Great Gray Owls Nesting in Atypical, Low-Elevation Habitat in the Sierra Nevada, California

Polasik, Julia S.; Wu, Joanna X.; Roberts, Kevin N.; Siegel, Rodney B.

doi:10.3356/rapt-50-02-194-206.1

Cited by 2 publications

(1 citation statement)

References 30 publications

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“…Population numbers in the region appear to be relatively stable, but historical detections are too sparse to accurately describe long‐term population trends (Sauer et al, 2017; Wu et al, 2016). Unlike willow flycatchers, great gray owls in California will sometimes utilize nonmeadow herbaceous communities for foraging, such as clearcuts, postfire forest openings, and lava cap vegetation communities (Polasik et al, 2016). Across North America as a whole, great gray owls are predicted to lose up to 94% of their existing range by 2080 under a high emissions scenario (Langham et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Modeling climate‐driven range shifts in populations of two bird species limited by habitat independent of climate

2023

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Ranges of species around the world are expected to contract in response to climate change. Species distribution models (SDMs) are a powerful tool for predicting changes in habitat availability, but the variables selected to create SDMs influence their performance. In addition to climate, habitat characteristics and species traits can play a role in predicting species distribution. In this paper, we consider how variable selection influences the accuracy of SDMs when applied to isolated subpopulations of two widely distributed bird species: great gray owl (Strix nebulosa) and willow flycatcher (Empidonax traillii). In the Sierra Nevada of California, these species are restricted largely to discrete patches of meadow habitat within a forest matrix, providing the potential to identify specific locations to target conservation efforts. We contrast predictions made by SDMs that consider climatic variables alone with those that incorporate both climate and geophysical variables. Adding geophysical variables resulted in differing model predictions. For willow flycatchers, adding geophysical variables improved predictive performance. In the case of great gray owls, models with and without geophysical variables had nearly identical performance under historical conditions but differed starkly in their predictions. The full model (climatic and geophysical variables) predicted habitat availability to decrease moderately, whereas the climate-only model predicted nearly complete loss of favorable habitat by 2099. The climate-only model is consistent with expectations based on previous SDMs of birds across North America, but previous studies also assumed homogeneity in species traits and range-wide habitat requirements. The full model appears more consistent with recent trends in great gray owl numbers in the Sierra Nevada specifically, where the population has remained relatively stable over recent decades. Given contradictions in our model predictions, care should be taken when trying to apply similar SDMs to other systems.

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Section: Introductionmentioning

confidence: 99%

Modeling climate‐driven range shifts in populations of two bird species limited by habitat independent of climate

2023

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Short-term resilience of Great Gray Owls to a megafire in California, USA

Siegel

Eyes²,

Tingley

et al. 2019

The Condor

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ABSTRACT Throughout western North America, longer, hotter fire seasons and dense fuels are yielding more frequent, larger, and higher-severity wildfires, including uncharacteristically large “megafires.” Wildlife species associated with late-seral forest characteristics may be particularly vulnerable to habitat loss stemming from changing fire regimes. The Great Gray Owl (Strix nebulosa) is a state-listed endangered species in California that typically nests in large snags in well-shaded forests adjacent to montane meadows. The 2013 Rim Fire burned 104,000 ha in Yosemite National Park and Stanislaus National Forest, making it the largest recorded fire in California’s Sierra Nevada. The fire perimeter contained 23 meadows known to be occupied by Great Gray Owls during the decade prior to the fire, representing nearly a quarter of all known or suspected territories in California at the time. We analyzed 13 yr (2004–2016) of Great Gray Owl detection/non-detection data from 144 meadows in the central Sierra Nevada, including meadows inside and outside the Rim Fire perimeter in Yosemite National Park and on Stanislaus National Forest. During 3 yr of surveys after the fire, Great Gray Owls were detected at 21 of 22 meadows surveyed within the fire perimeter that were occupied during the decade prior to the fire. Bayesian hierarchical modeling revealed that, rather than decreasing after the fire, persistence of owls at meadows actually increased on both National Park Service (NPS) and non-NPS lands, while colonization rates exhibited no significant change. Within the burned area, these dynamics were unrelated to forest structure variables describing post-fire stands around individual meadows. Notably, post-fire increases in owl persistence occurred both inside and outside the fire perimeter, suggesting factors other than the fire were likely favorable to Great Gray Owls during the post-fire years. Great Gray Owls appear to have been largely resilient to effects of the Rim Fire during the 3 yr after it burned.

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Great Gray Owls Nesting in Atypical, Low-Elevation Habitat in the Sierra Nevada, California

Cited by 2 publications

References 30 publications

Modeling climate‐driven range shifts in populations of two bird species limited by habitat independent of climate

Modeling climate‐driven range shifts in populations of two bird species limited by habitat independent of climate

Short-term resilience of Great Gray Owls to a megafire in California, USA

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