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That thing called migration

October 23, 2016
Kevin Williams - Grundy County Conservation Director , Reinbeck Courier

Last week's column got me thinking more about migration. Migrators seem to have two basic strategies do a mass movement or go it solo.

Mass movements are not uncommon. I have read about flocks of northern mallards leaving Canada in such huge numbers that they can be tracked by radar to Mexico. That strategy makes sense to me. That whole safety in numbers thing.

Yet other birds are solitary migrators and shun the company of others of their kind. Some of the most determined solo fliers are our little humming birds. They don't even tolerate each other around the feeders all that well. The males leave early on their own solo flights that lead them out across the Gulf of Mexico to the Yucatan Peninsula, a nonstop flight of more than 500 miles.

Our summer goldfinches have finished their nesting and are headed south. These will be replaced by their northern relatives who will then be our resident winter birds - our winter goldfinches, juncos, and sparrows.

Birds aren't the only ones migrating. Several species of bats migrate just like the birds. Some of them look for nice protected roosts and may try to enter buildings. One of the most famous migratory species of all, the monarch butterfly, is on the move right now. A few lucky folks get to see a large flock of them gather for a night roost on small groves of trees. The monarchs we see next spring will be the great, great, grandchildren of the ones visiting our fall flowers now. Even some dragonflies migrate.

Raptors are migrating and I've seen several species in the past week. They include cooper's and sharp shinned hawks that prefer to follow wooded stream valleys where they can find birds to eat which are their main prey. They sometimes visit bird feeding sites for the same reason. I have also seen white-rumped marsh hawks flying low over farm fields when I've been out and about driving. Females are a little larger and have brown backs while males have beautiful silver gray backs. Their buoyant bobbing and weaving flight low over the corn stalks or CRP prairie stands is always fun to watch.

Although red tailed hawks are resident nesters here, the whole population shifts south. They often follow highways where the ditch grasses provide about the only habitat left for field mice that are their primary food. They hunt from a perch like a highway sign or power pole, but also hunt on the wing.

And then there are the turkey vultures still working the thermals with the migrating red tails. I watched a gathering amount of them the other evening at Wolf Creek Park. At one time I counted 11 in the air above me. They are the supreme soaring bird in most of North America and are often able to ride the air currents for hours without apparently moving a wing.

The last turkey vulture of the season can't be too far away because they hate cold weather. Most of the turkey vultures we see now will winter in the southern United States.

Observing the changing life around me during the fall is likely why it is my favorite season.



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