Human and animal behavior exhibits power law correlations whose origin is controversial. In this work, the spontaneous motion of laboratory rodents was recorded during several days. It is found that animal motion is scale-free and that the scaling is introduced by the inactivity pauses both by its length as well as by its specific ordering. Furthermore, the scaling is also demonstrable in the rates of event's occurrence. A comparison with related results in humans is made and candidate models are discussed to provide clues for the origin of such dynamics. © 2009 American Institute of Physics. ͓DOI: 10.1063/1.3211189͔ Recent findings of heavy tailed distributions in the patterns of human activity reemphasized our poor understanding on the mechanisms responsible for such type of dynamics. To shed light on the most significant features of these fluctuations, the problem is here oversimplified by studying a much elementary system: the spontaneous motion of rodents recorded during several days. The analysis of the animal motion reveals a robust scaling not only in univariate distributions, comparable with the results previously reported in humans, but also in its correlation structure. It is shown that the most relevant features of the experimental results can be replicated by the statistics of the activation-threshold model proposed in another context by Davidsen and Schuster. It constitutes an alternative mechanism to queuing, cascading, and nonhomogeneous processes, currently contemplated as candidates to account for the statistics of diverse human activities, but that seem not suitable for motion patterns.