Not all birds have linnet heads. Several species even have a greater number of neurons in their brain than some primates. Humans clearly do not have the prerogative of intelligence, ethologist Louis Lefebvre shows us in Linnet heads? Innovation and intelligence in birdswhich is published by Éditions du Boréal.
Reading this fascinating popular work, we understand that expressions such as “bird brain” and “linnet head”, which are used in all languages to describe a stupid person, testify to the lack of understanding we have long demonstrated about the intelligence of birds.
These expressions probably appeared because “birds are small and have small heads and because there are some which, in fact, are not particularly clever, like ostriches, emus and chickens. But from the moment we started to really observe them and look at their brains, we realized that not only did birds have a structure equivalent to our cortex, but that certain species, like parrots and crows, had a greater number of neurons in this part of the brain than that of monkeys, whose bodies are larger,” underlines Louis Lefebvre, professor emeritus at McGill University.
One of the first observations of innovative behavior in birds which launched research in this area was that of titmice which managed to open milk bottles left by milkmen in the morning in front of house doors. First observed in 1921 in southern England, this behavior was later noticed across the country. It took 100 years before researchers demonstrated through a series of experiments in nature and in the laboratory that, when a titmouse had discovered how to access the cream on top of the milk, its innovation was then spread by cultural transmission, the birds imitating their congeners.
Mr. Lefebvre explains that the titmouse begins by pecking at the glass of the milk bottle, but that, sooner or later, like a good explorer, it then tries its hand at the cardboard or metallic paper cap, which it manages to tear off. or to drill. “The titmouse is skilled at searching for insects under the bark of trees, so it has adapted this behavior on the milk bottle. »
The bird that sees food behind a transparent barrier will first attack this barrier. Next, he must inhibit this behavior that is not working and look for alternatives. He also needs to understand the clues that the environment gives him when he tests his other attempts.
Louis Lefebvre was able to verify this phenomenon in the Barbados grackle, where McGill University has a research station. The researcher first observed innovative behavior in nature in this species, which notably steals dry pellets from dogs’ bowls and then dips them in water to soften them before eating them.
When his team presented grackles with a Petri dish with a clear lid and containing food, the birds first pecked the center of the lid. When they realized that this action had no effect, some began to prick the sides of the lid, which then began to move. Those who continued to act on this part of the lid ended up tipping the latter.
Mr. Lefebvre also tested the capacity for innovation of the sporophile (a cousin of Darwin’s finches) which, in the natural environment, grabs packets of sugar from restaurant tables and brings them to the nest, where it opens and eats their contents in complete peace of mind. He was able to observe during experiments that this exploratory species was also very successful in removing the lid from a Plexiglas box in which food had been placed.
In his book, Louis Lefebvre gives a multitude of examples of innovations demonstrated by various species of birds in nature. Many of these innovations involve the adoption of a new food source, often completely incongruous for the species in question, such as seabird gulls, which devour fast food from McDonald’s.
Others involve using a tool to access a coveted food item. For example, the woodpecker, a finch from the Galapagos Islands, uses a twig that it inserts into a crevice to retrieve insects lodged there. Some individuals of this species have even been seen using bark shavings as scrapers and removing leaves and side branches from a raspberry twig before inserting it into cracks. On Laysan Island, near Hawaii, curlews have been observed breaking albatross eggshells by hitting them with stones.
As a general rule, there is an innate basis for these innovations, but then there is generally added cultural transmission and individual learning where the animal practices and refines its execution, summarizes Mr. Lefebvre.
Comparisons between various avian species have shown that the most innovative birds are those with the largest brain size (relative to body size) and nidopallium, the equivalent of the prefrontal cortex in humans. They are also those whose pallium (cortex) contains the greatest number of neurons and NMDA 2B type receptors (sensitive to glutamate) on these neurons.
The champions of intelligence are undoubtedly the ravens and crows (the corvid family), more particularly the Caledonian crow. They are closely followed by parrots, among which the New Zealand kea stands out.
Ethologists Alex Taylor and Russell Gray designed ingenious experiments in which birds had to overcome very complex situations to reach their food. These experiments demonstrated that the New Caledonian crow is capable of planning its approach, which can include up to four steps, and of using more than one tool to achieve its ends. For example, he uses a first tool to obtain another which is otherwise inaccessible.
“In terms of intelligence, the great apes and the crows of New Caledonia are quite similar,” says Mr. Lefebvre. “The chimpanzee, however, is ahead of the crow for the diversity of contexts where tools are used in nature”, because it also uses them in “contexts of aggression” and “care of the body”.
Implicitly, this book shows us that “intelligence did not appear just once. It has manifested itself several times, independently. There are several groups [d’animaux] who, independently, have developed a little greater intelligence than the others. Even within the class of birds, there are several independent manifestations,” notes Mr. Lefebvre.
“Five million years ago, it was not obvious that the most intelligent animal today would be the descendant of apes. It could have been the descendant of the raven, because [le singe et le corbeau] weren’t that far from each other [en matière d’intelligence]. If we humans become extinct one day and crows survive, perhaps the kind of intelligence we have, which understands language and abstraction, will develop in a descendant of a corvid,” he says. -he.