- News Home
17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
- About Us
Stress Test for the Spotted Owl
15 August 1997 8:00 pm
Sitting in the woods waiting for an owl to poop might seem like an unrewarding research assignment. But such tedious field work has enabled researchers to show that logging and roadbuilding can stress out the spotted owl, a threatened species that lives in old-growth forests in the Northwestern United States. The work, reported in this month's issue of Conservation Biology, has raised new doubts about the adequacy of government efforts to protect the owl.
While biologists can monitor an animal's stress by measuring stress hormones in blood, capturing and drawing blood from a wild creature can itself trigger a powerful stress response, biasing a study's results. To study the spotted owl, animal physiologist Samuel Wasser of the University of Washington, Seattle, and his colleagues adopted a stressfree technique he and others had developed a decade ago to monitor animals such as baboons: scoop up the animal's feces, which also contain stress hormones.
They measured levels of the stress hormone corticosterone in fecal samples collected from 16 pairs of spotted owls nesting on the Yakama Indian Reservation in Washington, and from about 150 other owls scattered across the Pacific Northwest. They found that male owls living within 0.41 kilometers of a major logging road or a patch of forest that had been clear-cut within the last 10 years had corticosterone levels almost two times higher than owls living more than 3 kilometers away. Because high stress levels can cut into life-span and reproduction, at least in laboratory animals, Wasser says the results--which he emphasizes are preliminary--raise some questions about the efficacy of federal regulations designed to protect the owl.
One prominent spotted owl biologist fiercely challenges the new study, however. "It is an interesting idea, but I don't trust the results," says Eric Forsman of the U.S. Forest Service's Forest Science Laboratory in Corvallis, Oregon. He says the study's sample size is too small for the researchers to conclude that factors other than logging or roads--such as prey availability--aren't responsible for the measured stress differences. He adds that there's no evidence that the owls' stress levels have cut into reproduction or survival.
A senior federal wildlife manager dismisses the criticism. "You always have dueling biologists," says David Frederick, Washington state supervisor for the U.S. Fish and Wildlife Service, which helped fund Wasser's study. "There is extraordinarily little data out there on disturbance, and now we have a tool that will help us address that issue."