Spatiotemporal Patterns of the California Spotted Owl’s Territorial Vocalizations

Klinck

Gustafson

et al. 2020

Conservation Biology

Self Cite

Recent bioacoustic advances have facilitated large‐scale population monitoring for acoustically active species. Animal sounds, however, can of information that is underutilized in typical approaches to passive acoustic monitoring (PAM) that treat sounds simply as detections. We developed 3 methods of extracting additional ecological detail from acoustic data that are applicable to a broad range of acoustically active species. We conducted landscape‐scale passive acoustic surveys of a declining owl species and an invasive congeneric competitor in California. We then used sex‐specific vocalization frequency to inform multistate occupancy models; call rates at occupied sites to characterize interactions with interspecific competitors and assess habitat quality; and a flexible multivariate approach to differentiate individuals based on vocal characteristics. The multistate occupancy models yielded novel estimates of breeding status occupancy rates that were more robust to false detections and captured known habitat associations more consistently than single‐state occupancy models agnostic to sex. Call rate was related to the presence of a competitor but not habitat quality and thus could constitute a useful behavioral metric for interactions that are challenging to detect in an occupancy framework. Quantifying multivariate distance between groups of vocalizations provided a novel quantitative means of discriminating individuals with ≥20 vocalizations and a flexible tool for balancing type I and II errors. Therefore, it appears possible to estimate site turnover and demographic rates, rather than just occupancy metrics, in PAM programs. Our methods can be applied individually or in concert and are likely generalizable to many acoustically active species. As such, they are opportunities to improve inferences from PAM data and thus benefit conservation.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Using the ecological significance of animal vocalizations to improve inference in acoustic monitoring programs

Klinck

Gustafson

et al. 2020

Conservation Biology

Self Cite

“…This suggests that CSO is less vocally active when foraging. This is corroborated by the finding that bouts of CSO territorial calling are shorter and contain fewer vocalizations in montane riparian forest, which is the key habitat of flying squirrels, one of their primary prey species (Wood, Schmidt, et al, 2019). Foraging habitat selection itself was also surprising:…”

Section: Discussionmentioning

confidence: 85%

Density dependence influences competition and hybridization at an invasion front

Diversity and Distributions

Kryshak

Gustafson

et al. 2021

Self Cite

“…For example, evidence suggests that owls face trade‐offs when vocalizing during foraging. Spotted owls appear to reduce vocal activity in the preferred habitat of flying squirrels, a key prey species, possibly to mitigate prey vigilance (Wood et al 2019 c ). In contrast, our data revealed that mated pairs of spotted owls employed and responded to vocal signals while foraging.…”

Section: Acoustic Ecologymentioning

confidence: 99%

“…For example, if spatial patterns in prey capture and delivery studies can be connected with stable isotope values, and if stable isotope analyses are conducted across a larger population, the results could be extended to entire landscapes (Hobart et al 2019). Acoustic tag results could be used to inform studies that draw on landscape‐scale passive acoustic survey data to study animal behavior (Wood et al 2019 c ) and interspecific interactions (Wood et al 2019 a ). The combinations of emerging technologies and methods that we have described here have the potential to resolve long‐standing mysteries in owl ecology.…”

Section: Conclusion and Emerging Frontiersmentioning

confidence: 99%

Illuminating the Nocturnal Habits of Owls with Emerging Tagging Technologies

Wildlife Society Bulletin

Zulla

Whitmore

et al. 2021

Self Cite

Owls play important cultural, ecological, and indicator roles throughout the world. Yet owls’ cryptic behavior has led to uncertainties about their basic ecology, including foraging, communication, and functional roles within the community, and potentially hindered the implementation of effective conservation measures. Here we demonstrate the potential for next‐generation GPS tags capable of recording high‐precision, minute‐by‐minute locations paired with other technologies to resolve some of these uncertainties. We combined high‐precision GPS tagging data with infrared (IR) video recorded by arboreally‐mounted cameras at 5 spotted owl (Strix occidentalis) nest sites in the Sierra Nevada, USA to provide a uniquely detailed examination of owl foraging patterns. Our approach allowed us to identify the precise time and location of 54 predation events and prey identity. We also used high‐precision GPS tags with on‐board audio recorders to map the vocal activity of 8 individuals by matching the time of vocalizations in the audio data to GPS locations recorded at one‐minute intervals. The combined spatial and acoustic data revealed that nonbreeding males had the most widespread territorial vocal activity (i.e., producing 4‐note territorial calls), while females provisioning fledglings displayed extensive nonterritorial vocal activity (i.e., producing many contact calls). Thus, the GPS‐tag technologies we employed can provide opportunities to better understand owl foraging, communication, territoriality, and population dynamics. The methods we describe are time‐ and resource‐intensive but can be paired with techniques that are more applicable at landscape scales, such as stable isotope analyses, LiDAR‐based habitat analyses, and passive acoustic monitoring to link local processes to broad‐scale ecological patterns. Therefore, our approach could be applied to many species whose behavior inhibits direct observation. © 2021 The Wildlife Society.