Robins can count

The South Island robin (Petroica australis australis) is a worm eating machine. It’s also a worm caching machine: robins are known to cache their food (and to steal from one another’s caches). Experiments conducted by Victoria University biologists suggest that these robins can also count. A video on YouTube shows an experiment carried out where some robins were shown a single mealworm being put into a hole in a stick. The robins would retrieve the mealworm and go back to the researcher, hoping for more mealworms, doing their usual, friendly robin thing. Then, some robins were shown two mealworms being put into the stick, but the researcher concealed one beneath a ‘trapdoor’. The robin in the video saw two mealworms and expected two mealworms. When it found only one mealworm and its searches could not reveal the second, it began scolding the researcher. ‘Where is my second worm, you stealer of worms!’ This research suggests that robins can distinguish different numbers of prey items to a higher number of items than any other untrained wild animal.