Foraging behaviour and the risk of predation in the black house spider, Badumna insignis (Desidae)

Many animals adjust their behaviour according to the presence or threat of predators. However, the Foraging behaviour of sit-and-wait predators is typ ically thought to be inflexible to short-term changes in the environment. H ere we investigate the foraging behaviour of the nocturnally active black h ouse spider, Badumna insignis. Experiments in which different kinds of prey were introduced into the web during either the day or night indicated that the foraging success of Badumna is compromised by behaviours that reduce t he risk of predation. During the day, spiders generally remain within the r etreat and take longer to reach the prey, which may reduce their foraging s uccess. In contrast, spiders sat exposed at the edge of the retreat at nigh t, and from here could usually reach the prey before it escaped. The spider s were able to escape from a model predator more rapidly if they were at th e edge of the retreat than if they were out on the web. These data suggest that the costs to Badumna of reduced fecundity through poor foraging effici ency may be outweighed by the benefits of reducing the risk of predation.