Apostlebirds & Cooperative breeding

PhD thesis: The Effect of Genetic Structure and Social Networking on the Acoustic Communication of Cooperative breeding Apostlebirds, Struthidea cinerea

My PhD study system, Apostlebirds (Struthidae cinerea), at UNSW Arid Zone Field Station at Fowlers Gap, was an ideal system for studying the interaction of acoustic communication with genetic and social networks. This population of 120+ birds had been monitored since 2004 and all individuals (>500) have been colour-banded and blood sampled.

A large diversity of animals engage in cooperation and cooperative behaviours. Many studies have examined the variety of factors influencing decisions to engage in cooperative behaviours as well as studying the effects of the costs and benefits of cooperation to an individual’s survival and reproduction. Examining communication of animals involves not only understanding the information content of calls, but how information is transferred between individuals. Communication influences interactions between individuals or groups of individuals and ties into animal social networks. Social network analysis examines how animals are connected and associated with other individuals and allows for study of how animal societies form and maintain their social networks.

Apostlebirds are a relatively familiar bird in the Australian bush and outback. These socially living, cooperative birds are extremely vocal (see video) and yet their acoustic communication has not yet been studied. Group composition is highly complex, with groups comprised of both close relatives and unrelated helpers. My project uses the genetic framework of the study population to shed light on acoustic communication in the context of this society. Examining the role of genetic and social structure on call repertoire, structure and complexity will provide insight into how vocalisations develop and change over time both within and between birds in different groups, as well as provide insight into how these birds mediate and maintain cooperation.

Understanding how animals communicate and share information is directly applicable to conservation of many species. Many species of both birds and mammals learn some of their skills from other members of their species. Any species with social behaviours and frequent interactions between individuals may benefit from studies focusing on social behaviours such as communication, social networks and culturally transmitted skills.

Principal Supervisor: Dr. Simon Griffith

Publications from my thesis:

Warrington, Miyako H., Rollins, Lee Ann; Russell, Andrew F.; Griffith, Simon C. 2015. Sequential polyandry through divorce and re-pairing in a cooperatively breeding bird reduces helper-offspring relatedness. Behavioral Ecology and Sociobiology, 69(8), 1311-1321. doi: 10.1007/s00265-015-1944-7.

Warrington, Miyako H.; McDonald, Paul G.; Griffith, Simon C. 2015. Within-group vocal differentiation of individuals in the cooperatively breeding apostlebird. Behavioral Ecology 26: 493-501. doi: 10.1093/beheco/aru217.

Warrington, Miyako H.; McDonald, Paul G.; Rollins, Lee Ann; Griffith, Simon C. 2014. All signals are not equal: acoustic signalling of individuality, sex and breeding status in a cooperatively breeding bird. Animal Behaviour 93, 249-260. doi: 10.1016/ j.anbehav.2014.05.007.

Warrington, Miyako H.; 2014. McDonald, Paul; Sager, Aliza K; Griffith, Simon C. The vocal repertoire of the cooperatively breeding Apostlebird, Struthidae cinerea. Emu, 114:206-221, doi: 10.1071/MU13051

Warrington, Miyako H., Rollins, Lee Ann; Raihani, Nichola J.; Russell, Andrew F.; Griffith, Simon C. 2013. Genetic monogamy despite variable ecological conditions and social environment in the cooperatively breeding apostlebird. Ecology and Evolution 3: 4669-4682.

Apostlebirds and cooperative breeding

Apostlebirds are sexually monomorphic ground foraging passerine birds that live in sedentary groups averaging 3-20 members (Woxvold 2004). They are highly social, and no group has been found to successfully fledge offspring without the aid of helpers (Woxwold & Magrath 2005). During the breeding season the birds break into sub breeding groups with multiple adults raising a single brood of chicks. This type of breeding system is referred to as cooperative breeding. During the non-breeding season social groups aggregate and individuals live together in larger groups (up to 40 members). This fission-fusion society lends to interesting questions about social networks and association.

Cooperative breeding is a reproductive system in which members of a social unit provide care to young that are not their own offspring. Care of young usually entails providing food, but may also include parental duties such as nest building, incubation, defense against predator and territorial defense. Helpers or auxiliaries may be non-breeding adults (Dickinson & Hatchwell 2004), or may be co-breeders, sharing reproduction with other group members (Dickinson & Hatchwell 2004). Helpers gain benefits through a variety of mechanisms including shared resources, predator avoidance, breeding experience and territory inheritance, and reproductive fitness through kin selection.

Kin selection is regarded as important in the evolution of helper systems. Helpers gain reproductive success through indirect fitness by providing aid to the closest genetic relatives (Dickinson & Hatchwell 2004; Stacey & Koenig 1999). Therefore, an individual’s ability to recognize and discriminate between kin and non-kin is crucial for maximizing reproductive fitness. Finer kin discrimination may be especially beneficial in societies with networks of kin of varying relatedness (ie. Noisy miner, white fronted bee-eater).

Kin discrimination may be accomplished through multiple modes including visual and acoustic means, with the underlying mechanisms being recognition alleles, phenotype matching, associative learning and spatially based recognition. However, to date, the mechanism of kin recognition underlying cooperative breeding is poorly understood (Komdeur & Hatchwell 1999). In avian recognition systems, vocalizations are the most frequently used cues (Beecher 1988; Halpin 1991). However, reliabilities of vocal cues depend in part on how they are acquired (Waldman 1987; Beecher 1988; Halpin 1991). Genetically determined cues may lead to recognition errors due to the effects of recombination, and environmentally derived cues are only reliable if acquired at a time when there is good evidence of kinship (Sharp 2005).