Populations of sage-grouse have declined in recent decades, and the species’ range-wide distribution across western North America has been reduced to nearly half of its historic distribution. Although the rate of decline of this species has slowed over the past two decades, there is concern for the future of sage-grouse because of its reliance on sagebrush (Artemisia spp.), which is a central component in an ecosystem that has been greatly altered during the past 150 years and is currently at risk from a variety of threats. Not only are healthy stands of sagebrush necessary year-round for sage-grouse to survive, but, during summer, young sage-grouse also require a diverse understory of native forbs and grasses. This vegetation provides protection from predators and supplies high-protein insects necessary for rapidly growing chicks.
In 2014, DOE-ID entered into a CCA with the U.S. Fish and Wildlife Service (USFWS) to conserve sage-grouse and the habitats upon which it depends across the INL Site. This voluntary agreement established a Sage-Grouse Conservation Area (SGCA) where infrastructure development and human disturbance would be limited (Figure 1). To guard against sage-grouse declines, the CCA includes a population trigger that, if tripped by declining male lek attendance, would initiate an automatic response by both the USFWS and DOE-ID. The population trigger is set to trip if there is a 20 percent or greater reduction in the three-year average peak male attendance on a set of 27 baseline leks within the SGCA.
Figure 1. Twenty-seven Baseline Leks (Both Active and Non-active) and Other Active Leks that were Surveyed in 2016. One baseline lek was subsequently reclassified as inactive following the surveys. Also shown are three new leks discovered in 2016.
The CCA established a monitoring program based on this trigger threshold and other criteria (Shurtliff et al. 2016). Part of the program includes annual surveys of sage-grouse leks on the INL Site. A lek is a traditional breeding site, located near nesting habitat, where sage-grouse return each spring to display and mate. Counting males annually at lek sites is the best way to document trends in sage-grouse abundance. Because sage-grouse abundance varies naturally from year to year, biologists use a three-year running average of the peak male attendance across 27 baseline leks to calculate trends relative to the population trigger. In addition, other active and non-active leks on the INL Site are surveyed each year for the purpose of understanding population dynamics.
In 2013, DOE-ID formalized the following three monitoring tasks designed to track the number of male sage-grouse at active leks and document additional active leks on the INL Site. The general tasks and their purposes are:
Lek Census and Route Surveys – Surveys of all active leks on the INL Site, including leks on three Idaho Department of Fish and Game (IDFG) survey routes. A subset of these leks comprise the baseline set to which the CCA population trigger is linked. Inactive leks that are included on IDFG routes or the baseline set are also surveyed under this task.
Historical Lek Surveys – Surveys of sites where sage-grouse have been observed displaying in the past. The purpose is to determine if grouse still use those areas.
Systematic Lek Discovery Surveys – Surveys of poorly sampled regions of the INL Site. The purpose is to discover additional active leks, especially within the SGCA.