NEW SCIENCE: Visualizing Sage Grouse Habitat As “Hubs & Spokes”

Sage grouse conservation measures benefit "umbrella" benefits for other sagebrush-dependent species, scientists say. (Scott Copeland photo)

May 17, 2018

New research helps prioritize sage grouse conservation by ranking the importance of leks to the species’ overall genetic connectivity across the range. Photo: Scott Copeland

Sage grouse genetic connectivity is similar to airline hubs, which gives hope for sustaining the iconic species

The greater sage-grouse, once estimated to have a population of 16 million across the western United States, is now believed to be less than one million. The population decline is related to their habitat, much of which has been degraded by non-native grasses and fragmented by development. Because of the location-specific nature of their mating ritual, greater sage-grouse are particularly vulnerable to habitat disruption. New research builds the case for optimism for this species of concern.

A new collaborative study by researchers from USDA Forest Service Rocky Mountain Research Station, the US Geological Survey, and the University of Waterloo entitled The genetic network of greater sage-grouse: range-wide identification of keystone hubs of connectivity, provides tools for decision makers to inform which areas of habitat are most critical to conserve for the bird.

Researchers at the U.S. Forest Service Rocky Mountain Research Station and the US Geological Survey genotyped 5,950 individual sage grouse using DNA collected from these samples.

This figure depicts the overall ranking of node importance to genetic connectivity across the contiguous range of greater sage-grouse (as measured by “betweenness" calculated in Cross et al. 2018).

This figure depicts the overall ranking of node importance to genetic connectivity across the contiguous range of greater sage-grouse (as measured by “betweenness” calculated in Cross et al. 2018).

They grouped 1,200 leks into “nodes,” or a collection of leks, within the network of greater sage-grouse. The nodes were then categorized as “hubs” or spokes” based on their importance to facilitating gene flow within and across the range of sage-grouse. To visualize how these nodes relate to one another, think of the leks as airports: Denver would be a “hub,” while a smaller town, like Bozeman, would be a “spoke” served by the hub.

In terms of sage grouse, hubs foster gene flow out to the spokes. If a hub were to be lost, the birds in the connected spokes would be at risk of genetic isolation.

This research can help land managers prioritize where to locate a proposed development or management action in light of its proximity to leks of high importance to genetic connectivity — and how restoration or an easement could reconnect the birds with their leks. By ranking the importance of hubs across the range, partners can prioritize where to invest conservation dollars in order to ensure a resilient and viable sage grouse population.

“Say you have a high-priority area for genetic connectivity, and over the years conifers have encroached due to fire suppression. To help preserve that genetic hub, you might consider cutting back the conifers,” said Todd Cross, lead author on the study from the USDA Forest Service Rocky Mountain Research Station.

Hubs were found across the species’ range, with concentrations in northcentral Montana, southern Wyoming/northeastern Colorado, northwestern Utah, and central Idaho. The study showed that this research can also be applied to many of the 350+ species that call the sagebrush home.

“The greater sage-grouse is a great poster-child for western landscapes, but there are other animals like winter mule deer and elk, antelope and pygmy rabbits that may benefit from this research,” says Cross.

“Through this research, we’re getting a picture of how genetics fit into the landscape of the West.”

The Sage Grouse Initiative is a partnership-based, science-driven effort that uses voluntary incentives to proactively conserve America’s western rangelands, wildlife, and rural way of life. This initiative is part of Working Lands For Wildlife, which is led by USDA’s Natural Resources Conservation Service.