Dominance-specific vigilance in the tufted titmouse: effects of social context

摘要: The hypothetical benefits accruing to animals participating in foraging groups are of two classes, improved predator avoidance and enhanced efficiency (reviewed by Krebs Davies 1987). These classes often not independent; for example, there is a growing literature demonstrating that the size group influences how individuals' time budgets apportioned among such antagonistic activities as vigilance predators (e.g., Pulliam 1973, Powell 1974, Caraco 1979, Barnard 1980, Bertram et al. 1980a, Elgar Catterall 1981, Lendrem 1983, Studd 1984). Several studies on birds make this tradeoff between efficiently avoiding have demonstrated flock increases proportion allocated individuals increased, while flock's aggregate level maintained or even increased Siegfried Underhill 1975, Jennings Evans Sullivan 1984a). Most previous failed consider differing dominance status probably experience different costs associated with membership (but see Moore 1972, cited 1979; Ekman Askenmo 1984; In particular, available should be more constrained subordinates if higher-ranking conspecifics interfere their foraging. present study addresses experimentally possibility vigilant than dominants because they must keep under surveillance avoid aggressive interactions also remaining (cf. Robinson Waite 1986). Using captive Tufted Titmice (Parus bicolor), I examined nonexclusive hypotheses socially (1) (2) other members and, thus, subject control at least proximate factors, status, respectively. One prediction can generated from each these hypotheses, respectively: dominant titmouse when solitarily member dyad, subordinate forage together. METHODS