MSc Student
Supervisors: Sabine Tebbich*, Alice Auersperg**
* Dept. of Behavioural and Cognitive Biology, Faculty of Life Sciences, University of Vienna
** Messerli Forschungsinstitut, Veterinärmedizinische Universität Wien
Abstract
The capacity of animals to evaluate weight cues and differentiate between lighter and heavier objects is a fundamental aspect of Optimal Foraging Theory (Pyke, 1984; Werner & Hall, 1974).In tool-using species, this ability extends to tools utilized during foraging activities. While the majority of research on weight discrimination has focused on primates—highlighting their advanced cognitive abilities—recent studies have revealed remarkable capabilities in Goffin's cockatoos (Cacatua goffiniana). These birds, known for their sophisticated tool use and manufacture, not only outperform apes in weight discrimination tasks but also demonstrate a refined ability to integrate weight assessment into practical decisions. For instance, Goffin’s cockatoos require 80% fewer trials than apes in an exchange paradigm task (Lambert et al., 2021; Schrauf & Call, 2009) and prefer transporting lighter objects over heavier ones in both walking and flying modes, although they show no difference when presented with proportionally or disproportionately weighted objects (Adelmant et al., 2024).
This study investigated how the weight distribution of an unbalanced stick tool influences the insertion techniques of Goffin's cockatoos in a stick-tool-box task. Using 10 adult cockatoos from the Goldegg Lab in St. Pölten, the research aimed to assess whether the birds learn to preferentially insert the lighter end of an unbalanced stick—an energetically less demanding approach (Prediction 1)—and whether their insertion techniques adapt to account for the stick’s weight imbalance (Prediction 2). The experiment built on the birds' familiarity with the setup from previous experiments (Osuna-Mascaró et al., 2023), enabling detailed analysis of their individual problem-solving styles.
The results revealed a significant group-level preference for lighter-end insertions, as predicted, alongside intriguing individual-level variations in tool-handling techniques. These findings underscore the interconnected nature of technique adaptation and weight discrimination rather than treating them as separate processes. The cockatoos' heightened sensitivity to weight distribution, combined with their ability to evaluate and adapt to various tool properties such as balance and handling, highlights a nuanced interplay between these factors. This sensitivity likely has ecological relevance, as optimizing tool use for weight and balance could enhance foraging efficiency and overall fitness.
References
Adelmant, C., Osuna-Mascaró, A. J., Folkertsma, R., & Auersperg, A. M. I. (2024). Goffin’s cockatoos use object mass but not balance cues when making object transport decisions. Scientific Reports 2024 14:1, 14(1), 1–10. doi.org/10.1038/s41598-024-76104-7
Lambert, P. J., Stiegler, A., Rössler, T., Lambert, M. L., & Auersperg, A. M. I. (2021). Goffin’s cockatoos discriminate objects based on weight alone. Biology Letters, 17(9). doi.org/10.1098/RSBL.2021.0250
Osuna-Mascaró, A. J., O’Hara, M., Folkertsma, R., Tebbich, S., Beck, S. R., & Auersperg, A. M. I. (2023). Flexible tool set transport in Goffin’s cockatoos. Current Biology, 33(5), 849-857.e4. doi.org/10.1016/J.CUB.2023.01.023
Pyke, G. H. (1984). Optimal foraging theory: a critical review. Annual Review of Ecology and Systematics. Vol. 15, 523–575. doi.org/10.1146/ANNUREV.ECOLSYS.15.1.523
Schrauf, C., & Call, J. (2009). Great apes’ performance in discriminating weight and achromatic color. Animal Cognition, 12(4), 567–574. doi.org/10.1007/S10071-009-0216-1
Werner, E. E., & Hall, D. J. (1974). Optimal Foraging and the Size Selection of Prey by the Bluegill Sunfish (Lepomis Macrochirus). Ecology, 55(5), 1042–1052. doi.org/10.2307/1940354
