Herb Wilson teaches ornithology and other biology courses at Colby College. He welcomes reader questions and comments at.

The path leading to our current understanding of bird migration is a circuitous one. Like most scientific inquiry, observers build on the observations of those that came before them. The notion of standing on the shoulders of earlier observers stems from at least the 12th century to a man known only as Bernard of Chartres.

The notion of migration is implicit in a verse of the Old Testament: stork in the heaven knoweth her appointed times; and the turtledove and the crane and the swallow observe the time of their coming. In the eighth century BC, Homer wrote that cranes flee from the coming of winter.

The fall migration is much more protracted, spanning early August into December for different species. Post breeding dispersal of many species leads to surprising records of vagrant birds. Storms may also displace migrants.

In the Middle Ages, Europeans used Aristotle mistaken observations to explain the arrival of barnacle geese each fall from their high Arctic breeding grounds as a transformation from the stalked, goose neck barnacles found commonly on floating driftwood. We come a long way since then but the history of this misstep is perpetuated in the barnacle goose name.

Humans have certainly been aware for millennia that bird abundance changes through the year. When you depend on birds as part of your diet, failure to pay attention to changes in bird numbers can influence survival. But where did the birds go?

We occasionally see a greater white fronted goose. This widely spread species occurs mostly west of the Mississippi River in North America but also in the Old World, as far west as Greenland.

Some birders will argue that the fall migration beats the spring migration hands down. Sure, spring songbirds are singing with full throat, dressed in Canada Goose Discount Borden Bomber Australia their breeding season finery. But the spring migration is relatively brief.

In recent years, Old World geese visit New England in small numbers. A few pink footed geese have graced us with their presence in cow pastures in Yarmouth. A barnacle goose or two visit northeastern North America each fall. The nearest breeding area for both of these species is Greenland.

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On Oct. 13, Bill Sheehan hit the goose jackpot in central Aroostook County. He found six species of geese. Three species were not surprising: canada goose, cackling goose and snow goose. But he hit the trifecta of rare geese finding a barnacle goose, a greater white fronted goose and a pink footed goose.

A couple of centuries later, Aristotle wrote, creatures can make provision against change without stirring from their ordinary haunts; others migrate as in the case of the crane. He also wrote of the migration of pelicans. So far, so good. Observers surmised that some birds come and go in response to the changing of the seasons.

But barnacle goose? It a peculiar name because these geese are vegetarians and rarely if ever eat intertidal animals. The explanation for the name provides a good opportunity to think about the methodology of science as we seek to better understand the natural world.

Unfortunately, Aristotle also wrote birds decline the trouble of migration and hide themselves where they are. He went to write that some birds hid themselves in holes in the ground, sometimes without their feathers. Some Greeks also believed in transformation. In Greece, the European redstart is a common breeder, migrating to Africa each fall. The European robin is a winter visitor to Greece. Aristotle claimed European redstarts transformed into European robins.

A good time to look at our understanding of migration