干旱区生态环境知识资源中心

More often than not, animals forage with other foragers present. A foraging game may take place when the outcome of a forager’s actions depends on both its own and other foragers’ strategies. Previous studies on predator-prey systems have verified that complex state-dependent foraging games exist between predators and prey. In this study, we looked for evidence of such a state-dependent foraging game between intra-guild competitors. We studied a desert rodent system featuring 2 coexisting species known to compete with each other: midday gerbils (Meriones meridianus, the dominant competitor) and 3-toed jerboas (Dipus sagitta, the subordinate competitor). We simultaneously manipulated the energetic states of both species and allowed them to forage and interact in arenas with artificial food patches. We found that both species responded to their own energetic states, whereas hungry jerboas also significantly responded to gerbils’ energetic state in terms of food harvest. Gerbils preferred to carry food items away when foraging alone but switched to on-tray consumption when jerboas were present. Jerboas harvested more food when gerbils were hungry and the most intensive interference occurred when hungry jerboas encountered well-fed gerbils. A plausible explanation for these results is that the future rather than current value of cacheable food is more important to well-fed gerbils. In contrast, hungry gerbils prefer immediate consumption to completely excluding jerboas from resource patches.