Cryptic wide‐ranging movements lead to upwardly biased occupancy in a territorial species

Berigan, William J.; Jones, Gavin M.; Whitmore, Sheila A.; Gutiérrez, R. J.; Peery, M. Zachariah

doi:10.1111/1365-2664.13265

Cited by 33 publications

(38 citation statements)

References 46 publications

(82 reference statements)

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“…It has been shown that even low rates of false positive detections result in positive biases that inflate occupancy rate estimates (Royle and Link 2006, Miller et al 2011, Sutherland et al 2013. We also knew from GPS-tagbased studies of spotted owls that owls frequently move amongst unoccupied (and sometimes occupied) territories (Berigan et al 2018, Blakey et al 2019). Therefore, we were able to exclude false positive detections from our owl detection database because we knew which owls were present at a given historical territory owing to our observation of their colour bands, both before and after the King Fire.…”

Section: The Science Of Spotted Owls and Firementioning

confidence: 99%

“…We had an extensive individual history of owls affected by the King Fire because we had colour-marked and resighted birds in our study area for the 22 years preceding (1993-2014) as well as annually after the King Fire. Knowing the identity of individuals allowed us to associate individuals with places and, more importantly, allowed us to exclude false positive detections in survey/location histories of birds (Berigan et al 2018). Interestingly, studies by Lee et al (2012Lee et al ( , 2013, Lee and Bond (2015) and Hanson et al (2018) on occupancy dynamics of spotted owls showed no negative effects of high-severity fire but relied primarily on night-time detections of unmarked owls to assign the occupancy status, which suggests false positive detections could have been included in analysis (Berigan et al 2018).…”

Section: The Science Of Spotted Owls and Firementioning

confidence: 99%

“…Knowing the identity of individuals allowed us to associate individuals with places and, more importantly, allowed us to exclude false positive detections in survey/location histories of birds (Berigan et al 2018). Interestingly, studies by Lee et al (2012Lee et al ( , 2013, Lee and Bond (2015) and Hanson et al (2018) on occupancy dynamics of spotted owls showed no negative effects of high-severity fire but relied primarily on night-time detections of unmarked owls to assign the occupancy status, which suggests false positive detections could have been included in analysis (Berigan et al 2018). It has been shown that even low rates of false positive detections result in positive biases that inflate occupancy rate estimates (Royle and Link 2006, Miller et al 2011, Sutherland et al 2013.…”

Section: The Science Of Spotted Owls and Firementioning

confidence: 99%

“…The USFS did not request the other information from us because they simply needed to know if any owls had been detected at a site, the pair status, presence of young and the exact location of the birds and nest (if present). As discussed above, without information on individual identity and time of detection during a survey, it was not possible for Hanson et al to eliminate "false positive" detections resulting from owls using multiple territories during their nocturnal activities, which can lead to significant upwardly biased occupancy estimates (Sutherland et al 2013, Berigan et al 2018. As they did not have survey-specific data, Hanson et al (2018) were unable to use standard occupancy modelling approaches that account for imperfect detection (i.e.…”

Section: The Science Of Spotted Owls and Firementioning

confidence: 99%

See 3 more Smart Citations

Megafire effects on spotted owls: elucidation of a growing threat and a response to Hanson et al. (2018)

Jones¹,

Gutiérrez²,

Tempel³

et al. 2019

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The extent to which wildfire adversely affects spotted owls (Strixoccidentalis) is a key consideration for ecosystem restoration efforts in seasonally dry forests of the western United States. Recently, Jones et al. (2016) demonstrated that the 2014 King Fire (a “megafire”) adversely affected a population of individually-marked California spotted owls (S.o.occidentalis) monitored as part of a long-term demographic study in the Sierra Nevada, California, USA because territory occupancy declined substantially at territories burned at high-severity and GPS-tagged spotted owls avoided large patches of high-severity fire. Hanson et al. (2018) attempted to reassess changes in territory occupancy of the Jones et al. (2016) study population and claimed that occupancy declined as a result of post-fire salvage logging not fire per se and suggested that the avoidance of GPS-marked owls from areas that burned at high-severity was due to post-fire logging rather than a response to high-severity fire. Here, we demonstrate that Hanson et al. (2018) used erroneous data, inadequate statistical analyses and faulty inferences to reach their conclusion that the King Fire did not affect spotted owls and, more broadly, that large, high-severity fires do not pose risks to spotted owls in western North American dry forest ecosystems. We also provide further evidence indicating that the King Fire exerted a clear and significant negative effect on our marked study population of spotted owls. Collectively, the additional evidence presented here and in Jones et al. (2016) suggests that large, high-severity fires can pose a threat to spotted owls and that restoration of natural low- to mixed-severity frequent fire regimes would likely benefit both old-forest species and dry forest ecosystems in this era of climate change. Meeting these dual objectives of species conservation and forest restoration will be complex but it is made more challenging by faulty science that does not acknowledge the full range of wildfire effects on spotted owls.

