Acoustic telemetry is a common methodology in the study of animal movement, behaviour, and physiology in aquatic environments. In the marine environment, receiver performance is limited by environmental conditions and habitat (which modulate receiver detection range) and the number of tagged animals in the system (with signal collisions reducing the receiver’s ability to decode unique transmitter IDs). The Innovasea NexTrak receiver was developed to address the key challenges of detection range, number of transmissions successfully decoded, and quality of detection data. To assess how NexTrak receivers perform relative to the commonly used VR2AR receiver, we co-deployed NexTrak and VR2AR receivers on six moorings within a larger acoustic array deployed to study white shark movement ecology in Mahone Bay, Nova Scotia, Canada. We compared receiver performance in terms of (i) number of animals detected, (ii) number of transmissions received, (iii) structure and duration of detection events, and (iv) the effects of environmental noise on detection rates. Results showed 27.7 ± 14.4% more white sharks and 86.0 ± 20.9% more detections for NexTrak relative to VR2AR. At the detection-event level, NexTrak recorded more detections (3.9 ± 3.6, range: 0–19) than VR2AR (2.2 ± 3.0, range: 0–11). Detection events were also longer for NexTrak (471 ± 321 s, range: 0–1549 s) than for VR2AR (324 ± 241 s, range: 0–893 s), equating to a 45% higher detection-event duration as a proxy for increased detection range. While noise was a significant predictor of hourly detections, with each mV increase associated with a ~ 0.4% reduction in detections, there was no discernable difference between NexTrak and VR2AR in their performance relative to noise in our relatively quiet study system. Overall, it is evident that the NexTrak receiver has the potential to improve acoustic telemetry capabilities though enhanced detection efficiency and data quality relative to VR2AR. Improvements in detection range and decoding efficiency have implications for research costs, array design decisions, and the accuracy and precision of continuous movement tracks in fine-scale positioning arrays.

Habitats are heterogeneously distributed across landscapes, and animals move through them to access different resources, resulting in energetic consequences. In the Laurentian Great Lakes, nearshore areas provide important habitat for the majority of fish species; however, differences in the distribution and composition of physical (e.g., vegetation, depth, fetch, and substrate type/size and temperature) habitat attributes create habitat heterogeneity. We used high-resolution acoustic telemetry data combined with acceleration sensors to test how spatial and temporal factors relate to acceleration of two ecologically and economically important fish species, Largemouth Bass (Micropterus nigricans) and Northern Pike (Esox lucius), within a system of coastal embayments in Toronto Harbour, Lake Ontario. For both species, we found that sites characterized by higher vegetation cover, shallower depths, and decreased fetch (i.e., coastal vegetated and wetland sites) were associated with lower acceleration values. We also identified several areas within Toronto Harbour that likely serve as important movement corridors between higher suitability sites. Temporal variation of acceleration was significant for both species and was influenced by season and diel period. Both Largemouth Bass and Northern Pike exhibited increased acceleration during spring and summer. Both species exhibited peak acceleration at dawn and dusk. The use of accelerometers was instrumental in identifying important habitats, movement corridors, and elucidating temporal trends across seasons and diel periods. Our results highlight the importance of incorporating habitat connectivity between habitat patches used for different purposes into conservation and restoration planning.

Over the last six decades, the biologging research community has reduced instrument effects on study animals by miniaturizing devices, employing sophisticated release mechanisms, and developing other novel technological advancements. However, biologging devices can still impact animal physiology, behavior, and demography—the very biological metrics the instruments are meant to measure. Recent meta-analyses have emphasized the subjectivity of field-wide “rules of thumb” such as the 3% rule, but opportunities to quantify effects more objectively can be expensive or impossible to implement when instrumenting new species. There is therefore a time-sensitive need for systematic reporting of biologging instrument characteristics based on known effects to animal welfare and data quality. We used 202 biologging impact studies from the last thirty years to draw broad, multispecies connections between instrument characteristics and animal physiology, behavior, and/or demography. We build on impact studies that focus on a single species, instrument type, or attachment method to offer solutions applicable across those taxa, technologies, and methodologies. From the literature, we distilled eight best practices for biologging researchers with a particular focus on minimum reporting standards as a low-cost, high-impact way to promote animal welfare and data quality. We propose a preliminary minimum reporting standard, informed by the literature and presented as a machine-readable checklist, that biologging researchers can include with their manuscripts or data submissions to provide data for future meta-analyses. We also present an example of a completed checklist to demonstrate the feasibility of such a standard and a plan for community input and adoption via the International Bio-Logging Society. Robust biologging infrastructure, beginning with a minimum reporting standard informed by the literature on instrument impacts, will facilitate the expansion of biologging across the globe and across disciplines while ensuring animal welfare and improving data quality. As biologging instruments become less expensive and more accessible, researchers, journals, and funders are better positioned than ever to broaden and implement these standards.Supplementary InformationThe online version contains supplementary material available at 10.1186/s40317-025-00438-w.

