A standardised framework for analysing animal detections from automated tracking arrays

Abstract

Background: Over the past 15 years, the integration of localised passive telemetry networks into centralised data repositories has greatly enhanced our ability to monitor the presence and movements of highly mobile and migratory species. These large-scale networks are now generating big data, allowing meta-analyses across multiple species, locations, and temporal scales. Broad-scale comparisons of animal movement metrics are constrained by the use of diverse analytical techniques among researchers. Accordingly, there is a need for a tool-set to assist in calculating animal movement metrics that can be easily applied to datasets from local studies to large-scale cooperative networks. Results: We present a standardised framework and an associated analysis tool-set that facilitates the calculation of a range of activity space and movement metrics for passive telemetry datasets. Application of the tool-set is demonstrated using data from the Integrated Marine Observing System continental-scale network of underwater acoustic receivers. We show how the metrics can: (1) be directly compared among multiple species monitored at multiple sites; (2) be compared among multiple species tagged at a single study site; and (3) assess changes in activity space metrics over time. Conclusions: Establishing a framework and tool-set to analyse data from large-scale networks progresses the field of passive telemetry beyond the traditional individual-, species-, or location-centric approaches to facilitate national-or international-scale outputs that better address important questions in the field of movement ecology.

Sex-based differences in movement and space use of the blacktip reef shark, Carcharhinus melanopterus

“…COA estimates were calculated for each individual using a customised R script [75] and represented the mean position of each shark over a 30-minute time step weighted by the number of detections at each receiver. COA positions were calculated prior to estimating KUDs to account for the inherent spatio-temporal autocorrelation within the data structure, and account for varying transmission settings among different models of acoustic transmitters used in the study [76]. The adehabitatHR package in R [77] was used to calculate monthly space use using 50 and 95% KUDs.…”

“…Variance inflation factors were calculated using the R package car [80] to test models for multicollinearity. Graphs were produced using the 'Animal Tracking Toolbox' within the VTrack package [76]. The 'dredge' function in the MuMIn package in R [81] was used to generate a series of candidate additive models for 50 and 95% KUDs that represented every possible combination of fixed (size, sex and month) and random (individual) factors (global model:…”

Shark movements in the Revillagigedo Archipelago and connectivity with the Eastern Tropical Pacific

“…The ATT library (37) was used to calculate the Center of Activity (COA) and heatmaps. The following libraries of R were used to create maps: ggmap, osmdata and wesanderson (for color palette).…”

Animal-Borne Telemetry: An Integral Component of the Ocean Observing Toolkit

“…These large data sets provide challenges in data management and analysis, especially when considering that these data are typically used to calculate movement metrics, such as home range size. Standardized approaches that calculate metrics of detection, dispersal and activity space allow direct comparisons among sites Udyawer et al (2018). Integration of multiple data streams, such as environmental variables, to help interpret movements and space-use, also enhance the value of telemetry data but present new analytical and data management challenges (see below).…”