Environmental conditions and animal behavior influence performance of solar-powered GPS-GSM transmitters

Byrne, Michael E.; Holland, Amanda E.; Bryan, A. Lawrence; Beasley, James C.

doi:10.1650/condor-16-76.1

Cited by 22 publications

(39 citation statements)

References 32 publications

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“…Previous testing indicated speed was a reliable index to whether a vulture was moving or stationary (e.g., roosting or resting; Byrne et al. ). Thus, we assumed when a GPS location reported a speed estimate of 0 km/h the vulture was not flying.…”

Section: Methodsmentioning

confidence: 99%

“…We used a variation of the model that allows movement to halt when vultures were stationary by incorporating instantaneous speed reported with GPS fixes as a stopping covariate (Johnson et al 2008). Previous testing indicated speed was a reliable index to whether a vulture was moving or stationary (e.g., roosting or resting; Byrne et al 2017). Thus, we assumed when a GPS location reported a speed estimate of 0 km/h the vulture was not flying.…”

Section: Capture and Trackingmentioning

confidence: 99%

“…However, recent advancements in solar‐powered GPS tracking technology now allow researchers to track movements of vultures at high temporal resolutions for periods >1 yr (Byrne et al. ), making such studies feasible.…”

Section: Introductionmentioning

confidence: 99%

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Using multiple data sources to investigate foraging niche partitioning in sympatric obligate avian scavengers

et al. 2019

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As carrion feeders competing for a limited and ephemeral resource, avian scavengers are ideal model organisms to study mechanisms of niche partitioning. Previous work has focused on observations of species' interactions at carcasses, and although fruitful, the inclusion of behavior beyond that at carcasses, such as movement patterns, could yield a more comprehensive understanding of mechanisms of foraging niche partitioning. Our goal was to assess how differences in physiological, morphological, and social characteristics between sympatric black vultures (Coragyps atratus) and turkey vultures (Cathartes aura) manifest interspecific variation in movement patterns, foraging habitats, and carcass use to reduce direct competition. Both species are obligate scavengers that co-occur across much of the New World. Turkey vultures are solitary foragers with enhanced olfactory capabilities and wings optimized for energy-efficient low-altitude soaring. Black vultures are aggressive, heavier bodied, and forage socially. We assessed interspecific variation in carcass exploitation using experimental carcass trials encompassing a range of habitats, carcass sizes, and seasons, and used GPS telemetry to compare how soaring conditions influenced daily space use and diurnal patterns of movement activity for each species. Turkey vultures occurred more often at small (i.e., rabbit) carcasses, and those obscured by forest cover than black vultures, and were the first vultures recorded at 94% of carcasses visited by both species. Both species increased movement rates and daily ranges when soaring conditions were favorable; however, turkey vultures had higher travel rates regardless of soaring conditions. Our results suggest the olfactory sense of turkey vultures allows them to locate smaller and visually obscured carcasses more efficiently than black vultures, facilitated by wing morphology that allows them to forage over large areas efficiently. Socially foraging black vultures appear specialized at locating larger carcasses in open habitats, which does not require as much foraging flight as turkey vultures. Our study illustrates how inclusion of movement ecology into niche partitioning studies provides a more complete understanding of the mechanisms of coexistence in avian scavenger guilds. This approach may provide important information to guide conservation efforts, such as supplemental feeding, of imperiled vulture species.

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Section: Methodsmentioning

confidence: 99%

Section: Capture and Trackingmentioning

confidence: 99%

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Using multiple data sources to investigate foraging niche partitioning in sympatric obligate avian scavengers

et al. 2019

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“…To fit the dBBMM to vulture movement paths and allow for comparisons across each model, parameters were standardized (window size = 47, margin = 11, raster = 30) with a mean location error of 23 m based on the manufacturer’s estimate [55]. Static tests revealed vertical and horizontal accuracy (mean = 4.5 m and 7.8 m, respectively) was ~80% and ~60% lower than the manufacturer’s estimate (mean = 22 m and 18 m), respectively [47]; thus, we are confident dBBMMs produced with ±23 m location error delineated reliable boundaries of actual space use.…”

