Feathered can-openers

Lanzarote ravens are the first in the world to be scientifically observed opening cans with their beaks. We spoke to one of the scientists who helped make the discovery.

Photos pictured above (Flying raven taken by John Hanna | Raven eating gecko taken by Pablo Gustems)

Becky Dickinson is a bird lover who came to Lanzarote to volunteer with the Desert Watch project, which observes and protects birds in the El Jable desert region of central Lanzarote.

While out with Desert Watch, Becky was shown several discarded drinks cans with jagged holes in them and told that Desert Watch workers suspected had been opened by ravens. Becky decided to investigate further, and ended up with a project that would result in her Masters thesis and a scientific paper that has recently been published in the Birds journal.

The birdwatchers at Desert Watch had seen many ravens, but had not observed them opening cans, and Becky wondered if remote-controlled cameras would be a better way to confirm the theory that they were pecking the cans open.

But why do they do it? Becky and the Desert Watch volunteers believed they were after food. In Lanzarote’s hot, dry climate, insects, lizards, snails and even tiny shrews often climb into cans for shade, refuge or perhaps the traces of liquid inside. Many of them remain trapped.

To confirm the theory, the team left cans out deliberately, one in three of which contained meat and eggs. These turned out to be the ones that the ravens went for. The ravens were looking for ready-canned meals, and all they had to do was open them. To do so, they use their beaks to pierce and tear the thin aluminium.

Ravens and other crow species are highly intelligent. They have been observed to use tools, and Becky describes a project in Sweden where wild crows were “trained” to pick up cigarette butts in a town. Every butt the crows placed in a specialised machine dispensed a small amount of food, and the crows quickly started to clear the streets of cigarette-ends (although some problems occurred when they started stealing lit cigarettes from the hands of local smokers).

On Lanzarote, there was no sign of ravens using tools, although they will hold cans against rocks to steady them. But the fact that they have learnt to seek food in cans, which have only existed on the island for a few decades, shows that can-opening is specialised behaviour.

And it was the observation of this specialised behaviour that was the main focus of Becky’s paper. The fact that no one had seen ravens opening cans before suggested that humans may be interfering with their behaviour. and so many of the baited cans were monitored by remote cameras.

Ravens are vulnerable when on the ground and concentrating on a task, which is why they may not take risks if they know humans are around. For this reason, a remote-controlled camera is more likely to observe them behaving in a natural way.

The results of the study confirmed this, as well as recording raven activity that was previously unknown to science, but many questions remain unanswered about Lanzarote’s can-opening ravens.

Why, for example, do they seem to prefer beer cans over soft drink cans (they seem to have a special fondness for the local Tropical brew)? Becky suggests that other ravens often eat fermented fruit, and they may be more attracted to the smell of alcohol than sugary drinks.

Smell certainly seems to be an important factor in the choice of cans. The ravens were attracted to cans containing meat and eggs, and so it’s likely that the smell of small animals that have died in the cans may also attract them.

Another question is whether can-opening is learned behaviour passed on between a certain group of Lanzarote ravens, or is it more widespread? These, and other issues such as the effect of cans on local wildlife, are some of the avenues that Becky suggests could be explored in future research.

But in the desolate beauty of the El Jable region, where humans have developed a unique cultivation method for sweet potatoes and melons, it seems people aren’t the only clever and adaptable creatures.