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Data for: Differential landscape use by forest owls two years after a mixed-severity wildfire

Citation

Duchac, Leila (2022), Data for: Differential landscape use by forest owls two years after a mixed-severity wildfire, Dryad, Dataset, https://doi.org/10.5061/dryad.12jm63xzf

Abstract

Owls are important avian predators in forested systems, but little is known about landscape use by most forest-adapted owl species in environments impacted by mixed-severity wildfire. To better understand species-specific patterns of post-wildfire landscape use within an owl guild we used passive acoustic monitoring using autonomous recording units. The technology is effective for multi-species surveys, especially if some species are rare, nocturnal, or difficult to detect by traditional means. In 2017 we surveyed the interior and adjacent unburned areas of a 10,700 ha mixed-severity wildfire that burned in 2015 in southwest Oregon. We used occupancy modeling to identify patterns of landscape use by five species of forest owls: barred owls (Strix varia), great horned owls (Bubo virginianus), western screech-owls (Megascops kennicottii), northern pygmy-owls (Glaucidium californicum), and northern saw-whet owls (Aegolius acadicus). Our results showed a positive relationship between increasing fire severity and probability of use by western screech-owls and a similar but somewhat weaker relationship for northern pygmy-owls. Barred owls were rarely detected in severely burned areas and their use decreased with increased fire severity. We observed generally low landscape use for great horned owls, which decreased with increased fire severity and at higher elevations. Thus, four out of the five species appeared to use recently burned forests at different levels, with only northern saw-whet owls showing near-complete avoidance of the burned area. These findings increase our understanding of the basic ecology of each species and highlight the varied use of burned areas within this community. These previously undocumented patterns of landscape use in burned landscapes should provide insights to managers and policymakers in the Pacific Northwest as climate shifts, and fires may increase in size, frequency, and severity.

Methods

This dataset contains five encounter histories and associated environmental covariates for analysis in an occupancy modeling framework. Encounter histories for five forest owl species were generated using passive acoustic monitoring data summarized to a weekly scale. In the binary encounter histories, labeled as such, N/A indicates weeks in which stations were not surveyed, zeros represent weeks in which stations were surveyed but the species was not detected, and ones indicate weeks in which stations were surveyed and the species was detected. Weekly count data are also provided; in this case, rather than a one to indicate a species was detected during a week, we include the number of vocalizations detected within that week.

Environmental covariates are untransformed values from field measurements or remote sensed data. Site covariates are those that do not vary through the season (e.g. fire severity), while survey covariates vary within season (e.g. weekly temperature) and can be used to model within-season heterogeneity in detection probability. Surveys began March 31, 2017.

Usage Notes

ReadMe file is included with descriptions of missing values and definitions of all variables.