Effects of common raven and coyote removal and temporal variation in climate on greater sage-grouse nesting success

• Published in: Biological conservation 2016-10, Vol.202, p.50-58
• Main Authors: Dinkins, Jonathan B., Conover, Michael R., Kirol, Christopher P., Beck, Jeffrey L., Frey, Shandra Nicole
• Format: Article
• Language: English
• Subjects: Aphis; Canis latrans; Centrocercus urophasianus; Common raven; Corvus corax; Coyote; Greater sage-grouse; Mesopredator release; Nest success; Predator management; Weather conditions
• ISSN: 0006-3207; 1873-2917
• DOI: 10.1016/j.biocon.2016.08.011

Predator removal has been simultaneously proposed and criticized as a mitigation measure for low reproductive rates of prey species, including greater sage-grouse (Centrocercus urophasianus; hereafter “sage-grouse”). Depredation of sage-grouse nests can limit their productivity. In Wyoming, lethal removal of common ravens (Corvus corax: hereafter “ravens”) and coyotes (Canis latrans) has been conducted by USDA/APHIS/Wildlife Services (WS) for the protection of livestock. During 2008–2011, we evaluated sage-grouse nest success in study sites (1) where WS initiated a raven removal program, (2) WS removed coyotes, and (3) WS did not manipulate ravens and/or coyotes. Precipitation and temperature were analyzed individually and as interactive effects with coyote removal numbers as sources of annual variation in nest success. Over the course of our study, raven densities decreased at study sites with WS raven removal, while sage-grouse nest success in those study sites was higher during years with reduced raven density. Temperature effects on nest success were dependent on timing with successful nests having cooler temperatures prior to the nesting season (conditions promoting water retention and grass growth) and warmer temperatures the week before nest fate (conducive to degradation of sage-grouse odorants used by mammalian predators). Lower nest success was associated with more lethally removed coyotes interacting with greater precipitation suggesting mesopredator release. Raven removal may have a place in sage-grouse management as an interim mitigation measure when sage-grouse populations are subjected to high densities of ravens. However, long-term solutions are necessary, such as reducing supplemental food sources and perch structures used by ravens. •We quantified sage-grouse nest success relative to lethal removal of predators.•Areas with reduced raven density had increased nest success of sage-grouse.•Precipitation combined with coyote removal was related to lower nest success.•Temperature in April related to grass growth was connected to higher nest success.•Higher temperature the week prior to nest fate was related to higher nest success.