Pied Babblers and Fork-tailed Drongos
Tim Clutton-Brock established the Kuruman River Reserve to study group living in meerkats, but it has become the focus of several other long-running animal studies. Amanda Ridley’s Pied Babbler Research Project was initiated in 2003 and uses habituated, free-living groups of Southern Pied Babblers Turdoides bicolor to understand the causes and consequences of cooperative breeding behaviour. In 2006 Amanda expanded the study to include the local Fork-tailed Drongo Dicrurus adsimilis population, investigating interactions between drongos, babblers and other species. Tom Flower joined the drongo project in 2008 to continue research on species interactions, with a focus on the drongos’ use of false alarm calls to steal food from other animals.
The causes of conflict and cooperation in group-living societies
The Pied Babbler Research Project investigates the benefits of cooperation and the causes of conflict in this highly cooperative, group-living species. The population of 12-19 groups has been monitored continuously for 14 years. Group size and number varies considerably according to weather conditions in the Kalahari, with the population suffering a considerable decline following breeding seasons with poor rainfall and high temperatures. The population also declines during very cold winters, with juveniles experiencing high mortality. Long-term life history data, along with short-term observations and experimentation, have helped the team understand the causes and consequences of cooperative breeding behaviour. These findings help to reveal the benefits of cooperation not just in babblers, but from a broader evolutionary perspective.
How interactions between species shape animal behaviour
The Fork-tailed Drongo project initiated in 2006 explores how interactions with other species in an animal’s environment can shape the evolution of behaviour. The project focuses on a population of over 40 pairs of habituated and colour-banded drongos that are individually recognisable. Research has primarily focussed on the drongos deceptive use of false alarm calls, including mimicked alarms, to scare other species and steal their food. We have also explored the drongos role as a sentinel species within mixed species groups. They even sing a special ‘watchman’s song’ for other species, attracting them and allowing other species tospend more time foraging, and less keeping a lookout. Most recently, research has focussed on brood parasitism. Ironically drongos are themselves deceived by the African Cuckoo Cuculus gularis, and less frequently the Jacobin Cuckoo Clamator jacobinus, which lay their eggs in drongo nests. This affords an opportunity to explore competition over hosts between brood parasites. Furthermore, drongos and African Cuckoos appear to be locked in a tight co-evolutionary arms race as both show amazing matching variation in their egg pattern and coloration. In collaboration with Claire Spottiswoode, we have conducted experiments to explore whether such variation results from selection on drongos to reject dissimilar eggs. In addition, detailed knowledge of drongo life histories will enable investigation of the development of individual variation in drongo’s parasite defences.
Activities in 2016
- PhD student Amanda Bourne successfully trialled passive measurement of metabolism in Pied Babblers by feeding individuals prey items injected with doubly labelled water without having to directly handle individuals.
- PhD student Elizabeth Wiley collected her final season of data on the benefits of the monogamous pair bond at the start of 2016. The monogamous pair bond has rarely been investigated in a cooperative breeder, due to the traditional view that the importance of the group supersedes the importance of the pair bond. Lizzie's work, using both playbacks and observation, has revealed this is not the case.
- A new collaboration was forged between Susie Cunningham, Amanda Ridley, Claire Spottiswoode and Andrew McKechnie to understand the physiological effects of extreme weather events on Pied Babbler behaviour.
- A comprehensive long-term population analysis for Pied Babblers conducted by Elizabeth Wiley, revealed considerable sensitivities of the population to predicted future climate change.
- Amanda Ridley's TEDx talk on cooperation and conflict, featuring Pied Babbler research, was released online.
- PhD students Sabrina Engesser (U. Zurich) and James Westrip (U. Edinburgh) were awarded PhD degrees for their Pied Babbler research.
- An NRF grant application was successful for the collaboration of Susie Cunningham, Mandy Ridley, Claire Spottiswoode and Andrew McKechnie.
- New PhD student Amanda Bourne started conducting the physiological research on Pied Babblers.
- Pied babbler research was featured in the prime-time BBC program 'World's sneakiest animals' with presenter Chris Packham, and is available internationally on the Discovery Channel.
- Several papers on Pied Babblers were published, including on meaningful call combinations (Engesser et al. 2016. Proc. Natl Acad. Sci. USA) and nepotism (Nelson-Flower and Ridley, in press Biol. Lett.).
- A new Cooperative Breeding in Vertebrates was released by Cambridge University Press, featuring a chapter specifically on Pied Babbler research.
- Our research was presented at several international conferences.
- Ryan Olinger undertook a successful CB MSc project exploring the consequences of increasing temperatures for drongos. He showed that when it was hot, drongos foraged and provisioned their chicks less because of thermoregulatory constraints on their activity (see p.47).
- Rita Leal completed field data collection experimentally exploring coevolution between drongos and African Cuckoos.
DST-NRF CoE grant; Australian Research Council.
Assoc. Prof. Amanda Ridley (FIAO, UCT and UWA)
Dr Thomas Flower (FIAO, UCT and Simon Fraser University)
Dr Matt Bell (U. Edinburgh)
Dr Martha Nelson-Flower (U. British Colombia)
Dr Susie Cunningham (FIAO, UCT)
Prof. Claire Spottiswoode (FIAO, UCT and U. Cambridge)
Prof. Andrew McKechnie (U. Pretoria)
Dr Simon Townsend (U. Zurich)
Students: Sabrina Engesser (PhD Zurich); James Westrip (PhD Edinburgh), Elizabeth Wiley (PhD UWA); Amanda Bourne (PhD, UCT); Ryan Olinger (CB MSc, UCT)
Research assistants: Rita Leal, Sello Matjee