Scientists tracked sage grouse nest success in southern Oregon, and found that hens avoided sites where conifer cover exceeded 3% within 800m of their nests.
Can you spot the hidden sage grouse hen on her nest? She’s wearing a radio collar to allow telemetry tracking, the methodology used in a new study that explored the impacts of conifer expansion on sage grouse nesting habits. (Photo by Tatitana Gettelman, USGS)
Like all mothers, sage grouse hens want to give their young the best shot at surviving –especially since it’s a predator-eat-grouse world out there.
A recent study by Dr. John Severson from the University of Idaho, co-authored by scientists from the NRCS-led Sage Grouse Initiative, found that most female sage grouse selected nesting sites away from conifers. This likely helps them avoid the predators that roost in trees, like eagles, ravens, or raptors. Instead, the hens chose safer nest sites near sagebrush and other shrubs, which provide chicks hiding cover and plenty of food.
We know that sage grouse prefer wide-open, intact sagebrush habitat, and that the expansion of conifer woodlands is a primary threat to the birds — particularly in the Great Basin. This latest study, published in The Journal of Wildlife Management, evaluated the landscape-scale effects of western juniper expansion in southeast Oregon by monitoring where sage grouse hens decided to nest.
The results confirmed the negative effects of conifer expansion on sage grouse habitat, since the hens nested in areas with little or no conifer cover.
Scientists captured hens in the Warner Mountains of Lake County, Oregon (extending into the corners of northern California and Nevada) and tagged them with radio transmitter collars, using telemetry to locate the female sage grouse nests in 2010 and 2011. Researchers located and surveyed 160 nests and 167 available nest sites.
When trees were present within 800m of potential nest sites, sage grouse instead chose a site where trees were clustered rather than dispersed, suggesting selection for more open habitat.
Shrub cover was also an extremely important variable for hens selecting nest sites. That means managers should try to minimize any impact to surrounding sagebrush shrubs if conifers are removed to increase nesting habitat for sage grouse. For example, hand cutting may be more beneficial than using heavy machinery or broadcast burning techniques.
This research shows that sage grouse will lose nesting habitat as conifer expansion continues. To prevent habitat loss, the Sage Grouse Initiative and our partners are focusing joint resources on removing conifers in priority areas for conservation across the birds’ range.
Thanks to the Bureau of Land Management Lakeview District Office, the Natural Resources Conservation Service through the Sage Grouse Initiative, the Oregon Department of Fish and Wildlife, and the Oregon State Police for providing funding and support for this study.