Song Post Height in Relation to Predator Diversity and Urbanization (pages 529–538).pdf

Song Post Height in Relation to Predator Diversity and Urbanization Anders P. M?ller Laboratoire d’Ecologie, Syste?matique et Evolution, CNRS UMR 8079, Universite? Paris-Sud, Orsay Cedex, France Introduction Song posts (microsites used by animals when sing- ing) are chosen to maximize transmission or mini- mize attenuation, while simultaneously avoiding predation (M?ller et al. 2008). Exposed song posts may enhance sound perception, but also provide better vision of potential approaching potential pre- dators and potential rivals and mates (e.g. M?ller et al. 2008; Lima 2009). Choice of signaling environ- ment may increase the risk of predation causing feedback on habitat selection (Andersson 1994). Fur- thermore, different habitats have different transmis- sion properties, and vocal signals show design features that suggest that they have been modified to facilitate efficient transmission in particular habi- tats (e.g. Wiley Richards 1982; Slabbekoorn Smith 2002). Previous studies of habitat choice for singing suggest that higher positions in the vegeta- tion do not necessarily benefit transmission of sound, but may facilitate perception (e.g. Dabelsteen et al. 1993; Holland et al. 1998). Song posts may be expected to be sensitive to selection, as the com- bined cost of production and thermoregulation at exposed song posts can represent a significant ener- getic cost (Ward Slater 2004). M?ller et al. (2008) estimated exposure of song posts used by passerine birds in relation to prey susceptibility to the sparrow- hawk Accipiter nisus with susceptibility increasing with increasing song post exposure. Comparative models controlling for the potentially confounding effects of habitat, sexual dichromatism, hole nesting, coloniality, body mass, cognitive capacities, and fly- ing abilities indicated that the relationship between prey susceptibility and song post exposure is strong. Path analyses of the relationship between song post Correspondence Anders P. M?ller, Lab