The scaling of motion: dynamic body acceleration declines with body mass in black-tailed prairie dogs

Abstract

Dynamic body acceleration (DBA) derived from animal-borne accelerometers is widely used to infer behaviour and movement-related energetic expenditure, yet its interpretation in comparative contexts may be complicated by body size. Biomechanical scaling predicts that smaller animals and individuals may generate higher mass-specific accelerations during locomotion, but this expectation has rarely been tested within a free-ranging species. We deployed collar-mounted tri-axial accelerometers at 40 Hz on 41 free-ranging black-tailed prairie dogs ( Cynomys ludovicianus ) using a standardised attachment protocol and quantified movement intensity using smoothed vectorial dynamic body acceleration (sVeDBA). In a log-log scaling analysis in which sVeDBA was natural-log transformed at the record level before averaging within individuals, mean log-sVeDBA declined with increasing body mass ( \(\:b=-1.37\) , 95% CI −2.33 to − 0.41; \(\:{R}^{2}=0.175\) ). Across the observed body-mass range of 0.82–1.31 kg, fitted geometric mean sVeDBA was 47.3% lower at the maximum than at the minimum body mass, although uncertainty around this estimate was substantial (95% CI 17.3–66.4% lower). Behavioural classification informed by video-synchronised captive observations indicated that daytime resting allocation increased with body mass, whereas estimated changes in walking/foraging and running allocation were negative but uncertain. Accounting for daytime walking/foraging and running allocation attenuated the estimated mass coefficient by approximately 24%, but the negative mass–sVeDBA relationship remained evident. Behaviour-specific relationships differed among resting, walking/foraging and running, indicating that the whole-deployment pattern did not reflect a uniform scaling of locomotor acceleration. Our results provide field-based evidence that body mass can influence accelerometer-derived movement summaries within a species and highlight the importance of interpreting DBA alongside behaviour, morphology and attachment context in comparative or energetic applications.