Effect of leaf moisture on wolf spider communication

Results show that environmental moisture conditions can influence efficacy of spider communication, detection of predators, and ultimately mating success. Data include: • Laser vibrometry recordings showing that both stridulation and percussive signals maintain significantly higher amplitude over distance on dry leaves than wet leaves. • Male responses to chemical cues (courtship latency and display rate) declined after leaves with female silk became wet. • In response to predatory bird calls (Blue Jays) transmitted through leaf surfaces, courting male spiders on dry leaves responded with anti-predator “freeze” behaviors more often and for longer duration than those on wet leaves, and took longer to resume courtship than on wet leaves. • Males courted females on wet and dry leaves with equal frequency, but mating success was significantly greater on dry leaf litter.

Interestingly, visual signals increased on wet leaves, suggesting compensatory behavior in response to moisture. These findings are important because the mating season of many wolf spider species occurs in spring, when there are frequent rains, and when insectivorous birds are selectively provisioning nestlings with spiders. Consequently, increased seasonal rainfall owing to climate change may disproportionately impact the leaf litter microhabitat and change the transmission properties of leaf substrates used for communication by spiders and other invertebrates.