Experiments on adhesive dispersal by wood mouse: seed shadows and dispersal distances of 13 plant species from cultivated areas in southern Sweden

This study on epizoochory offers experimental data on retention times and potential dispersal distances of propagules of 13 plant species that commonly inhabit cultivated areas in the south of Sweden. Wood mouse Apodemus flavicollis was used as dispersal vector. Seven of the investigated species produce fruits that carry obvious hooks, barbs or bristles and for comparison the remaining six species, lacking such features, were also included. Excised fruits that initially carried appendages were used in a complementary comparison. Propagules were applied by hand to the back of the animals, which were then released in enclosures to move about freely. Observations were made continually until the seeds were dropped. The distance covered by the animals while moving was measured and the potential dispersal distances calculated. Small fruits were in general found to be more efficiently transported than large ones, but large propagules carrying appendages sometimes remained in place for considerable periods. The potential dispersal distances ranged up to nearly 30 m. The retention time was significantly enhanced by the presence of dispersal attributes. The behavioural pattern of the animals (grooming, movements) plays a significant part in the successful transportation of propagules. By comparing the result with similar experiments using fallow deer Dama dama and domestic cattle Bos taurus as dispersal vectors it can be stated that mice are surprisingly effective as seed dispersers. Large mammals disperse propagules on a larger scale (<1 km) compared with small mammals, that affect plant distribution more locally (<100 m). We consider adhesive dispersal a most significant component in plant metapopulation dynamics, considerably enhancing the probability of occasional propagules reaching suitable sites in a fragmented landscape.