1 research outputs found
Are you strong enough to carry that seed? Seed size/body size ratios influence seed choices by rodents
7 pages 8 figuresGranivorous rodents prefer large seeds because they offer a higher nutrient content, but such preferences
may be counterbalanced by the higher costs of handling and transporting larger seeds. We hypothesized
that this compromise underlying foraging decisions depends simultaneously on the size of both seeds and
rodents. A given seed offers a fixed amount of resources, but the costs of handling and transporting that
seed could increase as the rodent size decreases. We designed a laboratory experiment to assess explicitly
whether seed choices depend on the size of both seeds and rodents. As a model, we used two different-sized
species, the Algerian mouse Mus spretus (8e15 g) and the wood mouse Apodemus sylvaticus (18e40 g), that
face the decision of choosing Holm oak (Quercus ilex) acorns from 0.5 to 15 g under natural conditions. The
probability of seed removal decreased as the ratio of seed size to rodent size increased in both rodent species.
Seeds heavier than 60% of the rodent’s mass led to substantial decreases in acorn removal and seeds
heavier than 70% of the rodent’s mass were in no case removed. This critical value limited the choice of the
largest seeds by the smaller species, but not by the larger one. Therefore, the larger species selected larger
acorns and with a wider variance in size than the smaller species. Our results show the importance of considering
jointly the sizes of seeds and rodents in the study of foraging decisions and seed dispersal behaviour
by granivorous rodents.Peer reviewe