Laura Erickson's For the Birds

Sometimes birds do something so extraordinary, and something with such an enormous impact on people, that it makes national news—like the flickers that bored holes in the space shuttle, or the Black Vultures that killed newborn livestock in the southeast. But many of the exciting things that birds do, and many of the interesting things that scientists learn about them, deserve to be in the news, even if newspaper editors and TV news producers don’ t realize it.

In a recent issue of Nature, scientists explain how the Eurasian Kestrel, a close relative of our tiniest falcon, finds populations of voles hidden beneath deep grass. Birders and ornithologists have long wondered how birds of prey mysteriously appear where rodent populations are high, even though there don’ t seem to be any external signals that a given spot harbors lots of mice while another doesn’t. But it turns out that voles mark their trail systems with urine, and vole urine strongly absorbs ultraviolet light. In laboratories, under artificial light, kestrels are much better at locating mice with UV light bulbs than with bulbs without UV. And in the field, these researchers discovered that wild kestrels gather and hunt in areas marked with an artificial chemical absorbing UV light much more than they do in areas without this artificial mark.

Think what the earth must appear to a kestrel—what looks to us like an ordinary grassy field is intricately designed with delicate patterns invisible to us. A bird’ s eye view is far more detailed than we mere humans can even imagine.

Canada Geese are also in the news. These intelligent creatures have quickly figured out that their greatest enemies—human hunters—are not allowed to shoot at geese in the very places where humans are most abundant—in cities and towns. So urban goose populations are skyrocketing.

Some metropolitan areas have experimented with transplanting geese to cities that have goose shortages, but this is obviously a shortsighted plan—the remaining geese increase and multiply to reach the same high numbers all over again, while the transplants also increase and multiply to bring goose problems to new areas. Other cities have tried controlled hunting, but any plan that brings guns and city parks together is bound to be controversial, and few people feel comfortable having their tax dollars spent hiring sharpshooters to kill the same geese that their little children feed bread to. So what are cities to do?

One Cornell University wildlife specialist may have found a sensible solution. It turns out that the chemical used to flavor grape chewing gum tastes just awful to geese. Paul Curtis was researching how methyl anthranilate, a naturally occurring plant compound, keeps fruit-eating birds out of cherry orchards, and had an inspiration. Sure enough, geese that ate grass sprayed with methyl anthranilate headed for water to wash away the bad taste, and many left the park altogether.

Of course, regular treatments would be prohibitively expensive and would also repel robins and other songbirds from park lawns, but in conjunction with other programs like planting bad-tasting ground covers may well help cities to curb many of their goose problems in a humane way. The chemical recently received EPA approval, and will be soon be marketed under the name REJEX-IT. Don’t confuse this product with the nasty, lethal RID-A-BIRD—a neurotoxin taken up by bird feet when they land on the poisonous perches. Rid-a-bird should probably be banned outright, but Rejex-it sounds like responsible bird control. That’s why you probably won’ t hear a thing about it on the evening news.