ProxLogs: Miniaturised proximity loggers for monitoring association behaviour in small animals
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Evolutionary Ecology, Universiteit Antwerpen
Faculty of Applied Engineering, Universiteit Antwerpen
imec, Antwerp, Belgium
Pest Management Centre, Sokoine University of Agriculture
Behavioural Ecology and Ecophysiology, Universiteit Antwerpen
Lucinda Kirkpatrick   

Evolutionary Ecology, Universiteit Antwerpen
Online publication date: 2021-08-19
Publication date: 2021-08-19
Hystrix It. J. Mamm. 2021;32(2):165–175
Logging data and the R code used to download and manipulate the data will be made available as example data for R functions / R package to manipulate logger data.
The ability to monitor associations between wild animals is essential for understanding the processes governing gene transfer, information transfer, competition, predation and disease transmission. Until recently, such insights have been confined to large, visible or captive animals. However, the rapid development of miniature sensors for consumer electronics is allowing ecologists to monitor the natural world in ways previously considered impossible. Here we describe miniature (<1 g) proximity loggers we have developed that use Bluetooth Low Energy transmission to register contacts between individuals. Our loggers are open source, low cost, rechargeable, able to store up to 2000 contacts, can be programmed in situ and can download data remotely or through a mobile phone application, increasing their utility in remote areas or with species which are challenging to recapture. We successfully trialled our loggers in a range of field realistic conditions, demonstrating that Bluetooth Low Energy is capable of logging associations in structurally complex habitats, and that changes in received signal strength can be equated to short range changes in distance between loggers. Furthermore, we tested the system on captive European starlings (Sturnus vulgaris) and captive multimammate mice (Mastomys natalensis). The ability to include other sensors is retained in our prototypes, allowing for the potential integration of physiological and behavioural inference into social networks derived from our approach. Due to its open source nature, small size, flexibility of use and the active research currently being undertaken with Bluetooth Low Energy, our approach is a valuable addition to the biologging toolkit.
BLE Bluetooth Low Energy - Low energy form of Bluetooth wireless communication. Supported as standard by most mobile and computing operating systems.
RSSI Received Signal Strength Indicator - Estimate of the power that a radio frequency device is receiving from another device. Can be broadly equated to changes in distance, with the RSSI decreasing as distance between devices increases.
LoRa Long Range - Proprietary low power wide area network modulation technique. Enables long range transmission with low power consumption, but lacks accuracy over smaller ranges.
NB-IoT Narrow Band Internet of Things - Low power wide area network radio technology standard. Concentrates on low power, low cost indoor localisation.
BATS Broadly Applicable Tracking System - Low power, wide band network developed by Ripperger and colleagues. Proximity detection is carried out using BLE, additional spatial localisation and long range downloading possible.
GPS Global Positioning System - Satellite based radionavigation system that provides geolocation and timestamp data to specific devices. Needs a consistent signal to at least 4 satellites for accurate positioning, and is not low power.
RFID Radio Frequency Identification - Passive system that uses electromagnetic fields at a reader that are triggered by the logger to register a contact. No battery is required on the animal as the tag is passive. The range at which a tag can activate the reader are relatively limited (~60 cm or less).
We thank Christine Talmage, Geoff Sabuni and Shabani Lutea for their help during fieldwork in Tanzania, and Dragan Subotic and Kwinten Schram for help during system development. We thank Geert Eens, Peter Scheys and Frank Adriaensen for assistance with carrying out the starling and multimammate mouse experiment. We also thank the reviewers and editors for helpful comments that improved the manuscript.
This research was funded with a Global Minds Small Research Grant (GMKP0101). LK is a Junior Fellow with the Fonds-Wetenschappelijk-Onderzoek (FWO Research Foundation) which has co-financed this work (Grant nos: 1220820N and 1513519N).