What acceleration data from wildlife collars and animal body mass tell us about seed dispersal

Abstract

Abstract Background: Animals are very important for plant seed dispersal in light of global change. The study of seeds transport on the exterior of animals’ bodies (epizoochory) is particularly challenging due to the difficulty to describe and quantify the process of seed release. Shaking movement of fur has been shown to cause seed release and can hence determine seed retention times, necessary to assess dispersal distances. Such information on shaking movements is, however, only available on the neck of animals thanks to wildlife collars containing accelerometers. Methods: In order to quantify shaking forces on the main body of mammals where most plant seeds attach, and to predict this body acceleration from (known) neck acceleration, we simultaneously measured acceleration at the neck, the breast and the upper hind leg of mammals spanning a large range of body masses. We quantify shaking strength as the 95%-quantile of the resultant acceleration (of all measured values in data subsections of five seconds). Results: While, compared to the neck, acceleration had a similar range of values at the breast and was considerably higher at the leg, neck acceleration in combination with animal body mass proved to be a very valuable predictor: 81 and 63% of variation in breast and leg acceleration could be explained, respectively. Conclusions: These results enable the use of available acceleration data from animals’ necks to predict body acceleration for mammals with known body mass. In combination with i) further lab experiments to determine seed release in dependence of fur acceleration for specific seed-fur combinations, and ii) animal movement data, this information can be used to predict probability and spatial distributions of seed dispersal. Besides seed dispersal, we believe that the ability to predict body acceleration on mammals should also benefit other ecological fields like parasitology.