Influence of Age and Prior Experience on Territorial Behavior and the Costs of Defense in Male Collared Lizards

Territory defense evolves when the benefits of maintaining exclusive access to areas containing one or more resources essential for survival and reproduction exceed the costs of excluding competitors (Brown 1964; Brown & Orians 1970; Emlen & Oring 1977; Davies & Houston 1984; Stamps 1994). Defense costs may include the time and energy expended in aggressive contests and displays (Marler & Moore 1988, 1989; Vehrencamp et al. 1989; Marler et al. 1995; Hack 1997) especially when asymmetries in the physical attributes of competitors are small (Parker 1974; Leimar & Enquist 1984). Territorial defense may also increase mortality as a consequence of high energetic costs (Marler & Moore 1988; Dufty 1989) or increased predation risk (Tuttle & Ryan 1981; Ryan et al. 1982; Bradbury et al. 1989; Whitehouse 1997a; Lange & Leimar 2001). Lastly, defense of territories may interfere with opportunities to court and mate with females (Clutton-Brock et al. 1979: Baird et al. 2001). Because territorial defense is costly, it is reasonable to hypothesize that natural selection may act on the behavior of defenders in ways that reduce costs and hence increase the net benefit of spatial defense. Territory owners sometimes reduce defense costs by decreasing aggression towards familiar occupants of Correspondence Troy A. Baird, University of Central Oklahoma, 100 N. University Drive, Edmond, OK 73034, USA. E-mail: [email protected]