If you think apes and dolphins are the only intelligent living beings on Earth besides humans, you probably haven’t looked very hard. Researchers are increasingly showing that bird species, especially crows and ravens, show clear signs of intelligence and even tool usage. Now, the smart animal club seems to have a new member: Eurasian jays.

These shy little birds are so intelligent that to confuse their prey during hunting they often mimic its sound. Moreover, just like humans, they have the ability to make savings — according to a new study, jays also save food for tough times. The new study reveals that Eurasian jays (Garrulus glandarius) can also demonstrate great levels of self-control.

Self-control is generally defined as the ability to avoid short-term benefits or immediate gratification for achieving better and greater rewards in the future. Some past studies highlight that self-control also reflects the level of intelligence in animals. Many such experiments that focused on analyzing self-control have already been performed for humans and apes.

However, not much is known about self-control in birds that are believed to be intelligent (such as parrots, crows, jays, and ravens). So, in order to find evidence related to intelligence and the ability to control urges in birds, a team of researchers at the University of Cambridge (UC) performed an exciting experiment with jays. 

Jays and the marshmallow test

The researchers adopted the famous marshmallow test, an experiment that was first conducted in the 1960s at Standford University to test self-control in children, and administered it to jays. During the original test, children were provided with a choice to take a small but immediate reward (a single marshmallow) or wait to earn a larger but delayed reward (two marshmallows). 

The authors used a similar paradigm except instead of offering marshmallows they offered different food items that jays commonly eat. They first worked out the birds’ preferences for the different food items. All jays that participated in the test preferred worms and their second preference differed from one another. Some jays preferred cheese, while others preferred bread. 

During the experiment, the jays were given a choice to choose between two food items; the less preferred food item, which was immediately available, or the most preferred food item (worm) which was only available after a delay. The researchers used drawers that were marked with different shapes to train the birds to learn about the different types of food available in them (i.e. one drawer open immediately and the other drawer baited with the worm only opened after a delay). 

They tested a range of different delays (i.e., 5, 10, 20, 30, 40, 60, 80, 160, and 320 seconds) and found that all the jays were able to delay gratification and wait for a better reward. However, the performance of the birds varied from one another. For instance, while two jays named Dolci and Homer respectively could resist for only 20 seconds, another bird called JayLo waited for more than five minutes to get the mealworm.  

First author and Darwin Research Fellow at UC, Dr. Alex Schnell was thrilled to see the results, writing in the paper: 

“It’s just mind-boggling that some jays can wait so long for their favorite food. In multiple trials, I sat there watching JayLo ignore a piece of cheese for over five minutes – I was getting bored, but she was just patiently waiting for the worm.”

What do these test results mean?

In an email exchange with ZME Science, Dr. Schnell also highlighted that results of the 1960s test in children showed that individuals who perform well on the marshmallow test also perform well on tests of general intelligence such as IQ tests and academic tasks. This pattern has also been demonstrated in diverse taxa including chimpanzees and cuttlefish. Now through their current study, for the first time, a link between self-control and intelligence has been shown in birds. 

Still, there are some limitations to the study, in particular the small sample size. Only ten jays willingly participated in this study and they found individual variations in their ability to exert self-control and variation in their scores on a separate series of intelligence tests. However, the researchers claim that the relationship between these two data sets was significant and their effect size was large even with their small sample size.

“Our research provides strong evidence that self-control plays a key ingredient in what it means to be intelligent. Given that we see this strong correlative pattern in diverse animal species (i.e., chimpanzees, cuttlefish, jays), it highlights the cognitive similarities that we share with other animal minds,” Dr. Schnell told ZME Science.

The study is published in the journal Philosophical Transactions of the Royal Society B.