Overview
- Researchers from the University of Barcelona, University of Leipzig and the Max Planck Institute tested four giraffes at Barcelona Zoo using hidden-addition and subtraction trials that involved moving carrot pieces between covered containers.
- In addition trials the giraffes chose the container with the larger total 68% of the time, a rate the authors said exceeded random chance.
- The animals failed subtraction trials, selecting at rates consistent with random choice when pieces were removed rather than added.
- Follow-up controls showed two giraffes likely relied on a human-touch cue when choosing, while the other two maintained the same success rate after those cues were removed.
- The authors warn the results may reflect judging bulk or simpler cues rather than counting, and they call for larger samples and tighter controls to determine how broadly the findings apply to the species.