<wards the end of fall term, and into winter break for those who remained in Northfield, Lyman lakes were covered in an enormous honking mass of waterfowl, the majority of which were Canada geese. But now that the last of the water is frozen over, they are gone from campus, and so are many of the birds we are used to seeing at other times of year. This is the effect of migration.
Migration is an important part of life for many birds, and some birds never really stop, continuously following food sources or temperatures. Not all birds migrate, and some birds’ migration patterns are more extreme than others: for example, the black capped chickadee and the downy woodpecker are yearlong residents of campus and the Arb. On the other hand, the ruby throated hummingbird, which summers and breeds here in Minnesota, will fly all the way to Central America to spend the winter in a warm environment with plenty of food.
Some birds have it the other way around, preferring cold weather. It’s a sure sign to birders that winter is coming when the first juncos arrive. Most of them spend their summer breeding season north in Canada, and only move south to the lower states when it is cold enough to suit their tastes.
Back to our friends the geese: they don’t tend to move quite so dramatically. All they want is open water, and they are quite content for it to be a bit chilly. Their range spans the entire continent of North America, and tend towards the top in the summer and the bottom in the winter. Minnesota, as well as most of the northern half of the USA, falls in a zone which holds the northernmost of many of the wintering birds, and the southernmost of the summering ones. Rather than summering here like the hummingbirds or wintering like the juncos, the geese we see here in the fall and the spring are often in transit, with only some choosing to stick around and terrorize students.