eating in massive fields traveling around in huge flocks.
I think those subpopulations of mallards are not harvested at any where nearly the same rates as the mallards that live on smaller water. These birds have been off limits to hunters since December. The mallards that work their way all the way to the Gulf in smaller flocks using smaller water are picked off more frequently and for much longer. It doesn't take too many decades of that before you have changed the average behavior of the birds. The total population is up, but a much greater proportion are birds that have never traveled further south than north central Illinois spending their winters in huge flocks on large bodies of water eating corn. Even those traveling further south, more exhibit this behavior because there are big bodies of water and corn the whole way.