Autopreening behaviour may convey information about internal social state in Arabian babbler (Turdoides squamiceps) allopreening dyads

When individuals groom or preen one another (allopreening), vulnerability and physical access allow for information about hierarchy and bonds to be exchanged, in addition to basic health benefits. During these interactions, individuals may also self-direct grooming/preening (autopreening). We investigate autopreening in a cooperatively breeding passerine bird, the Arabian babbler (Turdoides squamiceps) in the specific context of allopreening interactions. Auto- and allogrooming (the mammalian analogue behaviours) may occur in sequence together, with some species socially facilitating allogrooming by autogrooming. We here consider the possibility of similar associations between autopreening and allopreening. Using a two-year database of 35 individuals in 8 social groups, we assessed the social factors that predict the occurrence of autopreening and its timing in the context of allopreening dyad formation. We ask if there is a social dimension to this behaviour, and specifically find evidence that it may represent displacement and/or subordinate behaviour. The relative age of individuals in preening dyads and the behaviour of recipients prior to social approach significantly predicted the behaviour of recipients as the preening dyad was formed: recipients were less likely to autopreen before approaching older actors to begin an allopreening bout. When recipients autopreened, actors were more likely to make the approach. Recipients that did not autopreen or otherwise conspicuously display were significantly more likely to approach the actor without first autopreening. We suggest that autopreening in these bouts is a socially modulated behaviour representative of uncertainty and/or subordination.