Animal attacks on humans are rising, with one large U.S. study finding a 6.3% annual increase in animal-related fatalities between 2018 and 2023. Most attacks follow predictable patterns: a surprised animal defending itself, a mother protecting her young, or a wild animal that has lost its natural fear of people. Understanding why animals attack, which species pose the greatest risk, and how to respond can make the difference between a close call and a serious injury.
Why Animals Attack
The vast majority of animal attacks are defensive. An animal that feels cornered, startled, or threatened wants one thing: distance. A bear that stumbles into a hiker on a trail will typically try to knock the person down, neutralize the perceived threat, and flee. It isn’t hunting. It’s scared. The same applies to most snakes, which bite when stepped on or cornered, and to dogs, which lash out when they feel trapped or when someone enters their space too quickly.
Beyond surprise encounters, there are three other common triggers. First, natural protective aggression: females guarding their young or any animal defending a food source. These situations are largely avoidable if you give animals and their resources a wide berth. Second, food conditioning: animals that have learned to associate humans with food (from campsites, garbage bins, or intentional feeding) gradually lose their fear of people, which makes conflict far more likely. In one study of coyote attacks, humans had previously been feeding coyotes in the area in a full third of cases. Third, human provocation, often from people trying to take photos with wildlife or hand-feed animals in national parks. These encounters frequently end with the animal being euthanized.
Climate change and urban sprawl are accelerating all of these dynamics. As habitat shrinks and food sources shift, wildlife and humans cross paths more often, in more places, and with less buffer between them.
The Numbers: Which Animals Are Most Dangerous
Globally, snakebites kill more than 100,000 people every year, making venomous snakes by far the deadliest animals to humans on the planet. In the United States, the picture is more contained: 7,000 to 8,000 people are bitten by venomous snakes annually, but only about five die. The more pressing concern for survivors is lasting damage. Among people bitten by rattlesnakes, 10 to 44 percent experience permanent injuries. Copperheads, cottonmouths, and coral snakes round out the four venomous groups found in the U.S.
Wild mammal encounters in the U.S. result in roughly 3,000 nonfatal adverse incidents and fewer than five deaths per year, excluding small rodents and bats. Between 2018 and 2023, 26 people were killed by bears in North America: 15 by brown (grizzly) bears, eight by black bears, and two by polar bears. During the same period, only two fatal cougar attacks were documented.
Shark attacks draw outsized attention relative to their frequency. The International Shark Attack File confirmed 65 unprovoked shark bites worldwide in 2025, consistent with the five-year average of about 61 per year. Another 29 bites were classified as provoked, meaning the person was handling, feeding, or otherwise interacting with the shark before being bitten.
Warning Signs Before an Attack
Animals rarely go from calm to attacking without warning. Recognizing the signals gives you time to back away before a situation escalates.
Dogs display a reliable sequence of stress cues before biting: lip licking when no food is present, yawning when not tired, turning their head away, showing the whites of their eyes (sometimes called “whale eye”), and freezing or becoming suddenly stiff. A growl is not misbehavior. It is the animal’s clearest verbal warning that it needs space. If you see tense muscles and a rigid posture, the dog is telling you it feels cornered.
With wildlife, a defensive animal often makes itself look larger, vocalizes loudly, or charges short distances without making contact (a bluff charge). Bears may huff, snap their jaws, or slap the ground. Predatory behavior looks different: it tends to be silent, direct, and focused. A predatory animal will stalk or approach steadily without the dramatic warning displays of a defensive one.
When Disease Changes the Rules
Rabies scrambles every normal behavioral signal. A rabid animal may lose its natural fear of humans entirely, wandering in the daytime when it’s normally nocturnal. It may appear aggressive, disoriented, or strangely affectionate. Other signs include excessive drooling, difficulty swallowing, staggering, and seizures. Any wild animal behaving in a way that seems “wrong” for its species, especially a raccoon, skunk, fox, or bat that approaches you without fear, should be treated as a rabies risk.
How to Respond During an Attack
Your best response depends entirely on the species and the type of aggression.
For bears, the National Park Service advises against fighting a surprised bear. Back away slowly, avoid direct eye contact (bears read it as a challenge), speak calmly, and wave your arms so the bear recognizes you as human. Pick up small children or pets immediately. If a bear bluff-charges, hold your ground. If it makes contact, your response depends on the species. With a grizzly or brown bear, play dead: lie flat on your stomach, spread your legs to make it harder for the bear to flip you, cover your head and neck with your hands, and keep your backpack on for protection. With a black bear, the opposite applies. Fight back with everything you have. Do not play dead.
There is one critical exception to both: if any bear is acting predatory (stalking you silently, following you persistently, approaching without defensive signals), fight back regardless of species.
For coyotes in urban settings, wildlife agencies recommend a technique called hazing. Make yourself big and loud: maintain eye contact, shout, stomp your feet, throw rocks or sticks in the animal’s direction, and use noisemakers like air horns if you have them. The goal is to reinstill a healthy fear of humans. Keep pets on a leash, especially at dawn and dusk when coyotes are most active.
For snakes, the best response is simply to back away. Most snakebites happen when people try to handle, kill, or get a closer look at a snake. If you’re bitten, stay as calm and still as possible to slow the spread of venom, remove rings or tight clothing near the bite before swelling starts, and get to medical care. Do not apply a tourniquet, cut the wound, or try to suck out venom.
What to Do After a Bite or Attack
For minor bites or claw wounds that only break the skin, wash thoroughly with soap and water, apply antibiotic ointment, and cover with a clean bandage. For deep wounds where the skin is badly torn, crushed, or bleeding heavily, apply firm pressure with a clean cloth or bandage first to control bleeding, then get to an emergency room.
Any bite from a wild mammal warrants medical evaluation for rabies, even if the wound itself seems minor. Rabies is nearly always fatal once symptoms appear, but it is entirely preventable with prompt treatment after exposure. Bites from bats are particularly easy to overlook since the puncture marks can be tiny enough to miss.
Reducing Your Risk
Most animal attacks are preventable. The patterns in the data point to a few consistent rules. Never feed wildlife, even casually. Food-conditioned animals are the ones that eventually bite someone. Store food in sealed containers when camping, and keep trash in closed bins at home if you live near coyotes or bears. Give all wildlife a wide buffer, especially mothers with young. In bear country, make noise while hiking so you don’t surprise anything around a blind corner.
In urban areas, supervise pets outdoors, avoid walking dogs off-leash at dawn and dusk, and don’t leave pet food outside. With unfamiliar dogs, let the dog approach you rather than reaching toward it, and respect the early warning signs. A dog that freezes, stiffens, or turns away is asking for space. Giving it that space is the simplest and most effective bite prevention there is.