Animal lifestyle affects acceptable mass limits for attached tags

by Rory P. Wilson, Kayleigh A. Rose, Richard M. Gunner, Mark D. Holton, Carlos M. Duarte,
Research article Year: 2021 DOI:


Wilson, R. P., Rose, K. A., Gunner, R., Holton, M. D., Marks, N. J., Bennett, N. C., Duarte, C.M.,... & Scantlebury, D. M. (2021). Animal lifestyle affects acceptable mass limits for attached tags. Proceedings of the Royal Society B288(1961), 20212005.


Animal-attached devices have transformed our understanding of vertebrate ecology. To minimize any associated harm, researchers have long advocated that tag masses should not exceed 3% of carrier body mass. However, this ignores tag forces resulting from animal movement. Using data from collar-attached accelerometers on 10 diverse free-ranging terrestrial species from koalas to cheetahs, we detail a tag-based acceleration method to clarify acceptable tag mass limits. We quantify animal athleticism in terms of fractions of animal movement time devoted to different collar-recorded accelerations and convert those accelerations to forces (acceleration × tag mass) to allow derivation of any defined force limits for specified fractions of any animal's active time. Specifying that tags should exert forces that are less than 3% of the gravitational force exerted on the animal's body for 95% of the time led to corrected tag masses that should constitute between 1.6% and 2.98% of carrier mass, depending on athleticism. Strikingly, in four carnivore species encompassing two orders of magnitude in mass (ca 2–200 kg), forces exerted by ‘3%' tags were equivalent to 4–19% of carrier body mass during moving, with a maximum of 54% in a hunting cheetah. This fundamentally changes how acceptable tag mass limits should be determined by ethics bodies, irrespective of the force and time limits specified.