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Habitat management for surrogate species has mixed effects on non-target species in the sagebrush steppe


  • Associate Editor: Jeff Bowman


Management by surrogate species assumes that management prescriptions for the surrogate (target) species have no net negative impacts on non-target species with similar life history characteristics. We examined the effects of mechanical manipulations of sagebrush-steppe designed to reduce cover and improve greater sage-grouse (Centrocercus urophasianus) (here, the target surrogate species) habitat quality on 9 non-target, sagebrush-associated bird species for up to 4 years after the treatment manipulations. Two specific presumptions of management by surrogacy were evaluated: 1) no loss (here, local extirpation) of any non-target species is expected in the management area given similar life history characteristics of the target and non-target species; and 2) change in non-target populations characteristics (here, abundance) should mirror those expected for the target species, which typically implies at best an increase or at worst a neutral response to the management treatment. We grouped the 9 non-target species for analysis into 3 categories based on strength of their respective habitat associations with sagebrush (sagebrush-steppe obligate, sagebrush-associated, and steppe associated). The first category was composed of species that met surrogacy criteria for greater sage-grouse, the second were intermediate, and the third did not meet the criteria. We surveyed for birds in treated and reference areas for presence–absence and estimated abundances using distance sampling. We estimated treatment effects using a conditional generalized linear mixed modeling approach; the first model examined local extirpation likelihoods and the second modeled change in abundance conditioned on the species being present post-treatment. Sagebrush treatments had no effect on probabilities of local extirpation 1–4 years post-treatment (P = 0.99). Models fit to abundance data indicated a small but significant (P = 0.031) reduction in overall abundance in treated areas. Abundance responses for species within groupings (e.g., sagebrush-steppe obligate) lacked consistency, indicating benefits to non-target species are best evaluated at the species rather than group level. © 2014 The Wildlife Society.