The waves of bird migration

by KEVIN STRAUSS

Since last week, spring is in the air. Temperatures climb into the 60s and our mounds of snow are now a memory. And humans aren’t the only ones who have noticed this. Birds are on their way as well.

Some people think of bird migration as a one-time event each spring: birds aren’t here and then they all arrive. But the reality is far more complicated. Birds often migrate north in waves. When those bird “waves” begin moving north varies with phenological (nature calendar) events like when our yards are snow-free and when the ice breaks up on lakes.

Waterfowl like Canada geese and diving ducks migrate first as the ice beaks up on rivers. This often happens in late March to early April. The “puddle ducks” like mallards come a little later as the lakes break up.

The next wave is the seed-eating migrants like juncos and sparrows. They become more common as melting snow makes it easier for these ground-feeders to find seeds to eat. This wave often arrives in mid-April to early May. We are in that wave right now. Junco flocks are visiting backyards looking for sunflower seeds that other birds knocked from the feeders and that squirrels and mice haven’t found yet. White-throated sparrows the “oh-Canada-Canada-Canada” birds, are singing in our woods right now. Robins are also members of this group. All winter they are eating seeds and they continue eating seeds until the worms tunnel up through the soil later in spring.

Insect-eaters make up the next wave of bird migrants, arriving late April to late May. Winter wrens, brown creepers, flickers and warblers like the yellow-rumped warbler migrate north as the trickle in late April and a flood in May.

Nectar eaters like the ruby-throated hummingbird are the last bird wave to arrive each year. They need to wait until the flowers open to supply them with nectar. Right now the hummingbirds are in southern Indiana. Hummingbirds begin arriving here in mid-May and most of them are here by the end of the month.

With 155 breeding bird species in the northwoods, we should be seeing new birds arriving every week from now until the end of May. So keep your eyes and ears open as our winter migrants return to the northland.