Drought taking a toll on raptors

Scientists are alarmed that Utah's raptors are dying as a result of the ongoing drought plaguing the West.

HawkWatch International announced Wednesday that its monitoring studies show drought has taken a toll on hawks, eagles, falcons and other raptors monitored since 1997. More recently and closer to home, four of Utah's red-tailed hawks outfitted with satellite telemetry transmitters in 2001 have died.

"The prevalence of low numbers of raptors counted during migration in 2001 continues a pattern of significant downturns across most of our sites and species," said Jeff Smith, HawkWatch International's science director.

The results of the long-term raptor migration data and more recent studies were released Wednesday by the local nonprofit group, which tracks raptors that serve as barometers of the earth's health.

Smith said the data were derived from "the world's largest standardized, long-term raptor migration monitoring effort" — an extensive network of 16 raptor migration monitoring sites in 10 states and Mexico, largely focused in western North America.

Over the past 20 years, HawkWatch has tracked 14 different species of raptors at six sites in the interior West — the Goshute Mountains in northeast Nevada, Wellsville in Cache Valley, Bridger Mountains in Montana, Lipan Point in Grand Canyon, Arizona and two sites in New Mexico's Manzano and Sandia mountains.

"Judging from the overall patterns, one thing has become quite clear in the last four years: At all sites there's a downturn in most species that appears to be tied to the drought," Smith said. "We have no definite cause and effect evidence but the circumstantial evidence is compelling."

Further evidence of the drought effects on raptors comes from the fact that four of Utah's red-tailed hawks have died.

Last fall, HawkWatch placed transmitters on the backs of 11 of the birds to track movements and survival patterns. The four birds all perished within six weeks after returning to the United States from wintering sites in Mexico. Three of them died around the Four Corners area, which is where Utah, Arizona, New Mexico and Colorado border each other. Another one died in southern Wyoming, Smith said.

The National Oceanic and Atmospheric Administration, otherwise known as NOAA, has rated the area as suffering from "exceptionally severe" drought conditions.

Smith said it's likely that all four birds died because of competition with drought-stressed coyotes, foxes, golden eagles and great horned owls.

Red-tailed hawks that were in less drought-prone areas of Washington state and British Columbia survived.

"This conspicuously high mortality rate of our telemetered, adult red-tails in one of the most severely affected areas only serves to strengthen our belief that drought is to blame for the downturns in our migration counts," Smith said. "The evidence also suggests that raptors are indeed serving as effective barometers of overall ecosystem condition."

In calling attention to the data, HawkWatch hopes to show that the drought affects more than people's lawns.

"We're seeing dramatic effects," Smith said. "Conservation of water is not only important to decrease our water bills but we should be doing everything we can to conserve because it also affects wildlife."

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