We’re accustomed to seeing crows on the Derby Street athletic field, just hanging around waiting for the crowball game to start. In the last few months they’ve been joined by variable numbers of Canada geese. My assumption has been that the geese are part of the local resident population, maybe the ones that frequent Golden Gate Fields and the neighborhood of the Gill Tract.
Last week, driving by on the way to an appointment, Ron and I noticed another set of birds on the field; ducks, we thought. Returning a couple of hours later, I identified them as cackling geese. They were less than half the size of the standard Canadas with proportionately stubbier bills and shorter necks, and overall darker brown body plumage. Six of them were grazing in a tight cluster. One of the Canadas made what was clearly a threat display—head down, mouth open—at the smaller geese, but they were unperturbed.
The Canada (not “Canadian;” I’m not sure why that’s wrong, but it is) goose is a highly variable bird. Hunters have traditionally designated the larger geese with the resonant calls “honkers” and the smaller types with the higher-pitched voices “cacklers.” Ornithologists eventually recognized eleven subspecies of Canada goose, ranging from the near-swan-sized maxima to the mallard-sized minima, based on physical characteristics, range, and who interbred with whom. All nine were assigned common names, for convenience (some were protected by endangered species legislation) and more or less haphazardly. Minima became known as the cackling Canada goose, or just the cackling goose.
Then, maybe a decade ago, the geneticists got into the act. They determined that the big geese and the small geese formed separate evolutionary lineages that diverged at least a million years ago. The seven large races retained the old names: Canada goose, Branta canadensis. The four small varieties became, collectively, B. hutchinsii.
That created a problem, though: what to call the new taxonomic entity and its subspecies. The American Ornithologists’ Union went with “cackling goose” for the species as a whole. So now, in order to distinguish the smallest subspecies, minima, from the other three, you have to call it the cackling cackling goose. Come on, folks! I think we can do better than that. Why not name it after some notable ornithologist? Surely someone out there deserves a goose.
The geese on the Derby field were, in fact, minimas. In addition to being duck-sized and dark, they lacked the white neck-ring characteristic of the next-smallest subspecies, the Aleutian cackling goose (B. h. leucopareia). Minima, by whatever common name, used to be abundant in California in winter. For undetermined reasons, they’ve shifted their wintering range north to Washington State and Oregon.
You’re more likely to see Aleutians in the Delta and Central Valley, sometimes in considerable numbers. We’ve found them with the sandhill cranes and tundra swans around Thornton. This subspecies is a heartening conservation success story. It was almost wiped out by Arctic and red foxes that had been introduced to its island nesting grounds, but bounced back after the predators were effectively controlled and was taken off the federal endangered species list in 2001. The population rose from a probable low of 790 in 1975 to 60,000 in 2005. In fact, the Aleutian’s recovery may be too much of a good thing, since it’s become something of a pasture pest in its Del Norte County staging area.
As for the other cacklers, Richardson’s cackling goose (B. h. hutchinsii), larger and paler than the Aleutian, winters mostly in the Southwest and along the Gulf Coast and is not a problem for California observers. The largest form, Taverner’s (B. h. taverneri), does occur in northern California. Taverner’s, is something of a birder’s nightmare, almost identical in size, shape, and plumage with the smallest form of Canada goose, the lesser Canada (B. c. parvipes.) The two appear to overlap in winter at Tule and Klamath Lakes. David Sibley deals with the subtleties of field identification on his website (www.sibleyguides.com/2007/07/identification-of-cackling-and-canada-goose). Good luck, is all I can say.
The encounter with the cackling geese reminded me that it’s always a good idea to scan flocks of Canada geese for anomalies. Other species, including greater white-fronted and Ross’s geese, have been known to drop in on resident flocks: geese attract geese. Sometimes the visitors stay for years; Rich Stallcup knows a Ross’s goose that has been hanging around a Sonoma County farm pond for more than a decade. Unlike most other birds, geese are not hardwired to migrate; yearlings learn the route from their elders. They can also unlearn migration. Maybe they wake up on a California golf course some spring morning, remember the tundra—the foxes, the mosquitoes—and the guns of autumn, and think: “The hell with it, I’m staying here.”