This is the mating season for geese (as it is for many other species). The implication is that there will be great attentiveness and tenderness between mates. However, along with this goes protectiveness. When another male wishes to possess your girl, you fight.
A moment of tenderness between Canada Geese: female, left; male, right.
Two male geese do aerial combat over a female. The defender, biting the aggressor, won.