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Section: The Science Of Spotted Owls and Firementioning

confidence: 99%

Section: The Science Of Spotted Owls and Firementioning

confidence: 99%

Section: The Science Of Spotted Owls and Firementioning

confidence: 99%

Section: The Science Of Spotted Owls and Firementioning

confidence: 99%

See 2 more Smart Citations

Megafire effects on spotted owls: elucidation of a growing threat and a response to Hanson et al. (2018)

Jones¹,

Gutiérrez²,

Tempel³

et al. 2019

View full text Add to dashboard Cite

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“…For example, spotted owls typically show high site fidelity (Forsman et al 2002;Blakesley et al 2006;Ganey et al 2014b), and resident owls may therefore continue to occupy territories immediately following fire even if the habitat within those territories is severely degraded (Ganey et al 2017). More importantly, recent data on movements of Global Positioning System-tagged California spotted owls suggest that, at least for that subspecies, occupancy rates estimated based on locations of unmarked owls may badly overestimate true occupancy rates (Berigan et al 2018;Blakey et al 2019). Further, in a long-term study involving uniquely marked northern spotted owls, Rockweit et al (2017) found that occupancy rates in severely burned territories remained relatively high over time, but survival rates in these territories were lower and turnover rates were higher than in unburned or lightly burned territories.…”

Section: Pre-and Post-fire Predicted Nesting Habitat Suitabilitymentioning

confidence: 99%

The effect of scale in quantifying fire impacts on species habitats

2020

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Background: Fire size and severity have increased in the western United States in recent decades, and are expected to continue to increase with warming climate. Habitats for many species are threatened by large and high-severity fires, but the effect of spatial scale on the relationship between fires and habitat modifications is poorly understood. We used the 2011 Wallow Fire-the largest wildfire in the state history of Arizona, USA-as a case study and assessed changes in predicted nesting habitat of the threatened Mexican spotted owl (Strix occidentalis Xántus de Vésey) in the first three years following the fire. Our objective was to explore potential relationships between burn severity and changes in habitat suitability at different spatial scales. To accomplish this, we applied a multi-scale optimized habitat selection model to pre-and post-fire landscapes and compared the differences in predictions along a continuous scale gradient. Results: Fire effects on habitat quality were spatially variable and the strength and direction of relationships were scale-dependent. Spatial patterns of burn-severity mosaic resembled the patterns of habitat suitability change. High burn severity reduced nesting habitat suitability and this relationship was strongest at broad scales. Pre-fire habitat suitability was positively related to burn severity, again at fairly broad scales, but the relationship was weak. Low-severity fires had little effect on habitat suitability. Conclusions: Multi-scale analysis may influence the statistical measures of goodness of fit in assessing fire effects on species and their habitats. Future studies should explicitly address spatial scale when quantifying fire effects.

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Integrating multiple sign types to improve occupancy estimation for inconspicuous species

Goldman

Shinderman

Jeffress

et al. 2023

Ecology and Evolution

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Standard occupancy models enable unbiased estimation of occupancy by accounting for observation errors such as missed detections (false negatives) and, less commonly, incorrect detections (false positives). Occupancy models are fitted to data from repeated site visits in which surveyors record evidence of species presence. Use of indirect sign (e.g., scat, tracks) as evidence of presence can vastly improve survey efficiency for inconspicuous species but can also introduce additional sources of error. We developed a “multi‐sign” occupancy approach to model the detection process separately for unique sign types and used this method to improve estimates of occupancy dynamics for an inconspicuous species, the American pika (Ochotona princeps). We investigated how estimates of pika occupancy and environmental drivers differed under four increasingly realistic representations of the observation process: (1) perfect detection (commonly assumed for modeling pika occupancy), (2) standard occupancy model (single observation process without possibility of false detection), (3) multi‐sign with no false detections (non‐false positive model), and (4) multi‐sign with false detections (full model). For the multi‐sign occupancy models, we modeled the detection of each sign type (fresh scat, fresh haypiles, pika calls, and pika sightings) separately as a function of climatic and environmental covariates. Estimates of occupancy processes and inferences about environmental drivers were sensitive to different detection models. Simplified representations of the detection processes generally resulted in higher occupancy estimates and higher turnover rates than the full multi‐sign model. Environmental drivers also varied in their influence on occupancy models, where (e.g.) forb cover was estimated to more strongly influence occupancy in the full multi‐sign model than the simpler models. As has been reported previously in other contexts, unmodeled heterogeneity in the observation process can lead to biases in occupancy processes and uncertainty in the relationships between occupancy and environmental covariates. Overall, our multi‐sign approach to dynamic occupancy modeling, which accounts for spatio‐temporal variation in reliability among sign types, has strong potential to generate more realistic estimates of occupancy dynamics for inconspicuous species.

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Cryptic wide‐ranging movements lead to upwardly biased occupancy in a territorial species

Cited by 33 publications

References 46 publications

Megafire effects on spotted owls: elucidation of a growing threat and a response to Hanson et al. (2018)

Megafire effects on spotted owls: elucidation of a growing threat and a response to Hanson et al. (2018)

The effect of scale in quantifying fire impacts on species habitats

Integrating multiple sign types to improve occupancy estimation for inconspicuous species

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