Hares (Lepus spp.) as seed dispersers of Retama raetam (Fabaceae) in a sandy landscape

Hares in the sandy ecosystem of the Mediterranean coastal plain in Israel consume pods of the widespread desert plant Retama raetam. The aim of this study was to explore some of its qualities as a dispersal agent of such an important component of the vegetation of Mediterranean arid habitats. Although the pericarp acts as the nutritious 'reward', the hares do not select the most profitable pods with the highest pericarp/seed mass ratio. Of the 718 randomly collected hare pellets 43% contained H. raetam seeds. More than half (55%) of those containing seeds had only one seed, 43% contained two to three seeds and the other 2% contained four to five seeds. Seeds from hare pellets imbibed water more slowly than either exposed seeds which were collected from the sand surface, or manually scarified seeds, but faster than intact seeds which were removed from pods. Untreated seeds from pods had low germination (6%), but most were alive, as indicated by high (70%) germination when scarified. While only 6% of seeds obtained from hare pellets germinated, 44% of them germinated after scarification. Thus, hares did not have a lethal effect on seed viability. It should be emphasized that the difference between these two values (38%) is added to the soil seed bank as 'exposed seeds'. The height and growth rate of seedlings that emerged from hare pellets in pots did not differ from those of seedlings receiving other treatments. Hence, the hypothesis that seedlings in pellets may be favoured by the nutrient pool available to them was not confirmed. We conclude that hares have the potential to act as a legitimate dispersal agent for R. raetam, especially as a carrier of seeds away from the parent plant. (C) 1997 Academic Press Limited.