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A general scaling law reveals why the largest animals are not the fastest


Speed is the fundamental constraint on animal movement, yet there is no general consensus on the determinants of maximum speed itself. Here, we provide a general scaling model of maximum speed with body mass, which holds across locomotion modes, ecosystem types and taxonomic groups. In contrast to traditional power-law scaling, we predict a hump-shaped relationship resulting from a finite acceleration time for animals, which explains why the largest animals are not the fastest. This model is strongly supported by extensive empirical data (474 species, with body masses ranging from 30 μg to 100 tonnes) from terrestrial as well as aquatic ecosystems. Our approach unravels a fundamental constraint on the upper limit of animal movement, thus enabling a better understanding of realized movement patterns in nature and their multifold ecological consequences.

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Figure 1: Concept of time-dependent and mass-dependent realized maximum speed of animals.
Figure 2: Empirical data and time-dependent model fit for the allometric scaling of maximum speed.
Figure 3: Effect of thermoregulation on the maximum speed of animals.
Figure 4: Predicting the maximum speed of extinct species with the time-dependent model.

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M.R.H., W.J., B.C.R. and U.B. acknowledge the support of the German Centre for integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig funded by the German Research Foundation (FZT 118).

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Authors and Affiliations



M.R.H. and U.B. developed the model. M.R.H. gathered the data. M.R.H. and B.C.R. carried out statistical analyses. W.J. was involved in study concept and data analyses. M.R.H. and U.B. wrote the paper. All authors discussed the results and commented on the manuscript.

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Correspondence to Myriam R. Hirt.

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The authors declare no competing financial interests.

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Supplementary information

Supplementary Tables 1–5; maximum speed database

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Hirt, M.R., Jetz, W., Rall, B.C. et al. A general scaling law reveals why the largest animals are not the fastest. Nat Ecol Evol 1, 1116–1122 (2017).

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