Do Animals Use Tools?

Spoiler alert: Yes, many wildlife species—from brainy birds and mammals to fish and even insects—use tools to get the job done

By Asher Elbein
Wildlife Science
Jun 27, 2024

A chimpanzee wields a stick to forage for insects in a tree cavity in Guinea. Chimps provided the first well-accepted examples of tool use among nonhuman animals. (Photo by Cyril Ruoso/Minden Pictures)

IN 1938, OFF THE COAST of Monterey County, California, a naturalist named Edna Fisher was busy observing the activities of a rare “herd” of nearly 100 southern sea otters—at the time nearly extinct—when she noticed an odd behavior. Some of the animals would dive to the bottom of the sea, surface carrying a stone and then use the stone to crack open mussels. The following year, Fisher reported in the Journal of Mammalogy that the Monterey otters were using tools, a behavior previously thought to be the sole province of humans.

For decades, Fisher’s paper was ignored by scientists. It wasn’t until 1971 that primatologist Jane Goodall’s field research with chimpanzees provided the first widely read, well-documented cases of tool use by nonhuman animals: chimps that stripped leaves off a twig then used the stick to fish termites from their nest. In response to Goodall’s observations, her supervisor, anthropologist Louis Leakey, famously remarked that “now we must redefine man, redefine tools or accept chimpanzees as humans.”

Since then, scientists have recognized tool-using behavior in dozens of animal species, says Rob Shumaker, CEO of the Indianapolis Zoo and co-author of the 2011 book Animal Tool Behavior. Tools are employed for far more than gathering food, he says. They can be used to build nests (tailorbirds that sew nests from leaves and spider silk, for example), for defense (octopuses that carry around coconut shells to hide in) or even to enhance comfort (bears that pick up rocks to scratch themselves or elephants that use branches to shoo away flies).

All such behaviors share a basic principle: An animal uses an object in the environment as an extension of its own body in order to manipulate things around it. Beyond that, however, the picture gets complicated. “The level of cognition involved in tool use seems to differ quite substantially between different animal groups,” says Volker Deecke, a biologist at England’s University of Cumbria who’s written about tool use in unexpected species. Some animals seem to do it instinctively, he says. Others are adaptable and experimental, picking up tool usage by trial and error or by observing other individuals.

“Frequently, people assume that tool use is associated with cognitive ability, but it absolutely is not necessarily an indicator of intelligence or cognitive complexity,” Shumaker says. As the ranks of confirmed tool-using critters have grown steadily since the early 20th century, the world now abounds with intriguing examples of both expected and surprising animals. Here are just a handful.

An image of a Southern sea otter breaking open a clam.

Off the California coast, a sea otter (above) breaks open a clam by bashing it against a rock the animal has placed on its belly. In Brazil, a black-striped capuchin (below) also uses a rock as a tool to break open a palm nut.

Beyond the hominid family

Homo sapiens’ closest animal relatives, chimpanzees, remain the most famous animal tool users. But an array of other primates, including gorillas and brown capuchin monkeys, also employ tools. Primates use both wood and stone implements for a diversity of purposes, including hunting, gathering food and water, and self-defense.

Primates, especially apes, for many years were considered to be the only mammalian tool users. Yet scientists have reported dozens of nonprimate mammals that use tools, from pigs and horses to mongooses and badgers.

An image of a black-striped capuchin using a rock as a tool to break open a pine nut.

Some of the most accomplished mammalian tool users are still found offshore: the southern sea otters that were first documented employing stone tools more than 80 years ago. For the past 17 years, Jessica Fujii, sea otter program manager at the Monterey Bay Aquarium, has been observing the tool-use behavior of these animals. She says otters eat a wide variety of hard-shelled invertebrates—such as clams, mussels and marine snails—some too tough even for an otter’s powerful jaws. But they aren’t too tough for rocks. As the animals dive to the bottom for prey, they often select a stone at the same time, Fujii says. Back on the surface, they place the rock on their chest and bash their prey against it like an anvil or, occasionally, reverse positions to use the rock as a hammer. While some naturalists have claimed that otters keep a favored rock for an entire lifetime, she says they typically just pluck up rocks on an as-needed basis—though individuals may hold on to distinctively colored rocks for the length of a foraging session, tucking the stones into pockets under their arms. “That does show a sense of planning,” Fujii says.

Recently, she and her colleagues discovered that otters’ use of tools can leave long-term traces on the environment that are recognizable using archaeological methods. In a 2019 paper published in Scientific Reports, they describe a 10-year study at a single site off the California coast where otters have learned to use stationary rocks as anvils to open mussels. The researchers say the animals’ behavior has led to consistent patterns of wear on the rocks accompanied by characteristic accumulations of broken mussel shells.

“By combining behavioral observations and archaeological survey methods, we show that sea otters have created a distinct, recognizable archaeological record,” the scientists write. They add that their study—the first to apply statistical methods of measuring wear on stone, common in research on human stone-tool use—“raises the potential for discovery of similar sea otter pounding sites” in locations where the animals are no longer found. Classified as threatened under the Endangered Species Act since the 1970s, southern sea otters today occupy just a small fraction of their historical range.

An image of four burrowing owl chicks standing at the edge of their burrow in evening light.

Burrowing owl chicks gather near their burrow in Wyoming (above). To attract a favorite prey, dung beetles, some owls collect and place the dung of other animals outside their homes. A brown-headed nuthatch perches on a tree in Texas (below). To find food, the birds break off bits of wood then use the tools to pry up tree bark and expose insects that are hiding beneath.

