The Effects Of Seed Size On Foraging Decisions By Pére David’s Rock Squirre

Animal foraging decisions not only affect their own survival and reproduction, but also affects the fate of food(seed), in the long-term evolution proves, between animals and plants have been widely formed reciprocal or cooperative coevolution relationship. The behavioral decision of what to eat or hoard is extremely important for the survival and reproductive success of hoarding animals. The characteristics of food items(e.g. seed size, tannin content, and germination schedules) are thought to be key factor that influences such behavioral decisions of food hoarding animals. The acorn relies mostly on animals such as squirrels to spread their seeds by means of distributed storage. Produced by oak species(Quercus sensu lato, Fagaceae) across the North Hemisphere, Acorns exhibit two relatively distinct germination strategies among the three well-studied oak groups: most white oaks( Section Quercus) in both Eurasia and North America produce nondormant acorns(germination shortly after maturity), while red oaks(Section Labatae) in North America and Qinggang oaks(Section Cylobalanopsis) in Asia often produce dormant acorns(germinate the following spring or even much later). For hoarding animals, as both seed predators and dispersers, rapid germination(i.e. nondormancy) of seeds is one major cause of food perishability owning to energy and nutrients being lost during storage. The trait renders WO acorns a highly perishable food source, in appropriate for long-term storage. Some rodent species have evolved species behavioral strategies(e.g. embryo removal) to prevent or delay seed germination during the hoarding process. Due to the embryos removal acorn germination rate is extremely low, so the behavioral obviously unfavorable to the spread of the nondormant white oak acorns and natural regeneration. The oaks produce acorns with different quantity and size in the intraspecific level, and other animals foraging decisions are affected by the seed size, may be white oak plant to realize the important mechanism of the seed dispersal. In this study, we investigated how free-ranging Pére David’s rock squirrel Sciurotamias davidianus manipulated acorns contrasting seed size from two common white oaks(Quercus variabilis and Quercus aliena var. acutesevata) in a deciduous broadleaf in Central China. The main results and conclusions of this research are as follows:1) The David’s rock squirrel handles food items using four overt behavioral categories- Sniffing, Eating, embryo removal and hoarding. Four main behaviors can be summarized as three main patterns of behavior. The take more time to eat an acorn than to store it, ant that squirrels were more likely to scatter hoard acorns.2)For both white acorns, Seed size had significant effect on selected order, The seed weight, the greater the probality of seeds are rock squirrels preference is higher. Give priority to the selected seed, has higher storage an embryo. In addition, the diffusion distance of seed and seed selection was significantly positively related to order.3)Seed seize had significantly affect rock squirrels handle different size of the weight of QV or QAA adopt patterns of behavior, seed weight, the greater the rock squirrels cut to the higher the probability of the embryo storage mode, the smaller seed weight, rock squirrels main tendency feeding patterns. David’s rock squirrel processing seed embryo and storage time were along with the increase of seed weight increased significantly, the results support the seed size hypothesis. Cut embryo seed weight, the greater the probability is higher, that kind of seed size variation within the significant impact on rock squirrels cut into the embryo.4)Squirrels preference to hoarding larger seed with embryo removal,and eat small seed,may help some weight in a medium size seeds escape rock squirrels removal embryos behavior, realize the spread of the seeds and updated. White oak seed size variation effect on rock squirrels foraging decision, implementation is likely to be white oak seed diffusion and plants is an important mechanism of updates.