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In carrion crows ( ), patterns of NF (~7% of nest visits) and FF (~9% of nest visits) were unaffected by an apparent audience and seldom resulted in aggression (~3% of false-feeds) ( Canestrari 2004 ).
In white-winged chough ( ), for example, helpers have been observed to visit the nest with food, invariably wait until the current nest attendant departs, and then consume the prey item themselves (11% of nest visits; Boland et al. Such behavior, when detected by other group members ( = 3 occasions), led to apparent retribution.For example, if FF occurs for the latter reasons suggested, it is not deceptive; hence would not be expected to lead to retribution ( Semple and Mc Comb 1996 ).In addition, low levels of aggression need not be at odds with signaling-based hypotheses, if threats are sufficient to police potential defectors ( Cant 2011 ).Cooperative breeding systems, wherein individuals provide care to the offspring of others (hereafter referred to as helpers), represent a challenging case study.Broadly, five adaptive hypotheses are commonly invoked to account for the apparent altruistic behavior of nonbreeding helpers ( Emlen 1991 ; Cockburn 1998 ; Bergmüller et al. Kin selection proposes that helpers suffer personal fitness costs, which are offset by the fitness benefits helpers confer on relatives that share genes by descent ( Hamilton 1964 ).