Don't know about the hybrid business, but we have lived in east central Illinois for 40 years. When we first came here, there were no local geese in the summer. The only ones we saw were the migratory ones flying high in the fall & spring. Soon there were a few that stayed the summer & nested. The fish & wildlife people told us that these were a slightly bigger variety which had been exterminated locally in the pioneer days. There were some survivors & the area was being restocked.
Now we have many more or less nonmigratory geese which disappear when the local lakes freeze over. Large flocks move south & north depending on the weather. I suspect that is what they saw in New York yesterday. Large flocks of geese going south a little ways to try to avoid a little cold. It is a problem resulting from the annual failure of global warming.