Always in Season: Migration central to all bird life
Not all birds migrate, and those that do don't all migrate in the same way. Yet migration is a central fact in the life of many birds — certainly of most species that are encountered here.
Of roughly 300 species recorded for Grand Forks County, only a dozen or so are truly sedentary. These are the chicken-like birds, some owls, some woodpeckers, and chickadees and nuthatches.
Some species are residents here throughout the year, but they move locally. Crows, for example, move from farm shelterbelts to the denser forest sheltering Grand Forks.
Other local species are long-distance migrants. Swainson's hawks move from the plains of North Dakota to the pampas of Argentina.
Yet some birds, such as the horned lark, move only as far as they must to find open ground.
Then there are some birds that come to our area to spend some part of the winter. Best known of these is the snowy owl, an Arctic nester that moves as far south as it must to find abundant food.
Others among our familiar winter birds are migrants. Redpolls, for example, move out of the scrub forest zone to the north of us, sometimes becoming incredibly abundant in winter.
Just as not all birds migrate and don't migrate to the same place, each species has its own migration patterns. Some simply disappear. The Baltimore oriole is prominent in this group. Orioles are flashy birds, and their songs are familiar in spring and early summer. Then they are gone, all the way to South America.
Other local birds are more obvious in migration. Flocks of swallows line overhead wires. Blackbirds do the same. Their flocks come to number thousands of birds. Meadowlarks form flocks, as well, though they are much smaller and much less conspicuous than flocks of some other species.
Other species migrate as individuals, as pairs or in small groups. They can appear almost anywhere, and often to the delight of birders whose mood can be somewhat melancholy as nesting species disappear.
So it was that a pair of waterthrushes brightened the day last week.
The waterthrush is no thrush at all, but a species of warbler. There are nesting reports of northern waterthrushes in North Dakota, but this is largely a species of northern bogs. It pauses here in migration. I see them more often in spring than in fall, but that is probably a function of more acute awareness of arriving birds than it is of the waterthrush's relative abundance in either season.
The northern waterthrush is a small brown bird but not a plain one. It has a distinct stripe across its face and a well-streaked breast. These streaks tend to be continuous; they are not spots or splats but well defined, though ragged, lines.
The waterthrush often tilts forward, with its tail pointing away from its back. This gives it a rather angular appearance.
Waterthrushes are almost always seen on the ground and most often near water. This was the case with the pair that showed up at my place. There had been a light rain, and they were foraging along the edge of the garden.
A waterthrush is usually a solo act. I don't believe I've ever seen more than two at the same time. Since they are not frequent here, every sighting is memorable.
There is another waterthrush species—the Louisiana waterthrush. It doesn't occur here.