Data from: Producers and scroungers: feeding type composition changes with group size in a socially foraging spider

In groups of socially foraging animals, feeding behaviour may change with group size in response to varying cost-benefit trade-offs. Numerous studies have described group size effects on group-average feeding behaviour, particularly emphasizing an increase in scrounging incidence for larger groups, where individuals (scroungers) feed from the food sources others (producers) discovered. However, individual variation in feeding behaviour remains unconsidered in the vast majority of these studies even though theoretical models presume individuals to specialize in feeding tactic and anticipate higher scrounger-type frequencies in larger groups. We combined group-level and individual-level analyses of group size effects on social foraging in the subsocial spider Australomisidia ergandros. Lending novel experimental support to model predictions, we found that individuals specialize in feeding tactic and that higher scrounging and lower producing incidence in larger groups were mediated through shifts in the ratio of feeding types. Further, feeding type specialization was not explained by innate individual differences in hunting ability as all feeding types were equally efficient in prey capture when foraging alone. Context adaptivity of feeding behaviour might allow this subsocial species to succeed under varying socioecological conditions.

Usage Notes
DATA from communal and single feeding experimentsThis excel file contains the individual feeding parameters obtained from communal feeding trials (sheet 1) and single feeding trials (sheet 2). It further contains individual descriptive parameters such as group size, group ID, weight and weight rank measures that were used as predictors in the statistical analyses. The individual feeding parameters are explained in Table 1 as well as in the descriptions of the communal and single feeding experiment in the "Methods"-section of the manuscript.DATA for MS - Feeding type composition changes with group size.xlsx

在社会性觅食动物群体中，觅食行为可能随着群体规模的改变而变化，这是对成本效益权衡的响应。众多研究描述了群体规模对群体平均觅食行为的影响，尤其是强调在大群体中觅食行为的发生率增加，其中个体（寻食者）从其他个体（生产者）发现的食源中觅食。然而，在绝大多数这些研究中，觅食行为的个体差异尚未被考虑，尽管理论模型假定个体在觅食策略上具有专业性，并预测在大群体中寻食者类型的频率会更高。我们结合了群体水平和个体水平分析，探讨了群体规模对亚社会性蜘蛛Australomisidia ergandros社会性觅食的影响。为模型预测提供新颖的实验支持，我们发现个体在觅食策略上具有专业性，且在大群体中寻食频率较高、生产频率较低的现象是通过觅食类型比率的转变来介导的。此外，觅食类型的专业性并非由狩猎能力的先天个体差异所解释，因为在单独觅食时，所有觅食类型在猎物捕获方面均具有相同的效率。觅食行为的情境适应性可能使这种亚社会性物种能够在不同的社会生态条件下取得成功。