Physical and social cues shape nest-site preference and prey capture behavior in social spiders

Spatial proximity and prey vibratory cues influence collective hunting in social spiders

Social spiders are thought to predominantly receive information about their environment through vibrational cues. Thus, group living introduces the challenge of distinguishing useful vibrational information from the background noise of nestmates. Here we investigate whether spatial proximity between colony-mates may allow social spiders (Stegodyphus dumicola) to reduce background noise that might obstruct vibrational information from prey. To do so, we constructed experimental colonies and measured whether the number of spiders in proximity to one another whilst resting could predict the number of spiders that participated in prey capture. Additionally, we exposed spider colonies to five different simulated vibrational cues mimicking prey to determine which cue types spiders were most responsive to. We found that the number of spiders huddled together prior to foraging trials was positively correlated with the number of spiders participating in collective foraging. Furthermore, colonies responded more quickly to pulsed vibrational cues over other types of vibrational patterns. Together these data reveal that both social interactions and prey cues shape how social sit-and-wait predators experience and respond to their environment.

Physical and social cues shape nest-site preference and prey capture behavior in social spiders

Animals often face conflicting demands when making movement decisions. To examine the decision process of social animals, we evaluated nest-site preferences of the social spider Stegodyphus dumicola. Colonies engage in collective web building, constructing 3D nests and 2D capture webs on trees and fences. We examined how individuals and groups decide where to construct a nest based on habitat structure and conspecific presence. Individuals had a strong preference for 3D substrates and conspecific presence. Groups were then provided with conflicting options of 3D substrates versus 2D substrates with a conspecific. Groups preferred the 3D structures without presettled conspecifics over a 2D substrate with conspecifics. When a group fragmented and individuals settled on both substrates, the minority group eventually joined the majority. Before rejoining, the collective prey capture behavior of divided groups improved with the size of the majority fragment. The costs of slow responses to prey for split groups and weak conspecific attraction may explain why dispersal is rare in these spiders.