Laura Erickson's For the Birds

In physics, there is a rule called the Heisenberg Uncertainty Principle which, in essence , states that it is impossible to measure both the location and the velocity of a particle at the same moment. One of the corollaries of the principle is that the very act of measuring or observing a particle alters it.

Birds and other living things don t always act the way particles in physics do, but it is true that the very act of observing a bird affects it. Sometimes, the birds are attracted by curiosity to approach an observer. At the Lakewood Pumping Station in Duluth, where I count migrating birds every autumn, hummingbirds often fly within inches of my red hat–in other words, my very presence alters the course of their migration.

Hummingbirds are curious birds who are attracted to bright colors. Although some evidence indicates that they are especially likely to approach items that are the color red, they show curiosity about any item that stands out visually from the greens and browns that dominate a typical landscape. When a hummingbird comes within inches of a person’ s head, you can even watch the Heisenberg principle in reverse. As the hummingbird observes the person , the person’s behavior changes–depending on his persuasion, he either pulls up binoculars for an even better look or pulls up his arms reflexively to protect his eyes.

To get a better look, birders often make pishing or squeaking sounds , or even play recordings, to entice the birds closer, again taking advantage of natural avian curiosity. And again, the very act of observing the birds changes the birds’ activities. When a rare bird that birders especially want to see is discovered, it’s endlessly harassed. It’s frustrating and disappointing to see what lengths some birders will go to to add a new bird–like playing recordings on a nesting ground, sometimes keeping a pair so busy defending their territory that they end up losing their nest and eggs. Believe it or not, in order to see rails and other secretive marsh birds, some birders actually ride in big wheel buggies through the marsh in spring, frightening up the birds and damaging their habitat just so they can check off the bird’s name on whatever list they happen to be working on.

When I was in Texas last month, we went out one night to look at Pauraques at Bentsen Rio Grande Valley State Park. Pauraques are long-tailed relatives of our own nighthawk and Whip-poor-will, and every evening as dusk falls they sit out at roadsides, fluttering up to catch flying insects. They’re easy to see with a flashlight–their eyes are so exquisitely fashioned for nocturnal vision that they reflect back the light like intense little headlights. And Bentsen State Park is the best place to find them, as the birding grapevine has made common knowledge. Which means that now the cars with flashlights cruising the roads at Bentsen every evening vastly outnumber the few remaining Pauraques that can survive under such an onslaught. Perhaps this too is an example of Heisenberg’ s Principle –or maybe it just goes to prove the old maxim that you always hurt the one you love.