2013_Geese's flying in flocks
Geese typically categorized under water fowls seem to gather in plenty late January onwards. It is possibly due to the ending of winter and for breeding.
The annual life cycle for geese begins in late winter when adult pairs return to nesting areas in late February or March, as soon as waters open up.
Egg-laying (1-2 weeks) and incubation (about 4 weeks) generally extend through April, with the peak of hatching in late April or early May, depending on location in the state.
After hatching, goose families typically move considerable distances from nesting areas, appearing suddenly “out of nowhere” at ponds bordered by lawns.
Possibly this explains the sudden large concentration's I witnessed.