Idaho Statesman 6-4-98

Species lose when rivers dry up
By Susan J. Tweit

In April of 1851, John Russell Bartlett, chief commissioner to the U.S.Mexico Boundary Commission, was tooling across the Chihuahuan Desert in southern New Mexico, mapping the new international boundary. Coming around the base of Cooke's Peak, he rejoiced at the sight of the Mimbres River, "a steak of dark green, resembling a huge serpent," winding its way "as far as the eye could reach" across the desert plain. Bartlett and his survey party spent several days camped in that green area, a shady riverside forest of cottonwood, willow, hackberry and Arizona ash.

Recently, I crossed the Mimbres River a few miles downstream from the site where Bartlett and his party camped. The highway bridge passed over a wide, dry arroyo that gives no hint of Bartlett's serpentlike oasis of riparian forest. In fact, only the highway sign announcing "Mimbres River" suggested a river at all.

I'm a biologist and former desert resident. I know the facts and figures on desert riparian areas perfectly well: In the last century, over 90 percent of the desert's wetlands have dried up, decimated by historical and current mismanagement. Gone are the towering riverside forests, gone are their many residents. I thought I knew all the losses, had already mourned them until I received a copy of a petition to add the yellow-billed cuckoo, a once common resident of western riparian forests, to the Endangered Species List.

I grew up with yellow-billed cuckoos. Their distinctive "kakakakaka ka ka ka ka kow kow kow kow" call announced summer, camping trips, hikes and long hours with nothing more pressing to do than watch the clouds build in the sky.

Yellow-billed cuckoos and broadleaf deciduous trees go together like prairie dogs and burrowing owls: Each depends on the other. Cottonwoods and other broadleaf trees are plagued by outbreaks of tent caterpillars and webworms, colonial insects whose caterpillar stage can easily defoliate whole stands of trees in the summer. Yellow-billed cuckoos seek out and dine on tent caterpillars and webworms, consuming them by the bushel.

Most creatures avoid the caterpillars because they are covered with clumps of irritating or toxic hairs that can clog or puncture the digestive system of animals that eat them. Not the cuckoos.

Yellow-billed cuckoos winter in South America and arrive in cottonwood-willow forests in late June or early July, just in time to dine on the first hatch of tent caterpillars and webworms. Historically, these birds nested from the desert rivers of northern Mexico as far north as British Columbia, following outbreaks of their major food. But as river and stream mismanagement eliminated the cottonwood and willow forests of the Mimbres River and elsewhere, yellow-billed cuckoo populations plummeted. Today, their throaty laughter sounds only along a handful of western streams.

Somehow, I hadn't noticed them disappear. In seven years of living in and studying the Chihuahuan Desert, I realized, I had heard these childhood companions only once.

Recovering these birds, of course, is about more than salvaging a childhood memory. It's about restoring living, vibrant river communities. Simply adding yellow-billed cuckoos to the Endangered Species List will not guarantee this will happen, but it is a first step toward changing the way we manage western rivers and streams. State, federal and tribal agencies control much of the riparian areas where cuckoos once fed and bred, and none consider yellow-billed cuckoos in their current management regimes.

Wildlife (other than huntable or fishable species) has traditionally batted last in riparian area management. That is changing, partly because activist groups have used the Endangered Species Act and other laws to force new priorities. People's attitudes are also changing. It is no accident, for instance, that the only yellow-billed cuckoos I've ever heard in the Southwest were calling from the riparian forest around the headquarters of a ranch owned by Ted Turner, a man who values wildlife over cows.

I'm determined that someday when I cross the Mimbres River on that highway bridge, I'll see a green forest of cottonwood, willow, hackberry and ash winding out of the hills and across the desert plain. And if I stop my car and listen, I'll hear the stuttering calls of yellow-billed cuckoos.