Landscape Change

Climate change and human land use are rapidly altering landscape conditions and habitat for many species of wildlife. In forest ecosystems, historic forest management practices are amplifying the effects of climate change, leading to wildfires of unprecedented size and severity and massive drought-related tree mortality. Needed are forest restoration strategies and practices that create ecosystems more resilient to environmental disturbance while maintaining biodiversity.

Our group works closely with wildlife managers forests to understand and mitigate the effects of environmental change on biodiversity in forest ecosystems. We study a broad range of species using bioacoustics, but conduct extensive research on spotted owls given this species is a focus of many forest management plans and practices.



CA wildfires








Wildfire and Disturbances

Recent changes to the global environment coincide with an increase in the frequency and severity of various ecological disturbances. With the increase in severe fire activity in seasonally dry forests, our group has completed numerous studies of the effects of wildfire on spotted owls in California. Leveraging community theory, our research is designed to uncover patterns of owl diversity as a response to both the relative and combined impacts of environmental disturbances. Our work demonstrates that large severe fires eliminate large areas of suitable spotted owl habitat and cause substantial population declines. Conversely, frequent, lower severity fires with small patches of severe fire lead to heterogeneous forest mosaics that can benefit owl occupancy and foraging.

(left) King fire study area, showing the extent of the fire,
severe fire, salvage logging, and locations used by owls

Jones et al. 2022

(right) Derived annual occupancy from 1989 to 2020 for spotted owl sites grouped by the percentage of the home-range (1500 m) that experienced severe fire (unburned, <50% severe, >50% severe). The grey vertical line on the x-axis between years 2014 and 2015 indicates the timing of the 2014 King Fire and therefore divides pre- and post-fire occupancy trajectories.

Jones et al. 2021b

California Spotted Owl Foraging

For Ceeanna Zulla’s Master of Science project conducted in 2019-2021, we were interested in characterizing habitat conditions associated with successful foraging locations. However, for a cryptic, arboreal species such as the California spotted owl (Strix occidentalis occidentalis), it was challenging to determine these approximate locations and the ability to do so had not been possible prior to technological advancements used in this study. With cooperation from Sierra Pacific Industries, we integrated high spatial and temporal resolution GPS tagging with video nest monitoring to identify foraging movement patterns, predation events, prey species captured, and habitat characteristics at sites where California spotted owls captured prey.

We monitored 15 males and their nests to identify 127 prey capture locations, 91 (72%) of which were identified to a specific prey species using video monitoring. Owls tended to capture woodrats, Neotoma fuscipes, a primary prey species, in areas with more: (i) large-tree forest, (ii) young forest, (iii) medium trees/medium canopy forest, (iv) heterogeneity, and (v) hardwood- conifer edge – while avoiding areas with more medium trees/high canopy forest. Owls primarily captured flying squirrels, Glaucomys oregonensis, a second primary prey species, in areas with more large-tree forest.

This information can be used to strengthen conservation planning by incorporating mechanistic knowledge about which habitats promote the acquisition of key prey, while also integrating conservation plans with forest restoration activities intended to promote resilient landscapes.

Woodrat prey delivery to a juvenile California spotted owl.


Woodrats are a key prey species for spotted owls yet tend to occur in higher densities in younger forests. Intensive trapping work indicates that these younger forests act as sources of woodrats that increase densities in adjacent older forests. Further, spotted owl home ranges containing a mosaic of older and younger forests harbor high abundance of woodrats, which in turn, confer greater hunting success to spotted owls – leading to more energy provided to nestlings

Figure: Examples of landscape composition (heterogeneous or homogeneous) within spotted owl (Strix occidentalis) home ranges surveyed in 2020 and 2021 in the central Sierra Nevada, California, USA. Differences are shown at the scale of a spotted owl home range with both (A) National Agriculture Imagery Program (NAIP) imagery and (B) habitat type (mature, young, and open), and (C) at the scale of a trapping grid visualized with NAIP imagery. (Kuntze et al. 2023a)

(left) Estimated density (±95% CI) of dusky-footed woodrats (Neotoma fuscipes) in 2020 and 2021 within habitat types in the central Sierra Nevada, California, USA. Density is shown as number of woodrats per square kilometer in open habitat, young forest, and mature forest within home ranges classified as heterogeneous and homogeneous.

