Cooperative Breeding & Sociality in Birds

Coordinators

Dr Mandy Ridley (UCT Honorary Research Associate and Macquarie University)
Prof. Phil Hockey (PFIAO)

Research Team

Mr Mark Anderson (BirdLife South Africa)
Ms Anne Braae
Dr Rita Covas (CIBIO, University of Porto and PFIAO, University of Cape Town)
Dr Claire Doutrelant (CEFE-CNRS)
Prof.  Ben Hatchwell (‘Nest building’ project; Sheffield University)
Mr Eric Herrmann (PFIAO)
Prof. Gerard Malan (Tshwane Univ. of Technology, SA)
Ms Kate Meares (PFIAO)
Dr Martha Nelson-Flower (PFIAO)
Dr Andrew Radford (Univ. Bristol, UK)
Dr Mandy Ridley (UCT)
Ms Sieglinde Rode (PFIAO & Tshwane Univ. Technology)
Mr Adin Ross-Gillespie (PFIAO)
Dr Lizanne Roxburgh (PFIAO)
Dr Doug Schaeffer (PFIAO & Univ California Berkeley)
Dr Robert Simmons (PFIAO)
Dr Andrew Taylor
Mr Alex Thompson (PFIAO)
Dr René van Dijk (‘Nest building’ project; Sheffield University)
Prof. Joseph B. Williams (Ohio State Univ., USA)

Overview

Cooperative breeding describes a social system in which animals live in groups, most often of closely related individuals. Within a group, usually only the dominant pair breed, but the other group members (subordinates/helpers) assist in rearing the offspring, despite not being the parents. This creates an apparent conundrum in terms of Darwinian precepts and the search for a unifying theory that explains the evolution of cooperative breeding remains one of the most tantalising holy grails of behavioural ecology. Globally, it is a rare social system – only about 3% of the world’s birds are thought to breed cooperatively (although most of these species are capable, at least under some conditions, of breeding successfully without helpers). Some of these cooperative breeders have been the focus of intense study, often concentrating on the extent to which helpers contribute to group reproductive success. Results of these studies have proved inconclusive in terms of developing a unifying theory to explain the behaviour. In some species, helpers are beneficial to group reproductive performance, yet in others they seemingly confer no benefit or may even be detrimental. The Fitztitute has embarked on four major studies of cooperative breeding – in Green Wood-Hoopoes Phoeniculus purpureus and Karoo Scrub-Robins Cercotrichas coryphoeus (both recently concluded), and Sociable Weavers Philetairus socius and Southern Pied Babblers Turdoides bicolor (both ongoing). The two ongoing projects have, in the last few years, highlighted a key issue about studies of cooperative breeding and its origins – have we been asking the right questions in the right way? As the scientific tool kit grows ever larger and more sophisticated, the answer to that question increasingly seems to be ‘perhaps not’. If the unifying theory is within grasp, history tells us that it might be uncovered only by modifying the search pattern. This is something that recent research at the Fitztitute has attempted to do by using a diversity of research approaches.

Southern Ground Hornbill Research and Conservation Programme

Research Team: Phil Hockey & Kate Meares

The Southern Ground-Hornbill Bucorvus leadbeateri is a conservation icon of South African savannas. During the 20th Century its range and population size in South Africa decreased by some two thirds, with the birds disappearing from much of their historical range. Such a rapid decrease in the population of a long-lived, slow-reproducing animal is of great conservation concern and, based on IUCN criteria, the official conservation status of Southern Ground-Hornbills in South Africa has been elevated from Vulnerable to Critically Endangered. In many cases, however, the drivers of local extinctions are known, and in some instances these are no longer operative. Because of the ground-hornbills’ complex social structure, self-reintroduction would, at best, be very slow. This means that reintroduction programmes are probably imperative to improve the species’ precarious conservation status.

Given this set of circumstances, the Fitztitute’s Southern Ground-Hornbill Research Programme aims to gain a scientific understanding of the environmental conditions which promote the survival and successful reproduction of these birds. We will use this knowledge to identify areas previously occupied by ground-hornbills that are now suitable for their reintroduction. We will then provide scientific information to guide reintroduction programmes such that their efficiency and efficacy are optimized. The ultimate aim of these studies of habitat use patterns by ground-hornbills with different lifetime reproductive outputs is therefore to optimise sites and protocols for reintroduction programmes.

In 2000, the Institute started monitoring groups of ground-hornbills in the Associated Private Nature Reserves (APNR), a 180 000 ha conservancy adjacent to Kruger National Park. The original rationale for this study was an exploration of social behaviour in the world’s largest cooperatively breeding bird. However, on the basis of this 8-year data set (from 23 groups) we were able to identify environmental and social correlates of breeding performance. This analysis allowed the project to enter a strongly conservation-orientated phase. An interesting finding was that habitat configuration strongly influenced breeding success, demanding that we investigate how the groups use their very large (up to 100 km2) home ranges. To do this we are using solar-powered satellite transmitters on groups in the APNR. We have also teamed up with the Ground-Hornbill Reintroduction Programme based to the west of the APNR at Mabula Game Reserve to study a habituated, but wild-living group of ground-hornbills with the aim of determining how much information is lost by having satellite fixes from the APNR at hourly, rather than shorter intervals.

Pied Babbler Research Project

Research Team: Amanda Ridley (Team Leader), Nichola Raihani, Martha Nelson-Flower, Krystyna Golabek, Alex Thompson, Dave Humphries, Fiona Finch

Pied Babblers (Turdoides bicolor) are obligate cooperative breeders that live in groups of 3-14 adults which occupy and defend territories year-round. The Pied Babbler Research Project in the Kalahari focuses on the behavioural ecology of habituated groups and on the causes and consequences of helping behaviour, parent-offspring conflict, kin recognition, sexual selection and vocal communication in particular. See Pied Babbler Research Project for more details.

Sociable Weaver Research Project

Research team: Rita Covas (Team Leader), Claire Doutrelant, René van Dijk & Ben Hatchwell

Sociable weavers Philetairus socius are highly social passerines of the semi-arid savannas of the Kalahari region in southern Africa. They cooperate to build large thatched colonies which they occupy throughout the year. They also cooperate to raise their young, with 30-80% of nests being attended by a group consisting of the breeding pair and 1-5 helpers. We have a long-term study on the sociable weavers at Benfontein Game Farm, near Kimberley, where we investigate fascinating aspects of the species’ cooperative behaviour, life-history and population dynamics. Of particular interest are the benefits and consequences of sociality and cooperation in this species, understanding dispersal patterns and population dynamics, and how cooperation is achieved in colony building. More specific projects currently ongoing are investigating maternal investment in relation to helping and dispersal patterns, the role of dominance and signalling in cooperative behaviour and how the ‘tragedy of the commons’ is avoided in nest building and maintenance. See Sociable Weaver Research Project for more details.