A team of researchers from the University of Western Australia, in collaboration with a colleague from the University of Exeter, have discovered that as female southern pied babblers age, they produce more offspring despite losing some cognitive abilities. The group tested the cognitive abilities of the birds as they aged in the wild in their study. The study was published in the journal Proceedings of the Royal Society B. The study also noted their reproduction levels.
Southern pied babblers are small black-and-white birds that live in Africa’s dry savannahs. The researchers wanted to learn more about their cognitive abilities as they aged in this new study. Researchers captured, studied and released multiple generations of birds to determine their cognitive levels over time. They also counted how many chicks each of the females produced.
The researchers discovered that the cognitive levels of the birds peaked early and then began to decline in females as they matured. They also discovered that as the birds’ cognitive abilities deteriorated, they produced an increasing number of chicks.
The researchers believe their findings point to a tradeoff. Cognitive abilities necessitate a significant amount of energy. To survive, the birds must conserve energy. One way to do so is to reduce the energy requirements of the brain. This increases the amount of energy available for egg production and chick rearing. The researchers also point out that females of the species compete with other females for breeding rights. This requires a lot of energy but not much brain power.
In contrast, the researchers discovered no changes in male cognitive abilities as they aged. They also discovered no evidence that birds living in larger groups performed better on cognitive tests than those living in smaller groups. The researchers also said that females who had less cognitive decline than the others had fewer chicks.
More information: Camilla Soravia et al, General cognitive performance declines with female age and is negatively related to fledging success in a wild bird, Proceedings of the Royal Society B: Biological Sciences (2022). DOI: 10.1098/rspb.2022.1748