(right) Estimated monthly consumption rate (±95% CI) of dusky-footed woodrats (Neotoma fuscipes) by spotted owls (Strix occidentalis) within the central and northern Sierra Nevada, California, USA, derived from monitoring and mark-recapture data (survival monitoring) or nest camera data (nest camera) within home ranges classified as heterogeneous or homogeneous.


We have conducted a series of studies leveraging doubly-labelled water techniques demonstrating that climate warming is producing temperatures that exceed physiological limits of spotted owls at low elevations. However, older forest characteristics such as large trees and higher canopy cover can, in some cases, create cooler microclimates that mitigate the physiological stress induced by warming temperatures.

Figure 1: Daily maximum temperatures at five roost sites during sampling periods (20–30 days), where thresholds (dashed lines) indicate species-specific physiological thresholds. At 30 ◦C, spotted owls begin to experience heat stress (grey) and 35 ◦C is the upper critical temperature for spotted owls (red). See McGinn et. al 2023a for more information.

Figure 2: Results from individual analyses. a The average velocity at which a bird was moving during the sampling period was a signifcant predictor for mass-specifc energetic expenditure (r2=0.15, βvelocity=162, p=0.05). b Residuals from that relationship, which correspond to deviations from predicted “non-moving” energetic expenditure, were partially explained by canopy height and exposure. (McGinn et. al 2023c)

Relevant Publications

Jones*, G.M., R.J. Gutiérrez*, D.J. Tempel*, S.A. Whitmore*, W.J. Berigan*, and M.Z. Peery (2016). Megafires: an emerging threat to old-forest speciesFrontiers in Ecology and the Environment 14(6): 300–306.

Jones*, G.M., H.A. Kramer*, W.J. Berigan*, S.A. Whitmore*, R.J. Gutiérrez, and M.Z. Peery (2021b). Megafire causes persistent loss of an old-forest speciesAnimal Conservation.

Kramer*, H.A., G.M. Jones*, S. Whitmore*, J.J. Keane, F.A. Atuo*, B.P. Dotters, S.C. Sawyer, S.L. Stock, R.J. Gutiérrez, and M.Z. Peery (2021b).  California spotted owl habitat selection in a fire-managed landscape suggests conservation benefit of restoring historical fire regimesForest Ecology and Management 479(1):118576.

Kuntze*, C.C., J.N. Pauli, C.J. Zulla*, J.J. Keane, B.P. Dotters, K.N. Roberts, S.C. Sawyer, and M.Z. Peery (2023a). Landscape heterogeneity provides co-benefits to predator and preyEcological Applications, p.e.2908.

McGinn*, K., M.Z. Peery, C. Zulla*, W.M. Berigan*, Z.A. Wilkinson*, J.M. Barry*, J.J. Keane, and B. Zuckerberg (2023a). A climate-vulnerable species uses cooler forest microclimates during heat waves. Biological Conservation, 283.

McGinn*, K., B. Zuckerberg, J.N. Pauli, C. Zulla*, W.M. Berigan*, Z.A. Wilkinson*, J.M. Barry*, J.J. Keane, R.J. Gutiérrez*, and M.Z. Peery (2023c). Older forests function as energetic and demographic refugia for a climate sensitive speciesOecologia, 202831-844.

Tempel*, D.J., R.J. Gutiérrez*, J.J. Battles, D.L. Fry, Q. Guo, M.J. Reetz, S.A. Whitmore*, G.M. Jones*, B.M. Collins, S.L. Stephens, M. Kelly, W.J. Berigan*, and M.Z. Peery (2015). Evaluating short- and long-term impacts of fuels treatments and simulated wildfire on an old-forest speciesEcosphere 6(12): 1–18.

Wood*, C., R.J. Gutiérrez*, and M.Z. Peery (2019). Acoustic monitoring reveals a diverse forest owl community, illustrating its potential for basic and applied ecologyEcology 100(9):e02764.

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