Colour use by tiny predators: jumping spiders exhibit colour biases during foraging

The evolution of many animal colours is thought to be driven by selection from visually guided predators. Yet research has largely focused on large vertebrate predators such as birds while ignoring smaller, terrestrial invertebrate predators. This is despite clear evidence that small invertebrate predators are important regulators of prey densities in a variety of ecosystems. Jumping spiders are small voracious predators that feed on a wide variety of prey in the field. They are capable of colour discrimination, but little is known about whether they attend to the colour of their prey during foraging. We examined colour biases by offering Habronattus pyrrithrix jumping spiders arrays of artificially coloured juvenile crickets. We found that field-collected H. pyrrithrix showed populationwide colour biases; across age and sex categories, attack rates were lowest on red and yellow prey (colours commonly used as warning colours) and highest on blue prey. We retested the same individuals af...