Behavior-specific occurrence patterns of Pinyon Jays (Gymnorhinus cyanocephalus) in three Great Basin study areas and significance for pinyon-juniper woodland management

Abstract

The Pinyon Jay is a highly social, year-round inhabitant of pinyon-juniper and other coniferous woodlands in the western United States. Range-wide, Pinyon Jays have declined ~ 3–4% per year for at least the last half-century. Occurrence patterns and habitat use of Pinyon Jays have not been well characterized across much of the species’ range, and obtaining this information is necessary for better understanding the causes of ongoing declines and determining useful conservation strategies. Additionally, it is important to better understand if and how targeted removal of pinyon-juniper woodland, a common and widespread vegetation management practice, affects Pinyon Jays. The goal of this study was to identify the characteristics of areas used by Pinyon Jays for several critical life history components in the Great Basin, which is home to nearly half of the species’ global population, and to thereby facilitate the inclusion of Pinyon Jay conservation measures in the design of vegetation management projects. To accomplish this, we studied Pinyon Jays in three widely separated study areas using radio telemetry and direct observation and measured key attributes of their locations and a separate set of randomly-selected control sites using the U. S. Forest Service’s Forest Inventory Analysis protocol. Data visualizations, principle components analysis, and logistic regressions of the resulting data indicated that Pinyon Jays used a distinct subset of available pinyon-juniper woodland habitat, and further suggested that Pinyon Jays used different but overlapping habitats for seed caching, foraging, and nesting. Caching was concentrated in low-elevation, relatively flat areas with low tree cover; foraging occurred at slightly higher elevations with generally moderate but variable tree cover; and nesting was concentrated in slightly higher areas with high tree and vegetation cover. All three of these Pinyon Jay behavior types were highly concentrated within the lower-elevation band of pinyon-juniper woodland close to the woodland-shrubland ecotone. Woodland removal projects in the Great Basin are often concentrated in these same areas, so it is potentially important to incorporate conservation measures informed by Pinyon Jay occurrence patterns into existing woodland management paradigms, protocols, and practices.

Regional Context for Balancing Sagebrush- and Woodland-Dependent Songbird Needs with Targeted Pinyon-Juniper Management

“…This disparity is explained in part by the SGI's private lands emphasis and science-based approach that prioritizes removal of early successional conifer expansion among shrub- and herbaceous-dominated landscapes (Falkowski et al 2017; Reinhardt et al 2017). Colloquially known as “phase 1” woodlands (Miller and Miller 2007), these areas are characterized by expansion of conifers into shrublands historically devoid of trees, which are used by pinyon jays in some areas mainly for food caching (Boone et al 2021). Even with the increased attention in sage grouse-focused conifer projects over the past decade, the combined effects of management and wildfire are estimated to have only reduced the conifer footprint by 1.6% across the entire sage grouse range (Reinhardt et al 2020).…”

Regional context for balancing sagebrush- and woodland-dependent songbird needs with targeted pinyon-juniper management in the sagebrush biome

“…This disparity is explained in part by the SGI’s private lands emphasis and science-based approach that prioritizes removal of early successional conifer expansion among shrub and herbaceous dominated landscapes (Falkowski et al, 2017; Reinhardt et al, 2017). Colloquially known as “phase 1” woodlands (Miller and Miller, 2007), these areas are characterized by expansion of conifers into shrublands historically devoid of trees, which are used by pinyon jays in some areas mainly for food caching (Boone et al 2021). Even with the increased attention in sage grouse focused conifer projects over the past decade, the combined effects of management and wildfire are estimated to have only reduced the conifer footprint by 1.6% across the entire sage grouse range (Reinhardt et al 2020).…”

Managing for ecological resilience of pinyon–juniper ecosystems during an era of woodland contraction

“…Recent and projected woodland losses may have cascading ecosystem consequences, including potential reductions in water availability (Morillas et al, 2017), altered energy balance (Royer et al, 2012; Stark et al, 2016), declines in tree‐obligate wildlife species (Bombaci & Pejchar, 2016; Boone et al, 2021), and increases in invasive plant establishment (Flake & Weisberg, 2021). Further, pinyon–juniper ecosystems are central to the worldviews, social identities, and cultural practices of many indigenous peoples.…”

“…Low thinning (the removal of small‐diameter tree classes) and mechanical surface fuel reduction (Huffman et al, 2019) may thus inhibit stand recovery after a die‐off event by removing advanced regeneration and homogenizing surface structures. As a result, uneven‐aged silviculture that manages tree densities across multiple age cohorts and creates a diversity of stand structures (e.g., Gottfried, 2004; Gottfried & Severson, 1994; Page, 2008; Figure 1) may be a more appropriate approach to reducing tree competition while maintaining adequate regeneration, microsite heterogeneity, and providing a diversity of woodland structure that supports important wildlife species, such as the Pinyon Jay (Boone et al, 2021).…”