A new study conducted in Canada among four colonies of Delaware gulls (Larus delawarensis) has shown that gulls are birds may be more intelligent than previously thought.

According to scientists these birds can succeed in what is known as the rope-pull test.

In its publication on the site Science AlertThe researchers reveal that they placed a string on the floor connected to a Petri dish with a piece of sausage, which was inside a clear plastic box. With only a narrow slit in the box, the birds had to pull on the string to get the snack out.

"Before that, these wild gulls had to get used to the presence of the box," the scientists tell us and continue, "the team isolated specific nests in the wild and placed an empty box next to them, in this case, the box was empty, but a piece of sausage was placed outside, near its slit."

According to the study, after doing this four times, the scientists placed a sausage with a string inside the box. Another sausage was placed outside again, very close to where the string was, to see if the birds would investigate the new material.

"Those steps being completed, three attempts of the actual rope-pull test were then made. In 93 nests, the researchers counted a total of 138 gulls with parental responsibility, which returned to the nests to investigate the box. Of these, 104 attempted to solve the test in at least one of the attempts," the research reveals.

However, in all four colonies, there were gulls that were able to solve the test. Of all 104 attempts, 25% succeeded by taking the sausage out of the box to eat, and 21% accomplished this on the first attempt.