The behaviours of sentinels and benefits of philopatry in helpers of the cooperatively breeding chestnut-crowned babbler (Pomatostomus ruficeps)

Abstract

Numerous studies have shown that an understanding of cooperative breeding requires a thorough knowledge of the processes promoting family living and the key driving benefits behind seemingly cooperative behaviours displayed by groups. Sentinel behaviour is an important behaviour to study as it does not necessarily direct care towards kin, but to the group as a whole and so understanding the benefits attained from this behaviour are imperative to understanding social and cooperative behaviours as a whole. There is some debate as to whether sentinel behaviour is indeed cooperative or selfish and this is explored in chapter 1 by investigating the sentinel behaviour and its associated benefits in chestnut-crowned babblers (Pomatostomus ruficeps), an obligate cooperatively breeding bird of south-eastern Australia. One way in which cooperative breeders can focus their help towards kin is to remain philopatric. The benefits of philopatry hypothesis suggests that it is not ecological constraints on outside territories that promotes delayed dispersal but that some territories are worth remaining on and provide greater benefit than dispersing. To provide evidence for this, we investigate the differences between territories with differing habitat features and the effect this has on group provisioning. The territories and the habitats did not significantly affect provisioning behaviour of chestnut-crowned babblers, and did not significantly impact group sizes. Thus, we found little evidence for the benefits of philopatry as a process behind delayed dispersal in chestnut-crowned babblers and discuss this in chapter 2.