DRBNats 9 December 2022
Ask people what their favourite Australian bird is, and many will answer “the maggie”, the Australian Magpie. Indeed, even those who profess no interest in birds can almost always name this one. But for all their ubiquitous popularity, there’s a lot we don’t know about them, like how they organise their social structure, develop their intelligence and cope with the stresses of their environment.
Associate Professor Amanda Ridley, Principal Investigator, Western Magpie Research Project, gave members of the DRB a most interesting account of the research she and her PhD students are conducting into the lives of the Australian Magpie.
Wild magpies (Cracticus tibicen) commonly live well into their 20s and use their long lives to develop high levels of intelligence and complex social structures within their groups. In Western Australia, the subspecies (dorsalis) have developed high levels of cooperative breeding (almost unknown in Eastern States subspecies) whereby within a group, most adult females attempt to breed, and those that fail often end up becoming helpers to other females. Extra-pair mating is the norm, so much so that it is usual for more than 80% of the young in a nest not to be fathered by the male of the pair who built the nest and raised the young.
Group sizes vary a lot. In the west, these can range from 3 to 16 birds, and it turns out that the size of the group (and hence the complexity of the necessary social interactions) strongly influences the development of the intelligence of individual birds; in other words, larger groups contain smarter birds. Intelligence was measured in habituated wild birds by presenting them with food items visible within a Perspex container with a counter-intuitive entry portal. The birds were assessed on how quickly they could work this out and remember it for next time. Another test involved the birds having to remember under what colour of the lid a food item was hidden, and then, having understood that they had to unlearn it and reverse their memory when the rules were changed, and the “other” colour was used.
Environmental stress (high temperature in this case) has a marked influence on the expression of intelligence. Up to ambient temperatures of about 30oC performance was practically uniform, then showing a slight falling off up to about 33o, after which it “fell off a cliff”. The graph we were shown took a remarkably steep nose-dive after this temperature, so we can confidently say that high temperatures are not suitable for magpies – the decline in performance seems to mirror that seen in children stressed by over-hot classrooms.
Our thanks to Mandy (and her students) for a fascinating insight into the lives of Australia’s favourite bird.
Mike Green