Rethinking bird brains

After researchers recorded New Caledonian crows fashioning utensils out of pandanus leaves in the mid-1990s, scientists focused efforts to discover additional tool-using birds on well-known opportunistic and curious species such as crows and parrots. Yet tool use is found in at least 33 bird families, from warblers to gulls and herons.

Some of these birds are known for setting bait for prey, with seven heron species, for example, dropping tempting food morsels in the water to attract fish. One unexpected practitioner of this technique, the burrowing owl, is found in much drier ecosystems hunting very different prey. The birds inhabit grasslands, deserts and other open habitats across much of the high plains and western United States, extending north into Canada and south into Mexico. Relict populations hang on in sandy, open prairies (including golf courses and housing developments) in Florida.

Unlike other owls, burrowing owls are active during the day and spend most of their time on the ground, usually around burrows excavated by other species. They accessorize these homes with an unusual feature: dung from nearby mammals, including horses and dogs.

How to explain such a strange behavior? Before retiring from the University of Florida in 2011, ornithologist Doug Levey regularly led classes out to a burrowing owl colony to examine the birds’ pellets. Picking apart the leavings, the students noticed that pellets commonly contained the remains of dung beetles, ordure-collecting insects up to an inch long. That led them to wonder if the owls were deliberately luring in dung beetles attracted to their odd burrow decorations. Or might they just be trying to hide the scent of their eggs from predators with something smelly?

To test both possibilities, Levey divided up a set of occupied owl burrows, leaving dung outside half and removing it from the other half. In their resulting paper, published in Nature in 2004, he and his team reported that dung had no effect on potential egg thieves. The owls whose dung they’d stolen, however, immediately went out to collect more—and the birds who’d kept their dung had eaten a higher number of dung beetles.

The finding gelled with one aspect of the owls’ behavior: their tendency to be active not long after sunrise, around the time when dung beetles are most likely to show up. The owls, Levey says, are “actively fishing for dung beetles during the time of day when the dung beetles are most active.”

In forests of the U.S. Southeast, another bird, the brown-headed nuthatch, actually creates its own tools and carries them along to help procure food. In the 1990s, researchers working in two Florida slash-pine woodlands reported that the tiny, squeaky-voiced songbirds would break off flakes of wood from trees then use them as levers to pry up pieces of bark on other trees. That action exposed tasty insects hiding beneath. Some birds reused the same tool multiple times, flying short distances with it clutched in their beaks.

More recently, Mary Mack Gray, an ecologist formerly with the Tall Timbers Research Station and Land Conservancy in Florida, discovered that this tool-using habit begins early. In a 2016 paper in Southeastern Naturalist, she and her colleagues described observing young nuthatches—some only 2 months old—using bark tools and experimenting with different objects as well. “The juvies seem to be picking it up fresh out of the nest, so to speak,” likely by observing other nuthatches, Gray says.

An image of weaver ants working to build a nest, using larva to produce silk.

A weaver ant (above) in Malaysian Borneo uses silk produced by its larvae to glue together leaves and build a nest. In California, a northern Pacific rattlesnake (below) hides in the grass awaiting prey. To improve chances of a clear strike, some snakes will use their heads to push aside vegetation.

No hands but still handy

Understandably, animals that we consider “smart,” such as birds and mammals, and especially primates, have received most of the attention from scientists studying tool use. Still, a growing number of studies have provided clear evidence of the behavior among a range of more-unexpected species, including fish and even insects.

Some of the most adept insect tool users are ants. Two species of funnel ants, for example, employ sand grains, leaf fragments and other debris to collect and carry liquid food back to their nests. Weaver ants use their larvae to produce silk that glues together the leaves from which they weave their nests. And bicolored pyramid ants pick up small stones to drop down the nest entrances of other desert ant species, blocking the insects from exiting and thereby reducing competition for food.

It turns out an animal doesn’t even need limbs to manipulate the world around it. Take the northern Pacific rattlesnake, an elusive and patient hunter that frequents oak woodlands in search of ground squirrels. As part of her Ph.D. research, Bree Putman, a specialist in reptile behavior at California State University, San Bernardino, tracked the snakes using radio telemetry to better understand how they hunt. The snakes spend long periods coiled up in grass near rodent trails, trusting their cryptic coloration to hide them as they await the approach of prey. Once Putman had located the hidden snakes with telemetry, she set up monitoring cameras to record their activity then left them to it.

An image of an adult Northern Pacific rattlesnake in tall grass.

While reviewing footage from the 18 snakes in the study, Putman and her colleagues noticed two that exhibited an odd behavior. They made “these weird jerking head movements that I had never seen before,” she says. Because rattlesnakes, as ambush predators, avoid movements that would give away their positions and alert prey, the researchers assumed the head jerks had to have some benefit. In a 2015 paper published in The Southwestern Naturalist, Putman and her team concluded that the snakes were pushing aside bits of vegetation with their heads to set up a clear strike.

Putman’s team didn’t find any differences between sites where the snakes kept still or apparently tried to reshape the terrain in their favor. “We don’t know what’s actually going through their head, or if they’re making the best decision,” Putman says. “They make mistakes too!”

What the snakes were doing does not fit the scientific definition of tool use but rather “habitat manipulation,” write the researchers. But Putnam thinks it’s not far off. “As humans, we just don’t view reptiles and especially snakes as being conscious or smart or feeling things,” she says.

The work also underscores the message that complex behavior is not simply a habit of big-brained species. “We only tend to look for higher cognitive function in animals we perceive as intelligent,” Deecke says. “So, we’re constantly being surprised by what animals we wouldn’t traditionally consider intelligent can do.”

Asher Elbein is a nature and culture reporter in Austin, Texas.