Automated radio telemetry systems (ARTS) consisting of animal-borne radio transmitters and networks of fixed radio receivers are frequently used to continuously track wildlife movements over time. The low weight of available radio transmitters and the ability of these systems to collect data with high temporal resolution make ARTS an attractive alternative to other wildlife tracking technologies. However, the research questions that can be addressed with ARTS are often limited by the spatial accuracy of location data produced by the system. One of the primary methods used to produce location estimates with ARTS involves comparing the received signal strength (RSS) of radio transmissions detected by multiple receivers in a network. The accuracy of the resulting locations is highly dependent on the algorithm used to process the raw RSS data generated by the ARTS into location estimates. In this work, we have developed a grid search algorithm for producing location estimates from RSS data generated by networks of receivers. In an experiment conducted with a radio transmitter and receiver network, we demonstrate that the grid search method produces location estimates that are greater than 2 times more accurate than the commonly used method of multilateration. A simulation was developed to compare the accuracy of the two methods over a large range of receiver spacings and with varying levels of measurement noise in the system. The simulation showed that the grid search method and multilateration perform similarly for receiver networks with relatively close receivers; however, as the distance between receivers in the array increases, the mean error of location estimates increases much more rapidly for multilateration than for grid search. The improvement in spatial accuracy realized through the use of grid search enables the design of wildlife tracking studies utilizing ARTS to address research questions that were previously inaccessible.

BackgroundPassive acoustic telemetry is a common tool used to study fish movements. Range tests, or determining the distance at which transmitters can be recognized by a receiver, are needed to accurately determine fish position in the environment. However, range tests are not often conducted or are only completed during a single season prior to an acoustic telemetry study commencing though seasonality may affect detection probabilities over a multi-year study’s duration. Therefore, we conducted a series of tests to assess the effect of seasonality on range detection over a 3-year period on Lewis and Clark Lake, a Missouri River reservoir. Specifically, we measured the effects that seasonal environmental (e.g., wind, depth, temperature) factors had on detection probability at a range of distances using Innovasea V13 acoustic transmitters at 14 VR2tx 69-kHz passive receivers. These data were used to inform array design for a concurrent acoustic telemetry research project. We accounted for spatiotemporal variation in detection probability by evaluating monthly detection probabilities across years from March–September during 2022–2024.ResultsMean detection probability for Lewis and Clark Lake receivers from range tests was 0. 60 for 50 m, 0.50 for 100 m, 0.37 for 200 m, 0.23 for 400 m, 0.15 for 600 m, and 0.11 for 800 m. We found detection probabilities in the spring were greater than those in the other seasons. We found negative relationships between detection probabilities and distance between the tag and receiver, wind speed, inflow through Fort Randall Dam, and tag depth. Further, we found detection probabilities varied with river kilometer, presumably due to habitat differences.ConclusionsImplications of our findings include consideration of lower realized detection probabilities (i.e., resulting from environmental factors) compared to equipment capabilities during study design, and the consideration of both anthropogenic influences (i.e., inflow) and natural environmental factors (i.e., wind) that affect detection probabilities. The receiver array in Lewis and Clark Lake, South Dakota was modified due to the findings presented herein, in that receivers were stationed in nearshore locations presumably sheltered from the wind. In general, our data support placing receiver stations nearer to shore and protected from wind fetch to the best extent possible to optimize detection distance.

