Baseline shift affects birders' perspectives

What you see is what you know.

That makes it hard for me to explain clearly what it was like 30 or 40 years ago when there were more birds in the woods or our yards than you or I see now.

I would be trying to make you understand what is called my baseline, the number of individual birds I saw 40 years ago. Call it my impression of quantity. But your baseline is likely newer than mine, making it different, sometimes much different.

This sliding standard is known as shifting baseline syndrome — a gradual change in our accepted norm for ecological conditions.

The phrase describes an incremental lowering of standards that results with each new generation lacking knowledge of the historical, and presumably more natural, condition of the environment. It can happen to birds, mammals, plants, insects — to any living thing.

That shift can make discussion of declining bird numbers difficult, whether we're talking about stadium glass or habitat loss or cats on the prowl. This is important when bird conservation is discussed. Someone with a baseline formed decades ago could see more urgency to the issue than might a newer birder.

What does fewer mean? What does it look like?

I can't picture that. The most birds I've seen in one place was a flock of snow geese in Nebraska five years ago, spring migrants resting in rainwater ponds. They took flight as a mass — my guess is a quarter million birds. We were a half mile away when we heard them rise. It looked like an explosion, this shape expanding up and out. It was quite a sight.

Hard to picture. You had to be there.

Bob Janssen is a Minnesota birder with a historic baseline. Now 82, he began birding when he was a child. Over the years he has seen 225 or more species of birds in all but six Minnesota's 87 counties.

He is still birding, with an eye on those six counties. If you add up all those county numbers, his total is 21,047 individual birds of all species (as of Sept. 5).

Does he think other birders have a chance to surpass his totals? (A half dozen or so birders are working on it.)

"There certainly are fewer and fewer birds as each year passes," he said. "It's much more difficult now to find migrant species."

Birders have a word for the sudden appearance of a group of migrating birds in the trees and shrubs around you: fallout. Often composed of warblers, fallouts are flocks of assorted migrants feeding on the move, here for you to see, then moving on.

A fallout in Janssen's most fruitful birding years would mean "swarms of warblers," he said, counting and identifying them difficult for sheer numbers.

Today, the term fallout is used for as few as a dozen birds.

On the positive side of today's birding scene, Janssen has finished writing a book detailing bird species to be found in each of Minnesota's state parks. It will be a Department of Natural Resources publication, hopefully available next year.