A cackling goose is spotted in front of a Canada goose. Credit: Courtesy of Bob Duchesne

Seven years ago today, I gave up trying. In my first sentence of that week’s column, I reminded the world that the bird is called a Canada goose, not a Canadian goose. But writers don’t control the headlines or photo captions. Sure enough, that column’s photo was labeled “Canadian goose.” So go ahead, call it anything you want.

I’ve evolved since then. Nowadays, I like to ask myself questions even I can’t answer. For instance, why don’t geese species mix more? I mean, any big flock of geese may contain a wandering member of another species, but seldom do I see a wholesale mixing of multiple species.

Right now, there are big flocks of Canada geese in Maine, but all other species are rare. Right now, there are roughly 35,000 snow geese in Quebec City, but few other species. Right now, there are enormous flocks of greater white-fronted geese along the Mississippi flyway, mostly keeping to themselves. Right now, there are sizable flocks of brant in Jamaica Bay, on the outskirts of New York City, around the corner from Coney Island. Why don’t these migrating goose species mix?

Most other waterfowl flock comfortably together. Along the Maine coast, black, surf and white-winged scoters mix in migration, often accompanied by common eiders. Inland, many freshwater duck species intermingle. Other family groups, like warblers and sparrows, mix gleefully. Not geese.

My first hypothesis is that dietary differences keep the species apart. Canada geese are abundant and widespread, fouling ponds and golf courses across America, with a nesting range that stretches from Georgia to the Arctic Circle. They dine on grasses and sedges early in the season, but readily switch to seeds and berries later, including a fondness for blueberries. They feast on grain in post-harvest fields, especially corn cobs. The other geese don’t do that so much.

For instance, snow geese will eat just about every part of a plant. However, they are partial to eating the roots of starchy plants. They are experts at ripping them from the mud and devouring the tubers, especially American bulrush. In migration, they go to those specific places that have large quantities of their favorite food.

Greater white-fronted geese in migration are more apt to forage in lakes, ponds and marshes. Brant specialize in eating eelgrass and other saltwater vegetation. Perhaps these food preferences keep the flocks separate.

Another hypothesis: perhaps the breeding and migration habits of geese are more rigid. While the Canada goose is as widespread across the continent as pumpkin spice latte, the other geese are more specific. All four species breed across northern Canada. Brant nest almost exclusively along the edge of the Arctic Ocean. In migration, they skirt the edge of Hudson Bay, then take a direct route to their favorite spots on the Atlantic coast. A few get into Maine, exclusively on saltwater, but most winter along the New Jersey shore.

Greater white-fronted geese nest from the west side of Hudson Bay all the way to the Bering Sea in Alaska. In migration, they stick to the Mississippi flyway and the Pacific coastline. Snow geese also nest across the far north. In migration, they hopscotch southward, staging in their preferred food areas before settling in for the winter in the southern U.S. They have favorite migration stops in Vermont and Pennsylvania, but not Maine.

Migrating individuals of these other goose species do occasionally hang out with Maine’s Canada geese in the fall. It’s fun to pick them out of the crowd. Scanning a big flock of all-the-same Canada geese would be boring otherwise.

Or not. Another goose species to watch for looks like a miniature Canada goose. The cackling goose is mallard-size, with a shorter bill, but the plumage markings are otherwise similar. It has the same chin strap. The cackling goose is also a high arctic nester. Most spend the cold months in the central U.S. Some winter along the mid-Atlantic coast. A few are sometimes spotted in Maine this time of year, mixed in with the southbound flocks of Canada geese. Scanning the migrating flocks is like panning for gold. Sometimes you find a nugget.

While you’re at it, keep an eye out for two rare geese visiting from across the Atlantic. Pink-footed geese are European birds, with established colonies in Greenland and Iceland. A few have surprised Mainers several times in the last decade. Barnacle geese share the same range, and the same habit of making rare appearances in Maine. Now that’s gold worth panning for.

Bob Duchesne, Good Birding

Bob Duchesne serves as vice president of Maine Audubon’s Penobscot Valley Chapter. He developed the Maine Birding Trail, with information at mainebirdingtrail.com. He can be reached at duchesne@midmaine.com.