Numerical abilities play a fundamental role in survival by enabling animals to assess resources and make adaptive decisions. Among these, numerical discrimination, the capability to distinguish between larger and smaller numerosities, is highly studied. Numerical discrimination can be solved using two strategies: the absolute, selecting a specific numerosity, or the relative, identifying the larger or smaller one. While numerical discrimination is shared across species, the strategies used to address it vary: humans and fish employ a relative strategy, while honeybees use an absolute one. It remains unclear which strategy birds prefer, especially if they have only minimal numerical experience. Here, we investigated whether 3-d-old chicks adopt absolute or relative numerical discrimination. During rearing, chicks associated a numerosity with food. At test, we assessed whether they used an absolute or relative strategy. At the group level, no significant preference emerged, regardless of whether higher or lower numerosities were associated with food. However, at the individual level, chicks displayed significant preferences that could not be explained by stimulus novelty or physical variables (e.g., overall area). Flexibility in numerical discrimination may reflect an evolutionary adaptation or developmental feature. Retaining multiple strategies, and refining one through environmental interactions, could benefit young animals.

Read the full article in the Journal of Animal Science.