Presampling sensory information and prey density assessment by wolf spiders (Araneae, lycosidae)

Abstract

Decisions regarding foraging patch residence time and the assessment of patch quality may be mediated by various sources of information. This study examined the use of sensory cues by hunting spiders to assess prey density in the absence of prey capture. Adult female wolf spiders [Schizocosa ocreata (Hentz); Lycosidae] had food withheld for 4 days and then were exposed to artificial foraging patches containing four densities of crickets (0, 3, 10, 20) with different sensory stimuli (visual and vibratory information, visual only, and vibratory only). The spiders were not allowed to feed during trials, and patch residence time was recorded. The spiders varied patch residence time based on sensory cues alone and spent more time in patches with higher prey density. With visual information only, spiders could apparently distinguish among prey densities almost as well as with visual and vibratory cues combined, but residence time did not differ among prey densities when only vibratory information was presented. Measurements of vibration levels produced by cricket activity under experimental sensory treatments conform to test results, suggesting that visual detection of crickets is important in patch assessment used in determining patch residence time.