# Counting Chicks

## Research shows that, at a very young age, chickens are capable of basic math.

Reading Time: 4 minutes

*By Laura Garnham*

Besides the well-known saying “don’t count your chickens before they hatch,” we don’t really associate chickens with numerical, let alone mathematical, abilities. Surely, such abilities are unique to humans and, maybe, the animals we typically consider intelligent, like great apes, elephants, dolphins, and crows. Chickens capable of doing even basic math? The idea seems absurd, yet, recent research suggests that, even at a very young age, they may indeed be capable of this. Read on to find out more about the numerical abilities discovered in chickens so far, and the research behind these discoveries.

To begin with, can chickens count? It seems they can, at least in some situations. In one study^{1}, researchers presented five-day-old chicks with a row of 10 identical holes and rewarded them for approaching one particular hole. The chicks became rather good at selectively choosing the hole they were rewarded at. The researchers wondered if the chicks might be choosing the correct hole in the row by counting holes up, or down, the row, or by using spatial cues from the room around the row. Therefore, they rotated the row of holes so that the chicks would make the wrong choice if they were using spatial cues. The chicks still chose the correct hole, and so, the researchers concluded that they were counting the holes to choose the correct one.

If chickens can count, might they be able to distinguish between different quantities? It looks like they can indeed do this, even in their first few days of life, as researchers found when they rewarded chicks for selecting cards with certain amounts of symbols, up to 14, printed on them ^{2}^{,}^{3}. To be sure the chicks chose cards based on the number of symbols present and not, simply, how much of the card’s surface area was covered by the symbols, the researchers used cards in which the number of symbols increased, while the surface area they covered stayed the same.

As well as distinguishing between quantities, chicks may have a concept of larger than/smaller than and mentally rank numbers from left to right in terms of size, a method used by many humans. In one study^{4 }, researchers rewarded three-day-old chicks for approaching cards with a certain number of symbols printed on them. Following this, they showed the chicks two sets of two identical cards, one set after the other. In one set, both cards had fewer symbols than the chicks were used to. In the other set, both cards had more symbols than the chicks were used to. When the number of symbols on the cards was fewer than they were used to, the chicks preferred to approach the card on to their left. When the number of symbols on the cards was more than they were used to, the chicks preferred to approach the card to their right. The researchers concluded that the chicks associated smaller numbers with their left and larger numbers with their right.

So, it seems that chicks can count, distinguish between different quantities, and have a concept of smaller and larger, but can they do any sums? One study suggests they might be able to^{5}. In this study, three- to four-day-old chicks watched objects they had imprinted on being hidden behind two barriers. Next, they watched these objects being moved between the barriers. Following this, the researchers allowed the chicks to go behind one of the barriers. The chicks were very good at choosing the barrier which had the largest number of objects behind it (they naturally have an innate preference for being with as many of the objects they have imprinted on as possible). To know which barrier hid the largest number of objects, the chicks must have been keeping track of how objects were taken away from the objects behind one barrier and added to the objects behind the other barrier, that is, they were doing simple sums.

Chicks also appear to have an, at least rudimentary, grasp of geometry. At only three days old, they can determine what a shape is, for example, triangle or square, even if part of it is covered^{6}. In addition, they show an innate preference for shapes that make sense, choosing, when only one day old, without any training, the image of a possible 3D shape when presented with this and the image of an impossible 3D shape^{7}. They can also distinguish between different lengths and angles. In one study^{8}, researchers rewarded chicks for going to a certain location in an arena, in which the walls were different lengths and connected by different angles. If the arena was re-orientated without the chick inside, the chick still went to the rewarded location once returned to the arena, navigating by, the researchers assumed, the different lengths of, and angles between, the arena walls. Chicks were able to do this at only four days old.

Overall, chickens may be more mathematically capable than we usually give them credit for. The experiments discussed in this article are relatively simple, so if you are feeling inspired to test whether your chickens have the skills discussed here, chances are you can do so. These mathematical abilities may, initially, seem quite simple. However, the chicks that participated in these studies were all less than one week old. Whether, if chickens, like us humans, develop better numerical and mathematical abilities with age remains to be seen. Hopefully, future research will focus on whether adult chickens can perform more complex mathematical feats. Perhaps the first question to answer should be: can they count themselves?

**References:**

- Rugani R and Regolin L (2007). Rudimental Numerical Competence in 5-Day-Old Domestic Chicks (Gallus gallus): Identification of Ordinal Position. Journal of Experimental Psychology: Animal Behavior Processes 33:21–31
- Rugani R, Regolin L, Vallortigara G (2008). Discrimination of small numerosities in young chicks. Journal of Experimental Psychology: Animal Behavior Processes 34: 388–399
- Rugani R, Vallortigara G, and Regolin L (2013). From Small to Large: Numerical Discrimination by Young Domestic Chicks (Gallus gallus). Journal of Comparative Psychology 128: 163–171
- Rugani R, Vallortigara G, Priftis K and Regolin L (2015). Number-space mapping in the newborn chick resembles humans’ mental number line. Science 347: 534-536
- Rugani R, Fontanari L, Simoni S, Regolin L and Vallortigara G (2009). Arithmetic in newborn chicks. Proceedings of the Royal Society B: Biological Sciences 276: 2451-2460
- Regolin L. and Vallortigara G (1995) Perception of partly occluded objects by young chicks. Perception & Psychophysics. 57: 971–976.
- Regolin L, Rugani R, Stancher G, Vallortigara G. (2011) Spontaneous discrimination of possible and impossible objects by newly hatched chicks. Biology Letters 7: 654–657
- Tommasi L, Polli C. (2004) Representation of two geometric features of the environment in the domestic chick (Gallus gallus). Animal Cognition 7: 53–59

*Originally published in the February/March 2021 issue of Backyard Poultry and regularly vetted for accuracy.*