Scatter-hoarding rodents are known to play a crucial role in seed dispersal of many plant species. Numerous studies have shown significantly positive relationships between seed size and scatter-hoarding rodent preferences for seed harvest, removal, caching and dispersal distance. However, it is difficult to detect which of the two, seed size or energy content, contributes more, especially across species.

Dr. WANG Bo and his teachers of Xishuangbanna Tropical Botanical Garden (XTBG) ever used artificial seeds made from clay and peanut powder to investigate foraging preference of scatter-hoarding rodents. In another experiment, the researchers used similar artificial seeds and tried to test the interactive effects of both seed size and energy content on the rodent foraging preference. To further explore how seed size and energy content affect scatter-hoarding rodent foraging preferences, they manipulated seed size and energy content levels by using an artificial seed system as before.

In a new study, the researchers created 99 different treatments of artificial seeds with 11 seed sizes, with each seed size having 9 levels of energy content. They aimed to evaluate the effects of seed size and energy content separately, and also their interactions.

In the study, both seed size and energy content were significantly related to rodent foraging behavior, but their effects varied according to the different stages of the scatter-hoarding process. In general, rodents preferred medium-sized and high energy content seeds. High energy seeds were harvested at much more rapid rates while seed size had a limited effect on harvest rate. On the other hand, seed size was more important for the remaining scatter-hoarding stages: seed removal or consumption in situ, decision on dispersal distance, and seed caching or consumption after removal.

The study entitled “Teasing apart the effects of seed size and energy content on rodent scatter-hoarding behavior” has been published in PLoS ONE.