Birds
Canada Goose
Branta canadensis · also called Canada goose, Canadian goose
The Canada goose is the black-necked, white-cheeked goose that honks overhead in ragged V-formations every autumn — and, increasingly, the one standing on the office lawn in July, refusing to move. It is one of North America’s great conservation successes and one of its most familiar wildlife nuisances, often at the same time.
Overview
Canada geese breed across Canada, Alaska, and the northern US and traditionally migrate south for winter in loud V-formations. But large resident populations now live year-round across much of the US, southern Canada, and — as an introduced bird — Britain, Europe, and New Zealand, on lawns, parks, golf courses, farmland, and ponds. They are grazing herbivores, cropping grass and grain, and can feed for much of the day.
The V-formation
Flying in a V lets each goose ride the upwash off the wingtip of the bird ahead, cutting flight cost. Instrumented birds position themselves precisely in that lift and synchronise their wingbeats. The lead bird works hardest, so the position rotates, and the honking helps keep spacing.
From near-extinction to overabundance
The “giant” Canada goose was thought extinct until the 1960s, then restocked across the US — often with birds that had no migratory tradition. Combined with a landscape full of mown grass and safe ponds, this produced huge non-migratory populations. The geese most people meet no longer fly anywhere.
Fierce in spring
Nesting ganders hiss, charge, bite, and beat with their wings, and because resident geese nest right beside footpaths and playgrounds, spring conflicts with people are common.
A genuine nuisance
Concentrated resident geese foul grass and water with droppings, damage crops and turf, and are a serious aviation hazard — the 2009 Hudson River airliner ditching was caused by a Canada goose strike. Management is contentious because the birds are so familiar and handsome.
Status
The Canada goose is Least Concern and increasing — among the most abundant waterfowl in North America.
Canada Goose: common questions
Why do geese fly in a V?
Aerodynamics and coordination. Each flapping goose leaves a rotating swirl of air off its wingtips, and just behind and to the side of that wingtip the air is moving upward. A bird positioned there gets a small free lift and can fly with less effort, so a line of birds each staggered off the one ahead forms a V (or a J). Studies with instrumented birds show they position themselves precisely in that updraft and even synchronise their wingbeats to catch it. The bird at the point of the V has no one to draft off and does the most work, so the lead position is rotated, and the honking during flight is thought to help the flock keep formation and spacing.
Why don't some Canada geese migrate any more?
Two things happened. First, the largest subspecies, the "giant" Canada goose, was nearly hunted to extinction and then, from the 1960s, deliberately restocked across the central and eastern US using birds that had lost their migratory tradition. Second, the modern landscape suits a large grazing goose extremely well year-round — mown grass on lawns, parks, golf courses, airfields, and campuses provides unlimited food, ornamental ponds provide water and safety from predators, and hunting is banned in towns. Geese that can eat and stay safe all winter have no reason to fly 3,000 kilometres, so many populations became permanent residents. Migratory Canada geese still exist, but the birds most people encounter are non-migratory.
Are Canada geese aggressive?
During the nesting and gosling-rearing season, yes, especially the males (ganders). A goose defending a nest or young will hiss, spread its wings, lower its head and neck, and charge, and can deliver painful bites and buffeting wing blows. Because resident geese often nest in landscaped areas right next to footpaths, offices, and playgrounds, aggressive encounters with people are common in spring, and the advice is to keep your distance, face the bird, and back away slowly without turning your back or running. Outside the breeding season geese are not aggressive, though bold park birds will approach people for food.
Why are they considered a nuisance?
Large numbers of resident geese concentrated on managed grassland create real problems — each goose produces one to two pounds of droppings a day, fouling lawns, paths, beaches, and swimming areas and adding nutrients that promote algae in ponds. Geese grazing on airfields are a serious aviation hazard; the 2009 "Miracle on the Hudson" airliner ditching was caused by a flock of Canada geese. They also damage crops and lawns by grazing and pulling up turf. Management includes habitat modification, egg addling, hazing with dogs, and regulated hunting, and the birds' familiarity and beauty make lethal control publicly contentious.