title: Warning signals confer advantage to prey in competition with predators: bumblebees steal nests from insectivorous birds.
abstract: Aposematic (warning) signals of prey help predators to recognize the defended distasteful or poisonous prey that should be avoided. The evolution of aposematism in the context of predation has been in the center of modern ecology for a long time. But, the possible roles of aposematic signals in other ecological contexts have been largely ignored. Here we address the role of aposematic signals in competition between prey and predators. Bumblebees use visual and auditory aposematic signals to warn predators about their defenses. For 2 years, we observed competition for nestboxes between chemically defended insects,Bombus ardens(and possibly alsoBombus ignitus), and cavity nesting birds (Parus minorandPoecile varius). Bumblebees settled in 16 and 9 % of nestboxes (in 2010 and 2011 breeding seasons, respectively) that contained bird nests at the advanced stage of nest building or at the stage of egg laying. Presence of bumblebees prevented the birds from continuing the breeding activities in the nestboxes, while insects took over the birds' nests (a form of kleptoparasitism). Playback experiments showed that the warning buzz by bumblebees contributed to the success in ousting the birds from their nests. This demonstrates that aposematic signals may be beneficial also in the context of resource competition.
authors.affiliation: Laboratory of Behavioral Ecology and Evolution, School of Biological Sciences, College of Natural Sciences, Seoul National University, Seoul, 151-742 South Korea ; Centre for Ecological Research [formerly Institute of Ecology], Polish Academy of Sciences, Dziekanow Lesny, Poland.
authors.forename: Piotr G
authors.initials: PG
authors.lastname: Jablonski
authors.forename: Hyun Jun
authors.initials: HJ
authors.lastname: Cho
authors.forename: Soo Rim
authors.initials: SR
authors.lastname: Song
authors.forename: Chang Ku
authors.initials: CK
authors.lastname: Kang
authors.forename: Sang-Im
authors.initials: SI
authors.lastname: Lee
keywords: Auditory warning signals; Bombus; Distant taxa; Kleptoparasitism; Nestbox; Paridae; Parus minor; Poecile varius; Resource competition