Balancing predator avoidance with hunting opportunities: substrate choice by Misumena vatia spiderlings

Abstract

When crab spiderlings Misumena vatia (Clerck 1757) emerge from their natal nests their small resource reserve makes them vulnerable to starvation, while their small size makes them vulnerable to many predators. Choosing substrates that allow hunting opportunities as well as protection from predators may thus be life or death decisions. Here we investigate the substrate choice of crab spiderlings on goldenrod Solidago canadensis and Solidago juncea inflorescences in relation to a frequently encountered predator, the jumping spider Pelegrina insignis (Banks 1892). Flower heads of 5. canadensis are smaller and more densely packed on branches of the inflorescences than the heads of S. juncea , but the two species attract similar numbers of small flies, the major prey of the spiderlings and jumping spiders. Crab spiderlings significantly preferred S', canadensis , both in initial choice and length of time occupied, as did their jumping spider predator. However, capture times of spiderlings by small jumping spiders (< 5 mg) did not significantly differ on the two goldenrods, although the preferred goldenrod, S. canadensis, provided superior protection from larger jumping spiders (>5 mg). Thus, although occupancy on the preferred goldenrod does not make spiderlings safer from all jumping spiders, it provides superior protection from large ones and may be the basis for the substrate preference of the spiderlings.