Scatter-hoarding rodents often play an important role in the reproductive ecology of many plant species. Tannins, a diverse group of water-soluble phenolic compounds with high affinity for proteins, in seeds are believed to influence rodent foraging preference. Many studies have discussed the effects of tannin on rodent foraging behavior and, in turn, seed fate. However, the results of these studies are inconsistent.

　 Dr. WANG Bo and his supervisor Prof. CHEN Jin of Xishuangbanna Tropical Botanical Garden (XTBG) have concentrated studies on the relationships between seeds and scatter-hoarding rodents for many years. To further explore how seed fat and protein concentrations influence scatter-hoarding rodent preferences on seed tannin concentrations during their whole foraging process, they manipulated seed fat, protein, and tannin content levels by using an artificial seed system.

They performed the study during the summer (July and August) and autumn (October and November) of 2009 in a pine forest in the Shangri-La Alpine Botanical Garden, Hengduan Mountains, Yunnan Province, Southwestern China (27° 54′ N, 99° 38′ E, alt. 3456 m).

In the study, they manipulated seed tannin and fat/protein levels to examine directly the univariate effects of each component on the seed preferences of free-ranging forest rats (Apodemus latronum and Apodemus chevrieri) during the behavioral process of scatter hoarding.

In addition, they recorded the time (days) to seed harvest, seeds removal vs. being eaten in situ, and distance of seeds carried by rodents.

They tested the following hypotheses: (1) seeds with low tannin and/or high fat/protein content are more likely to be harvested by rodents than seeds with high tannin and low fat/protein content; (2) seeds with low tannin and/or high fat/protein content are harvested more quickly by rodents; (3) seeds with low tannin and/or high fat/protein content are carried to further distances by rodents; (4) both fat and protein might attenuate the exclusion of seeds with higher tannin concentrations by rodents, thus influencing seed fate.

In their study, tannin, fat, and protein all showed significant effects on rodent foraging behavioral processes. However, additional seed traits, other than those evaluated in their study, may also influence rodent foraging behavior.

The study entitled “Effects of Fat and Protein Levels on Foraging Preferences of Tannin in Scatter-Hoarding Rodents” has been published in PLoS ONE 7(7): e40640. doi:10.1371/journal.pone.0040640