BackgroundResearching the movement patterns of fossorial animals and mapping of burrow systems presents a significant challenge due to the difficulty of direct observation and the limitations of most tracking systems to collect location fixes underground. A potential solution is using archival tags combined with dead-reckoning, a technique employed in nautical navigation to track animal movement underwater and through dense vegetation. However, this method has not yet been applied to the mapping of complex burrow systems in fossorial species. This study aims to test this approach using accelerometers and magnetometers attached to collars on black-tailed prairie dogs (Cynomys ludovicianus) The goal was to determine if 2D dead-reckoning, based on vectors derived from speed and heading data, could accurately track prairie dog movements and, by extension, map the structure of their burrows. To evaluate this method, we deployed 12 tags on wild animals and recorded acceleration and magnetometer data at 40 Hz and 16 Hz, respectively. These animals were allowed to move through artificial burrows comprised of plastic tubes of defined shape, before being released into the wild and tracked. The “tube runs” were used to validate 2D dead reckoning trajectory estimation. We compared the accuracy of five techniques for deriving speed: vectorial dynamic body acceleration (VeDBA), vectorial static body acceleration (VeSBA), step count, and constant speed.ResultsAcceleration signals reliably indicated traveling behavior. Among the methods tested, the Vectorial sum of Dynamic Body Acceleration (VeDBA) proved to be the most accurate proxy for speed, with the smallest mean error (Fig. 5). Speed coefficients for VeDBA varied between runs (0.009 to 0.042) with this variation being the result of individual differences The animals moved at speeds ranging from 0.01 to 1.42 m/s. In addition, the 2D dead-reckoning process documented all turns (100%) in our plastic tunnel system and had a mean error of 15.38 cm over all test tunnel lengths of up to 4 m. This highlighted the potential for representing animal movements and the layout of burrows in free-roaming prairie dogs. We also determined that use of acceleration metrics identified 22 of 24 times (92%) when collared animals exited their burrows but only 4 or 6 times (67%) when they entered them.ConclusionsThis work highlights the importance of dead-reckoning in studying space use by fossorial animals, essential for understanding how they interact with their environment, including vegetation and topography. Beyond environmental context, analyzing the specifics of animal movement—such as path tortuosity, speed, step lengths, and turn angles—is crucial for insights into species diffusion, foraging strategies, and vigilance.

BackgroundThere is considerable interest in the suitability of the farm-flock Katahdin hair sheep breed for large-scale extensive range sheep production systems. Flocking behavior or “flockability”, a measure of gregariousness, is critical for sheep to produce in extensive, herded management systems. An evaluation of the Katahdin breed in a Western U.S. range environment compared to the traditional range-adapted Rambouillet breed is underway. The objective was to compare the flockability of range-reared Katahdin ewes to Rambouillet ewes during the summer grazing season using GPS collars. Flockability was measured by how far a ewe was dispersed from the centroid of the study flock and the total daily distance traveled compared to the study flock.ResultsComplete GPS coordinates were available from 23 Rambouillet and 29 Katahdin ewes in 2023 and five Rambouillet and five Katahdin ewes in 2024. Study groups were managed in bands of 800–1,000 ewes with lambs. During the day, the Katahdin breed had a farther dispersion from the study flock centroid for one of the study groups (P < 0.05), the Rambouillet breed was more dispersed for one study group (P < 0.05), and the breeds did not differ for one study group (P > 0.05). The effect size, measured using Cohen’s d, was small for all groups. The daily distance traveled was farther for the Rambouillet breed in two study groups (P < 0.05) when compared to the Katahdin breed, but did not differ for the other study group (P > 0.05). The effect size was low regardless of significance. When individual ewes were compared, both breeds had ewes that were either closer or farther away from the flock centroid (P < 0.05) or ewes that traveled farther or shorter daily distance (P < 0.05).ConclusionsThe Katahdin breed was similar in flockability to the traditional, range-adapted Rambouillet breed, indicating that the Katahdin breed is well suited for grazing in an extensive range environment. This study indicates the Katahdin breed exhibits favorable behavioral characteristics to flock well in large-scale extensive range systems and provides an opportunity for Western U.S. producers interested in incorporating this breed into their flock.

Biologging studies rely on the assumption that equipped animal behaviours are representative of the ones displayed by unequipped individuals. Identifying any tagging effects is therefore necessary to correctly interpret recorded data from equipped animals. The majority of seabird studies report an absence of tag effects using broad metrics such as breeding success or foraging trip duration. However, animals may compensate for tag attachment through increased effort or behavioural responses. We compared foraging trip and dive characteristics of 42 breeding Manx shearwaters (Puffinus puffinus) equipped with a range of biologging tags representing 0.9–3.7% body mass. There was no evidence that increasing tag weight affected foraging trip duration, but individuals equipped with heavier tags travelled shorter distances and at slower speed as well as spending more time in Area Restricted Search behaviour. The number of dives performed per hour of foraging trip was not affected by increasing tag weight, but individuals with the heaviest tags conducted shorter and shallower dives with slower ascent rates than those equipped with lighter tags. Additionally, birds equipped with the heaviest tags increased resting time between dives, suggesting a need to recover from a greater physiological cost of diving when equipped. Our study is one of the few that describe acute tagging impacts on seabird diving behaviour and foraging effort, suggesting that deployments should be kept as short as possible to limit cumulative impacts.