Main Club 5 November 2021
Our speaker was Dr Amanda Ridley, from the Centre of Evolutionary Biology at the University of WA. Mandy has been conducting behavioural ecology research for the last 22 years, studying Babblers in the Middle East and in the Kalahari, before setting up a Western Magpie Research Project at UWA. Her topic was cooperation, competition and climate change in Western Australian magpies.
Why do animals cooperate? It’s a question that has motivated much of Mandy’s research. Cooperation seems to run counter to the Darwinian idea that individuals have to pass on as many of their own genes as possible.
Sociable Weavers in the Kalahari build a huge communal nest, and only the dominant male and female will breed, while the others share the jobs involved in nest-building and feeding and protecting the young. Most of them don’t pass on their genes at all. The division of labour helps the survival of the group, and it works better in bigger groups. Some birds that don’t have chicks even kidnap the young of others in neighbouring groups and raise them as their own. This may help survival of the group and the species.
Magpies in Western Australia live in groups. These birds are very different from the group-living Babblers in Africa. Most magpies in WA try to breed, and some help to raise the young of others. But only some of the non-breeding birds help. This doesn’t fit the norm of cooperative breeding, and it doesn’t seem to have survival value. However, the Social Intelligence hypothesis proposes that living in a group will raise the intelligence of the members, and more so in a large group. So Mandy tested 80 magpies by giving them a variety of cognition tests. Testing was done in the wild – not in the lab. On re-testing, the repeatability was 97%, suggesting that the tests were valid. And tasks were varied each time, so any improvement in skills was not because of learning the tasks.
Results showed that the bigger the group of magpies, the more the birds acquired and responded to information. And even after groups had split, those that had been in bigger groups for longer were more intelligent. Mandy suggests that the more social interactions a bird has with other birds, the more its intelligence will improve, and its enhanced intelligence will increase its chance of survival.
Australian magpie populations are in decline, and Mandy wanted to find out whether heat stress may be the cause. So she developed ways to measure heat stress in magpies without catching them, using thermal imaging. She found that heat stress caused a dramatic decline in cognition. Her research suggests that a warming and drying climate is a major factor in the decline.
It surprised me to hear that among magpies in the eastern states there is less cooperation and they don’t form groups as ours do in the West.
Mike Gregson