SUN VALLEY • Some of the early results from a long-term study on the impacts of grazing on sage grouse habitat seem pretty straightforward, others raise more questions.
Take grass height, for example. Karen Launchbaugh was quick to joke with cattle producers that grazing affects grass height. “Obviously,” she said with a laugh.
But what’s not understood is how grass height impacts sage grouse or when grass should be grazed. Two years into a planned 10-year study, University of Idaho researchers have found that sage grouse nests are more successful when there is tall grass within one meter (about a yard). But a question that both researchers and ranchers are asking is whether that tall grass is last year’s growth or this year’s growth.
Researchers measured only the height of the tallest stem this year, they didn’t determine whether it was new or old growth. But since hens select their nesting sites in April and early May, when the new grass is just beginning to grow, it makes sense that hens are using last year’s stems to choose a nesting site. That implies fall grazing might be more important than spring grazing; at least for nest site selection.
Not only will researchers determine the age of the tallest stems next year, but they also want to look at the nesting sites earlier in the year, said Launchbaugh. She is a rangeland ecologist director of the UI Rangeland Center.
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Source: Twin Falls Times News
