title: Host response to cuckoo song is predicted by the future risk of brood parasitism.
abstract: BACKGROUND
  Risk assessment occurs over different temporal and spatial scales and is selected for when individuals show an adaptive response to a threat. Here, we test if birds respond to the threat of brood parasitism using the acoustical cues of brood parasites in the absence of visual stimuli. We broadcast the playback of song of three brood parasites (Chalcites cuckoo species) and a sympatric non-parasite (striated thornbill, Acanthiza lineata) in the territories of superb fairy-wrens (Malurus cyaneus) during the peak breeding period and opportunistic breeding period. The three cuckoo species differ in brood parasite prevalence and the probability of detection by the host, which we used to rank the risk of parasitism (high risk, moderate risk, low risk).
  
  
  RESULTS
  Host birds showed the strongest response to the threat of cuckoo parasitism in accordance with the risk of parasitism. Resident wrens had many alarm calls and close and rapid approach to the playback speaker that was broadcasting song of the high risk brood parasite (Horsfield's bronze-cuckoo, C. basalis) across the year (peak and opportunistic breeding period), some response to the moderate risk brood parasite (shining bronze-cuckoo, C. lucidus) during the peak breeding period, and the weakest response to the low risk brood parasite (little bronze-cuckoo, C. minutillus). Playback of the familiar control stimulus in wren territories evoked the least response.
  
  
  CONCLUSIONS
  Host response to the threat of cuckoo parasitism was assessed using vocal cues of the cuckoo and was predicted by the risk of future parasitism.
authors.affiliation: School of Biological Sciences, Flinders University, Adelaide, 5042, South Australia. diane.colombelli-negrel@flinders.edu.au.
authors.forename: Sonia
authors.initials: S
authors.lastname: Kleindorfer
authors.forename: Christine
authors.initials: C
authors.lastname: Evans
authors.forename: Diane
authors.initials: D
authors.lastname: Colombelli-Négrel
authors.forename: Jeremy
authors.initials: J
authors.lastname: Robertson
authors.forename: Matteo
authors.initials: M
authors.lastname: Griggio
authors.forename: Herbert
authors.initials: H
authors.lastname: Hoi