Instincts are great, except for those unfortunate times when they make an animal go completely haywire, sometimes with disastrous results. Here are eight bizarre glitches that cause animals to do some very strange things — some of them even fatal.

1. The Ant Vortex of Death

The ant spiral of death is the perfect example of what can happen when instincts go wrong. Blind army ants, particularly soldier ants, depend on pheromone trails left behind by the leading ant. As the ants move, they reinforce the trails. But if one ant wanders off an established path, it will loop around and around, leading the ants behind it — all of them reinforcing the trail as they follow. This sometimes leads to large swirling vortexes.


The ants will keep up this routine until they die of exhaustion or starvation — or until the vortex is interrupted.


2. Sphexish Digger Wasps On Constant Repeat

Digger wasps are renowned for being automatons — insects with hyper-specialized genetic routines that result in extremely predictable and stereotypical behaviors, like nest building and resource provisioning. Sometimes, these programmed behaviors get the better of them, particularly when there are mischievous naturalists around.

Digger wasps, sometimes referred to as sphex wasps, have famously been observed arriving home with a paralyzed insect, which they drop near the opening of their nest. Prior to entering the nest with the captured insect, the wasp goes inside to conduct an inspection, leaving its meal outside. But during the inspection, an experimenter can move the prey a few inches away from the opening. When the wasp emerges, it’s ready to bring the insect indoors — but its meal has been moved. After relocating the bug and dragging it back to the opening, the wasp will once again go through the inspection routine, leaving the insect outside. And once again, if the experimenter should move the insect, the sphex would once again relocate it and conduct another inspection. And over and over and over again.

This is actually where the word “sphexish” comes from. Years ago, both Douglas Hofstadter and Daniel Dennett used this scripted behavior as an example of how apparent thoughtful behavior can actually be quite mindless — the opposite of free will.

3. Incorrect Avian Imprinting

Also called filial imprinting, it’s the sometimes quirky process through which early social preference (or “imprinting”) among young birds becomes restricted to a specific object or category of objects. Imprinting happens during a brief but sensitive time (often on the first day of life!). Normally, a chick imprints to its mother, resulting in attachment. But sometimes this process can go awry and the chick imprints to something other than a member of its own species.

Impossibly cute video of a gosling that has imprinted to a puppy:

This poor Jack Russell now has a companion for life:

The biologist Konrad Lorenz once had a goose imprint on his gum boots; afterwards, the goose would follow anyone who wore the boots. Naturalist Joe Hutto became a “mother” to a flock of wild turkeys. This can be catastrophic to certain birds, particularly when mating is concerned; famously, George Archibald had to perform a mating dance with his imprinted female whooping crane to get it ready for artificial insemination.

4. Sheep Over a Cliff

Somewhat similar to the ant vortex, sheep will blindly follow the members ahead of them. This can lead to disastrous consequences — like that time a herd threw itself off a 50 foot (15 meters) cliff killing 400 individuals. Some 1,100 sheep survived, cushioned by the sheep lying dead at the bottom.

5. Beached Whales and Dolphins

Mass beachings of cetaceans is a bit of a mystery to scientists. These beachings can include one individual, or even dozens at a time.

One possibility is that large whale species, like those found near Madagascar, often become beached together owing to their matriarchal nature. When the leader becomes ill and heads towards shore, the others are likely to follow. Another possibility is that human sonar is screwing whales and dolphins up. Other theories suggest these animals were chasing a shoal of fish and then couldn’t get back into deeper water, they were being chased by predators or rivals, or they followed a member of the pod who got into trouble. Like the time a stray baby dolphin pulled 150 members of its pod into shallow waters in Australia. (Credit: Mirror)

6. Same-sex Behavior in Insects

Bugs sometimes engage in what appears to be homosexual behavior. For other clades, like mammals and birds, this isn’t a problem; same-sex behaviors in these species are often understood as “practice” for young adults and as a way to maintain group alliances. But for insects, this isn’t the case. Indeed, these botched mating efforts are extremely dangerous and energy-consuming. There’s simply no purpose for it. The reason for it, say scientists, is that insects simply haven’t evolved the capacity to be more discriminating in their mating choices. This has led to “mating confusion” in which some bugs try to mate with members of other species — and even inanimate objects like beer bottles. Biologists theorize that same-sex behavior is “worth it” for males because “the cost of rejecting a valid opportunity to mate with a female is greater than than of mistakenly mating with a male.”

7. Moths to a Flame

Surprisingly, there’s no good theory to explain why moths are hopelessly attracted to lights. It’s widely held, for example, that moths fly towards unnatural light because it throws off their internal navigation systems. Moths didn’t evolve around bright lights, goes the theory, instead adapting to the distant sun, moon, and stars. Using transverse orientation, moths and other insects can fly at a constant angle relative to a distance light source, like the moon. But that theory doesn’t hold up when you consider that fires have been around for a very long time, and that moths may not even use transverse orientation. Another theory is that the infrared light spectrum emitted by a flame contains some of the same frequences of light given off by female moths’ pheromones. So males head to the light in hopes of sex, but are instead met with a fiery death. But this theory is not good either as moths are more attracted to ultraviolet light. [source: LiveScience]

8. A Deer Caught in the Headlights

Deer are notorious for becoming transfixed by car headlights. Instead of running away, they freeze in place to their own peril. Why is this? C. Laiborne Ray offers an explanation:

“Deer are crepuscular,” said David C. Yancy, a deer biologist with the Kentucky Department of Fish and Wildlife Resources. Their activity peaks within an hour or so on either side of sunrise and sunset, so their vision is optimized for very low light. When a headlight beam strikes eyes that are fully dilated to capture as much light as possible, deer cannot see at all, and they freeze until the eyes can adjust. “They don’t know what to do, so they do nothing,” Mr. Yancy suggested.

So it isn’t as much an animal “glitch” as it is a consequence of human actions. They simply haven’t had enough time to adapt.

Top image: Mary_L/Shutterstock.