Sunday, October 4, 2009

A Fine Kettle

No, this isn't another cooking post. I'm embarrassed at how long it's taken me to post about what was the most spectacular North American bird phenomenon I observed this year. Every fall many hundreds of thousands of raptors--birds of prey--pack up and fly far south for the winter. Having such a long way to go, they conserve energy by soaring rather than flapping their wings. When they reach rising air currents either created by winds being deflected upward by land features or thermals generated by warm ground, they circle and circle upward and then break away again to glide southward until they reach another updraft. When a migrating hawk sees another riding the currents upward this way he thinks, "Hey! Looks like Harry got a good lift there. I'm going, too!" and joins in. Soon more birds are joining the party and it ends up looking like this:

This awesome formation is called a kettle. During an hour or so that there was the most action I conservatively estimate we saw between four and five hundred hawks. In this case they were Broad-winged Hawks (Buteo platypterus), distinguished by a wide white band on the underside of their tails, that were joined by a few Turkey Vultures (Cathartes aura.)

The location of this particular show was at Nelson Dewey State Park in the southwest corner of Wisconsin. Located on the bluffs above the Mississippi River the park provides some amazing views of the river valley and is something of a lesser known destination compared to Wyalusing State Park a little farther north. Either location is a great spot to stand around doing this (and having a sore neck for a few days after.)

Much farther north, at Duluth, Minnesota the fall hawk migration is even more spectacular. Raptors don't like crossing large bodies of water. So when the ones flying down from Canada encounter Lake Superior they turn and follow the shoreline west. The birds are concentrated in numbers as they pass by aptly named Hawk Ridge where it's common to see thousands of birds pass by in a single day. I've never witnessed it myself, but I hope to some day.

Not all the action was in the sky that weekend, either. Asters were in bloom everywhere signalling that autumn is truly upon us.

And this furry little caterpillar was seen several times.

And, finally, on one of the trails at Wyalusing we encountered this sad reminder. Even in the face of so many birds in one spot we know that if we're not careful, they really can all just go away for good.

2 Responses:

Sunita said...

That must've been an amazing sight!
Somehow I never thought of raptors being the migrating type. Whenever I heard of birds migrating, I always thought of the smaller birds. How odd!

Gallicissa said...

It sure must be an amazing spectacle. I have not yet seen such a large aggregation of raptors in one spot, in this country.