Greater Sage-Grouse nest bowls buffer microclimate in a post-megafire landscape although effects on nest survival are marginal. Issue 1 (4th February 2021)

• Record Type: Journal Article
• Authors: Anthony, Christopher R; Hagen, Christian A; Dugger, Katie M; Elmore, R Dwayne
• Is Part Of: Ornithological applications. Volume 123:Issue 1(2021)
• Publication Date: 2021-02-04
• Subjects: microclimate -- nest site selection -- nest survival -- sage-grouse -- sagebrush -- wildfire; Artemisia spp -- Centrocercus urophasianus -- fuego silvestre -- microclima -- selección del sitio de anidación -- supervivencia del nido; Birds -- Periodicals; Birds -- California -- Periodicals; Ornithology -- Periodicals; 598
• DOI: 10.1093/ornithapp/duaa068
• Languages: English
• ISSNs: 2732-4621

Abstract

Abstract: Temperature at fine spatial scales is an important driver of nest site selection for many avian species during the breeding season and can influence nest success. Sagebrush ( Artemisia spp.) communities have areas with high levels of vegetation heterogeneity and high thermal variation; however, fire removes vegetation that provides protection from predators and extreme environmental conditions. To examine the influence of microclimates on Greater Sage-Grouse ( Centrocercus urophasianus ) nest site selection and nest success in a fire-affected landscape, we measured black bulb temperature ( T bb ) and vegetation attributes (e.g., visual obstruction) at 3 spatial scales (i.e. nest bowl, microsite, and landscape) in unburned and burned areas. Nest bowls exhibited greater buffering of T bb than both nearby microsites and the broader landscape. Notably, nest bowls were warmer in cold temperatures, and cooler in hot temperatures, than nearby microsites and the broader landscape, regardless of burn stage. Nest survival (NS) was higher for nests in unburned areas compared to nests in burned areas (unburned NS = 0.43, 95% confidence interval [CI]: 0.33–0.54; burned NS = 0.24, 95% CI: 0.10–0.46). The amount of bare ground was negatively associated with NS, but effects diminished as the amount of bare ground reached low levels. Shrub height and visual obstruction were positively associated with NS during the entire study period, whereas minimum T bb had a weaker effect. Our findings demonstrate that thermoregulatory selection by Greater Sage-Grouse at nest sites had marginal effects on their NS. However, given that increases in vegetation structure (e.g., shrub height) provide thermal refuge and increase NS, vegetation remnants or regeneration in a post-fire landscape could be critical to Greater Sage-Grouse nesting ecology. Lay Summary: Greater Sage-Grouse selection of nest bowls based on background temperature had marginal effects on their nest survival in a fire-affected landscape. Greater Sage-Grouse nest bowls in unburned and burned areas buffered thermal conditions more than nearby microsites and the broader landscape in the Trout Creek Mountains, Oregon and Nevada. Nest bowls were warmer in cold temperatures, and cooler in hot temperatures, than nearby microsites and the broader landscape, regardless of burn stage. Nest survival was higher for nests in unburned areas compared to nests in burned areas. Amount of bare ground was negatively associated with nest survival; and shrub height and visual obstruction were positively associated with daily nest survival, whereas microclimate had a weak effect.