In a hole in the ground there lived a spider: Microhabitat preference and burrow architecture in natural populations of Sydney funnel-web spiders (Atrax robustus)

Abstract: The microhabitat an animal occupies is expected to be selected for and optimal for that animal. However, little is known about the microhabitat features selected by small sedentary animals such as ground dwelling spiders. In this study we investigate the microhabitat preferences of the Sydney funnel web spider, Atrax robustus, in the wild. We show that the spiders select microhabitats characterised by certain substrates and structural features for their burrows. In particular, A. robustus individuals strongly prefer to burrow against solid structures such as rocks or trees. Above ground, all burrows had silk triplines radiating from the burrow entrance with variable amounts of silk ‘funnelling’ present, ranging from triplines alone to extensive silk tubing (funnel). Below ground, the burrows were always associated with a tree root or a rock and typically had a single tunnel ending in a widened chamber. However, burrows varied considerably in size, direction and shape, usually twisting to follow the contour of the root or rock underground. The insights gained from this study can inform future conservation efforts of small, sedentary terrestrial animals, as well as increasing our understanding of Sydney funnel-web spider ecology.摘要： 动物所占据的微生境通常被认为是经过自然选择且适配其生存的最优生境。然而，学界对小型定居地栖动物（如地栖蜘蛛）所偏好的微生境特征仍了解有限。本研究针对野生环境下的悉尼漏斗网蜘蛛（Atrax robustus）的微生境偏好展开调查。研究结果表明，该蜘蛛会选择具备特定基质与结构特征的位点挖掘洞穴。具体而言，悉尼漏斗网蜘蛛个体强烈倾向于在岩石、树木等硬质结构旁构筑洞穴。 在地面以上区域，所有洞穴的入口处均布有呈放射状延伸的蛛丝牵引线（triplines），且伴随数量不等的蛛丝“漏斗状结构”，覆盖范围从仅存在牵引线到形成大面积的蛛丝管状结构（funnel，即漏斗）不等。 地下层面，所有洞穴均与树根或岩石相关联，通常以单条隧道末端连接一处加宽的巢室为典型结构。不过，不同洞穴的尺寸、走向与形态差异显著，通常会蜿蜒以贴合地下树根或岩石的轮廓。 本研究获得的研究成果，可为未来小型定居陆生动物的保护工作提供科学参考，同时也有助于深化学界对悉尼漏斗网蜘蛛生态学的认知。