Heterogenous resources across sagebrush type are associated with components of offspring fitness in an avian habitat specialist

• Published in: Biological conservation 2024-05, Vol.293, p.110552, Article 110552
• Main Authors: Cutting, Kyle A., Grusing, Emma C., Messmer, David, Schroff, Sean R., Waxe, James A., O'Harra, Aaron, Sowell, Bok F.
• Format: Article
• Language: English
• Subjects: Heterogeneity; Livestock grazing; Offspring fitness; Sage-grouse; Sagebrush ecosystem; Sagebrush type
• ISSN: 0006-3207
• DOI: 10.1016/j.biocon.2024.110552

Animal species often have diverse requirements at different life history stages. Individuals may best meet these requirements by occupying areas with diverse heterogenous resources. Human activities such as agriculture may affect available habitat and heterogenous resources, but current understanding of possible effects is incomplete. We investigated habitat use and survival of an avian habitat specialist species with broods, the greater sage-grouse, in a landscape with different ecological types of sagebrush communities and livestock grazing. We used data from radio-collared females with broods to evaluate: 1) whether and when broods use heterogeneous resources across different sagebrush types; 2) effects of this heterogeneity on offspring fitness; and 3) management implications of our findings. Using a regression-based framework, we found that 26 of 99 broods capitalized on available heterogeneity by moving among ecologically distinct sagebrush types. The probability of switching was positively related to shrub cover and negatively related to forb cover, and distance to the nearest water tank and mesic area. Broods that switched had greater movement rates which resulted in narrower foraging niche at higher trophic levels. For broods that did not switch, survival was negatively related to Lepidoptera biomass and positively related to slope position, distance to mesic area, and accumulated grass cover. For broods that used heterogenous resources across different sagebrush types, survival remained constant across the range of observed conditions. Our findings provide rare evidence that use of heterogeneous resources can mitigate variation in change related to the environment and livestock grazing on components of offspring fitness. •Heterogeneity of habitat features can increase fitness in animals.•Human alteration including livestock grazing can affect this relationship.•Study evaluates use of heterogeneous resources on offspring fitness in grazed landscape.•Results suggest heterogeneous resources mitigate grazing effects on offspring fitness.•Conservation of heterogeneity of habitat features with implications to grazing management are discussed.