Assessing Small and Large Numerical Discrimination in Three Breeds of Domestic Chicks (Gallus gallus)

Extensive evidence suggests that non-human animals, including domestic chicks, master numerical abilities. Studies have shown that newly hatched chicks (up to 5 days old) have sophisticated numerical abilities among which is the ability to discriminate quantities; studies comparing both small and large number sets have already been conducted with chicks. Studies suggest that animals discriminate between quantities using either the Object File System for smaller numerosities (up to 3-4), and the Analogue/Approximate Number System for larger numerosities (5 and larger). In this study we assessed whether newly hatched chicks of the breeds Ross308, Gallina Padovana, and Red Junglefowl perform better in small-number (i.e. 1 vs. 2) or large-number (5 vs. 10) numerical discrimination tasks and found that there were no significant differences. Chickens have also long been domesticated and artificially selected for production traits (e.g., faster growth) which may have led to changes in the cognitive abilities in comparison with their wild ancestors. Previous research suggests that the domesticated breeds may have inferior numerical abilities compared to their wild counterparts due to a number of reasons, which may be interconnected. First, domesticated chickens may not need this type of abilities in captivity, where over generations, the trait, not being selected for, has declined. Second, it is possible that domesticated chickens allocate more resources toward production-related traits, potentially at the expense of cognitive functions. A secondary question addressed in this project is whether domestication and selection for production traits have had any significant impact on the chicks’ numerical discrimination abilities. We found that there were no significant differences in the performance of different breeds. However, chicks of an ancestral breed and a traditionally cultivated breed did perform better in the first test trials than chicks of a highly domesticated breed. The general performance in discrimination task was compared between Ross308, Gallina Padovana, and Red Junglefowl.