'Spy Cams' Put Lens to Declining Sage Grouse Populations
Maxwell Smart, James Bond and other tinsel-town spymasters have nothing in the way of tricky gadgets over Idaho State University researchers who are trying to determine which predators are eating the eggs of sage grouse.
The ISU researchers are employing miniature, camouflaged infrared cameras to gather irrefutable evidence of which predators are eating sage grouse eggs, and to study a variety of sage grouse nesting behaviors.
Sage grouse are a species of "great conservation concern in the West," says David Delehanty, Ph.D., Idaho State University associate professor of biology. He says the birds' range, distribution and overall population have declined drastically.
A major factor in their decline in some areas is predation of their eggs.
Sage grouse are large, grounddwelling, chicken-like birds that are heavily dependent on sagebrush habitat. Land managers in Western states are collaborating to protect and manage sage grouse populations to keep them from being listed as "threatened or endangered" under the Endangered Species Act.
One finding of their research is that ground squirrels may have been unfairly linked to the predation of sage grouse eggs. Ravens, on the other hand, have turned out to be a major predator of eggs.
Delehanty and Peter S. Coates, Ph.D., believe they are the first to use the cameras in sagebrush ecosystems. The cameras film continous footage of the animals enabling researchers to study the interactions. Coates, a former ISU graduate student, works as a research scientist for the United States Geological Survey.
The scientists first radio-collared sage grouse and then located their nests at various sites in southern Idaho and northeast Nevada. They mounted the cameras for around-the-clock monitoring of the nests.
Three major presumed predators of sage grouse eggs are ravens, ground squirrels and badgers. Some species of ground squirrels were suspected of being predators of eggs because of the remains of eggshells found in their scat and their occurrence near nesting sites.
Video recordings repeatedly show ground squirrels trying to bite through eggs in nests.
The ISU biologists have noted a dramatic increase in the predation of sage grouse by ravens. Raven numbers are increasing near Western sage grouse habitat by 200 to 500 percent due to the expansion of roads, power lines, landfills and agriculture.