No evidence for deception over allocation to brood care in a cooperative bird

Abstract

The evolutionary route(s) to cooperative breeding, wherein individuals provide care to the offspring of others, remains contentious. Two hypotheses propose that such helping behavior constitutes a signal, either to remain on the current territory (pay-to-stay) or to advertise quality to potential partners (social prestige). As such, both hypotheses predict that helpers gain from perceived, rather than actual, levels of care provided. Using the chestnut-crowned babbler (Pomatostomus ruficeps), we test whether individuals attempt to increase their perceived level of care by visiting the nest without food (nonfeeding [NF]) or with food but fail to deliver it (false-feeding [FF]). We found no evidence that either NF or FF was used as a deceptive tactic, with both being more parsimoniously explained by current levels of brood demand. Most notably, categories of helpers (males, adults, immigrants) expected to be "charged" more for staying or to benefit more from advertising quality, neither nonfed nor false-fed more than other categories (females, yearlings, natals). In addition, there was no evidence that the presence of an audience (the breeding females in their domed nests) influenced the probability of NF or FF in a manner consistent with either hypothesis. Finally, the incidences of both NF and FF were low and insufficient to have significant effects on the perceived levels of care provided, even if they were used in an attempt to deceive other group members over their contributions to rearing young. We conclude that signaling-based hypotheses have, at best, a weak role in selecting for helping behavior in chestnut-crowned babblers. © 2012 The Author.