Modeling ecological minimum requirements for distribution of greater sage‐grouse leks: implications for population connectivity across their western range, U.S.A

Abstract

Greater sage-grouse Centrocercus urophasianus (Bonaparte) currently occupy approximately half of their historical distribution across western North America. Sage-grouse are a candidate for endangered species listing due to habitat and population fragmentation coupled with inadequate regulation to control development in critical areas. Conservation planning would benefit from accurate maps delineating required habitats and movement corridors. However, developing a species distribution model that incorporates the diversity of habitats used by sage-grouse across their widespread distribution has statistical and logistical challenges. We first identified the ecological minimums limiting sage-grouse, mapped similarity to the multivariate set of minimums, and delineated connectivity across a 920,000 km2 region. We partitioned a Mahalanobis D2 model of habitat use into k separate additive components each representing independent combinations of species–habitat relationships to identify the ecological minimums required by sage-grouse. We constructed the model from abiotic, land cover, and anthropogenic variables measured at leks (breeding) and surrounding areas within 5 km. We evaluated model partitions using a random subset of leks and historic locations and selected D2 (k = 10) for mapping a habitat similarity index (HSI). Finally, we delineated connectivity by converting the mapped HSI to a resistance surface. Sage-grouse required sagebrush-dominated landscapes containing minimal levels of human land use. Sage-grouse used relatively arid regions characterized by shallow slopes, even terrain, and low amounts of forest, grassland, and agriculture in the surrounding landscape. Most populations were interconnected although several outlying populations were isolated because of distance or lack of habitat corridors for exchange. Land management agencies currently are revising land-use plans and designating critical habitat to conserve sage-grouse and avoid endangered species listing. Our results identifying attributes important for delineating habitats or modeling connectivity will facilitate conservation and management of landscapes important for supporting current and future sage-grouse populations.

Quantifying functional connectivity: The role of breeding habitat, abundance, and landscape features on range‐wide gene flow in sage‐grouse

“…In two cases, we found that sagebrush cover <30% impacted dispersal, with a 10% threshold in the third, suggesting that sagebrush cover <10%–30% reduces gene flow. As with the habitat thresholds, sage‐grouse are capable of dispersal through habitats in which they are unlikely to persist (suggested persistence thresholds are in the range of 40%–65% sagebrush cover; Aldridge, Nielsen, & Boyce, 2008; Wisdom et al., 2011; Knick, Hanser, & Preston, 2013). …”

Conserving migratory mule deer through the umbrella of sage‐grouse

“…Energy development reduces the amount of available habitat and increases anthropogenic disturbance, which reduces lek attendance, nest initiation rates, nesting success, and survival of adult females (Lyon and Anderson 2003, Holloran 2005, Kaiser 2006, Walker et al 2007, Doherty et al 2008, Harju et al 2010, Holloran et al 2010. Additionally, sage-grouse are highly sensitive to other types of human disturbance, such as roads, residential areas, pipelines, vehicle traffic and noise (Johnson et al 2011, Blickley et al 2012, Knick et al 2013, Taylor et al 2013. Following multiple petitions for listing under the Endangered Species Act (ESA) and several years of litigation, the US Fish and Wildlife Service (USFWS) issued a listing of ''warranted but precluded'' in 2010, and agreed to deliver a final decision in 2015 that will determine whether the sage-grouse is listed under ESA or removed as a candidate species.…”

Projecting current and future location, quality, and connectivity of habitat for breeding birds in the Great Basin

“…Endangered Species Act. Occurrence of Greater Sage-Grouse is associated most closely with presence of relatively extensive, contiguous stands of mature sagebrush (Aldridge and Boyce 2007, Hanser et al 2011, Knick et al 2013. Preventing the species' listing is among the highest priorities of resource agencies in the Great Basin.…”