title: Plant structural complexity and mechanical defenses mediate predator-prey interactions in an odonate-bird system.
abstract: Habitat-forming species provide refuges for a variety of associating species; these refuges may mediate interactions between species differently depending on the functional traits of the habitat-forming species. We investigated refuge provisioning by plants with different functional traits for dragonfly and damselfly (Odonata: Anisoptera and Zygoptera) nymphs emerging from water bodies to molt into their adult stage. During this period, nymphs experience high levels of predation by birds. On the shores of a small pond, plants with mechanical defenses (e.g., thorns and prickles) and high structural complexity had higher abundances of odonate exuviae than nearby plants which lacked mechanical defenses and exhibited low structural complexity. To disentangle the relative effects of these two potentially important functional traits on nymph emergence-site preference and survival, we conducted two fully crossed factorial field experiments using artificial plants. Nymphs showed a strong preference for artificial plants with high structural complexity and to a lesser extent, mechanical defenses. Both functional traits increased nymph survival but through different mechanisms. We suggest that future investigations attempt to experimentally separate the elements contributing to structural complexity to elucidate the mechanistic underpinnings of refuge provisioning.
authors.affiliation: Department of Entomology and Nematology University of California Davis CA USA.
authors.forename: Patrick
authors.initials: P
authors.lastname: Grof-Tisza
authors.affiliation: Department of Entomology and Nematology University of California Davis CA USA; Ecology Graduate Group University of California Davis CA USA.
authors.forename: Eric
authors.initials: E
authors.lastname: LoPresti
authors.affiliation: Ecology Graduate Group University of California Davis CA USA; Department of Environmental Science and Policy University of California Davis CA USA.
authors.forename: Sacha K
authors.initials: SK
authors.lastname: Heath
authors.affiliation: Department of Entomology and Nematology University of California Davis CA USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Karban
keywords: Red‐winged Blackbirds; associational refuge; indirect effects of species interactions; positive facilitation; predation refuge