Section: Methodsmentioning

confidence: 99%

Fine-scale assessment of home ranges and activity patterns for resident black vultures (Coragyps atratus) and turkey vultures (Cathartes aura)

et al. 2017

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Knowledge of black vulture (Coragyps atratus) and turkey vulture (Cathartes aura) spatial ecology is surprisingly limited despite their vital ecological roles. Fine-scale assessments of space use patterns and resource selection are particularly lacking, although development of tracking technologies has allowed data collection at finer temporal and spatial resolution. Objectives of this study were to conduct the first assessment of monthly home range and core area sizes of resident black and turkey vultures with consideration to sex, as well as elucidate differences in monthly, seasonal, and annual activity patterns based on fine-scale movement data analyses. We collected 2.8-million locations for 9 black and 9 turkey vultures from June 2013 –August 2015 using solar-powered GSM/GPS transmitters. We quantified home ranges and core areas using the dynamic Brownian bridge movement model and evaluated differences as a function of species, sex, and month. Mean monthly home ranges for turkey vultures were ~50% larger than those of black vultures, although mean core area sizes did not differ between species. Turkey vulture home ranges varied little across months, with exception to a notable reduction in space-use in May, which corresponds with timing of chick-rearing activities. Black vulture home ranges and core areas as well as turkey vulture core areas were larger in breeding season months (January–April). Comparison of space use between male and female vultures was only possible for black vultures, and space use was only slightly larger for females during breeding months (February–May). Analysis of activity patterns revealed turkey vultures spend more time in flight and switch motion states (between flight and stationary) more frequently than black vultures across temporal scales. This study reveals substantive variability in space use and activity rates between sympatric black and turkey vultures, providing insights into potential behavioral mechanisms contributing to niche differentiation between these species.

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“…Despite the high quality of tracking data, a number of factors may influence GPS location accuracy and positioning success (ratio between the observed and expected number of locations), including the effects of the terrestrial atmosphere (influencing the satellite signal), satellite constellation (influencing the number of satellites contacted), environment of the transmitters (habitat, topography, and weather), and behaviour pattern and movement intensity of the tagged animal ( Trimble Navigation Limited, 1998 ; Cargnelutti et al, 2007 ; Recio et al, 2011 ; Mattisson et al, 2016 ; Byrne et al, 2017 ). Therefore, it is crucial to assess the accuracy of GPS tracking to understand the quality of location data and how the environment and animal behaviour influence the data quality, so that the data can be exploited properly and data correction can be processed for fine-scale studies such as those of animal movements in relation to landscape ( Rempel & Rodgers, 1997 ).…”

Section: Introductionmentioning

confidence: 99%

How much can we trust GPS wildlife tracking? An assessment in semi-free-ranging Crested Ibis Nipponia nippon

Liu

Chen

Wang

et al. 2018

PeerJ

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GPS tracking has been increasingly used for wildlife studies in recent decades, but its performance has not been fully assessed, especially for newly developed lightweight transmitters. We assessed the performance of eight GPS transmitters developed in China by attaching them to Crested Ibises Nipponia nippon confined to two acclimation cages mimicking real habitats. We calculated the distance between GPS locations and the centroid of the cages as the positioning error, and used the 95% (95th percentile) positioning errors to define the accuracy. The positioning success averaged 92.0%, which is much higher than that of previous studies. Locations were not evenly distributed by Location Class (LC), with the LC A and B locations accounting for 88.7%. The observed 95% positioning error in the locations of LC A (9–39 m) and B (11–41 m) was quite accurate, while up to 6.9–8.8% of poor-quality locations were detected in LC C and D with >100 m or even >1, 000 m positioning error. Positioning success and accuracy were different between the test sites, probably due to the difference in vegetation structure. Thus, we argue that the tested transmitters could provide a large proportion of high-quality data for fine-scale studies, and a number of poor-quality locations that need attention. We suggest that the HPOD (horizontal dilution of precision) or PDOP (positional dilution of precision) be reported instead of the LC as a measurement of location accuracy for each location to ensure identification and filtering of implausible locations.

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Environmental conditions and animal behavior influence performance of solar-powered GPS-GSM transmitters

Abstract: BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.

Cited by 22 publications

References 32 publications

Using multiple data sources to investigate foraging niche partitioning in sympatric obligate avian scavengers

Using multiple data sources to investigate foraging niche partitioning in sympatric obligate avian scavengers

Fine-scale assessment of home ranges and activity patterns for resident black vultures (Coragyps atratus) and turkey vultures (Cathartes aura)

How much can we trust GPS wildlife tracking? An assessment in semi-free-ranging Crested Ibis Nipponia nippon

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