I live in a condo-townhouse development which has a retention pond in the middle and a tidal creek adjoining (not that the latter is important). The pond is stocked with fish and we have a lot of fish-eating birds visit, such as the bald eagle, osprey, egrets and herons of various kinds (not that this is material to my question). We also have the usual mallard ducks, and, on occasion, Peking ducks and wood ducks (again, not material to my question). We also have at least two families of Canada Geese, but more importantly, in the evening we have a large flock of Canada geese who visit. The people feed them and they leave a lot of poop (not that this is material to my question). I wish they would quit feeding them. They are not native and show their gratitude by leaving a lot of fertilizer. But, at last, to get to my question, they always circle the area before coming in for a landing. Why? WAG: to ensure there are no hunters here (?).
Yeah, it’s probably just to scope out the landing site and make sure there aren’t hunters, predators, or other dangers about. Even if there are never any hunters at the pond, they may be hunted elsewhere and it’s better to be safe than sorry.
Scope out the site for predators, but also for wind direction.
Geese are heavy, so they circle the pond and pick a spot on the downwind side, then start descending with the wind coming at them.
Also, “not native”? Are you in North America?
They are Canada Geese. They are not native to the southern USA. They once migrated here during the winter, but returned north to the northern states and Canada. Now that they can find plenty of food here, they stay year round.
Because they can, and if you had wings you’d do the same thing. 
Canada Geese are native as far south as Mexico.
What happens is that local populations migrate a few hundred miles- geese from Canada go to Wyoming, Wyoming geese fly to Colorado, and so on.
Then come springtime they reverse and fly a couple hundred miles back to where they were.
Along they way, they keep an eye out for bodies of water with suitable vegetation, which a nice mowed lawn is.
So, yeah, they are a native species, as opposed to introduced or feral.
But this flock is new to your area.
They are native to this area. They are winter visitors and fly back north in the spring - or once flew back north. They can make a living here now.
Peking duck? Do you mean Anas platyrhynchos domestica?
Those are usually domestic rather than wild.
That’s normal Canada Goose behavior, they aren’t the long-distance migrators some other geese are.
They just find a place with water and grass and plop down there. All over their native range, geese are coming and going.
These might not even be the same geese that wintered over. They may have flown north, and more southerly geese moved in to a place that was goose-friendly.
I meant in my last post not native. Peking ducks are a form of mallard, developed by China for fat. The mallards here are also domesticated. Wild mallards do not stay here in winter.
Mallards move farther when they migrate, they can’t handle cold temps.
Canada Geese are fat and lazy. Find a pond and squat there is their MO.
We maybe should call them US Geese. 
The Canada is said to be the hardest goose to hunt because it’s the smartest and wariest (the snow goose is also tough.)
So it should neither be Canada nor US.
And you look at them and they’re sized right for a roasting pan and they just squat there like they own the joint with their attitude that, “It’s not goose season so we aren’t going to be hunted,” and you just want to take a .22 pellet gun with a scope and put one right between their beady little eyes and say quietly, “That’s what you get for crapping on my lawn and thinking that nobody will hunt you in suburbia!”
The non-migratory sub-species is the Giant Canada Goose and was once thought to be extinct. A population was found and reintroduced in its old haunts. This was considered a conservation success story, but I’m not so sure.
http://nationalzoo.si.edu/scbi/migratorybirds/featured_birds/default.cfm?bird=Canada_Goose