Why Eating Like a Bird Might Get You Banned From Holiday Dinners

Some birds have terrible table manners. While many dinner guests are guilty of ignoring etiquette — especially around the holidays — some feathered friends have habits far more egregious than monopolizing the mashed potatoes or grabbing the last dinner roll. 

Predatory birds are particularly problematic diners. Their hooked beaks, powerful jaws and knife-like claws make mealtime a messy affair. And with an appetite for still-squirming entrees and a tendency to barf up bones, these high-flying hunters give new meaning to the phrase “eat like a bird.”

Mouse on a Stick

At just 8-10 inches long and weighing little more than a golf ball (1.8 ounces), the Loggerhead shrike looks like any other unassuming songbird. But beneath their modest exterior beats the heart of an avian assassin. 

Nicknamed “butcherbirds” due to their macabre methods for killing and dismembering their prey, these tiny terrors can take down animals nearly double their size. Though they often feast on large insects, shrikes also hunt lizards, frogs, mice and even other songbirds. 

The honorary raptors of the songbird family, shrikes have hooked beaks like hawks and falcons. But they lack the large skull, strong jaws and robust bones of these larger predatory birds. And while raptors use their powerful feet and sharp talons to attack their prey, the shrikes’ toes are designed more for perching than piercing. 

“What intrigues me about the shrikes is that they come from, what I call, a songbird template,” says Dr. Diego Sustaita, Assistant Professor of Biology at California State University San Marcos. “They haven’t experienced this evolutionary drive that hawks and falcons have to pursue vertebrate prey.”

Sustaita studies ecomorphology — the relationship between the ecological role of an organism and its structural adaptations. Although he often works with raptors, he’s interested in shrikes because their hunting prowess seems at odds with their physical stature. 

According to Sustaita, shrikes compensate for their wimpy physique with unusual and violent hunting behaviors. First, they attack their prey with a series of bites to the neck. The shrike’s tomial teeth — pointy projections on each side of the beak— pierce the spinal cord and immobilize the hapless victim. 

With their prey clenched in their beaks, the truly gruesome maneuvers begin. “When they grab [their prey], they’ll often perform this shaking behavior, this twisting motion of their skull that makes their prey flip flop around,” says Sustaita. “What I think they’re doing is using the prey’s inertia against them to help injure the spinal column quicker.” 

Using video footage of shrikes capturing mice, Sustaita discovered the birds can complete 11 head turns per second, causing the body and head of the mice to twist at different speeds. The frenzied whipping motion generates forces up to 6 g. That’s six times the strength of earth’s gravity and comparable to the whiplash experienced by passengers in a low-speed car crash. Forces that strong are more than enough to snap the neck of a large rat. 

Sustaita suspects the shrike’s tomial teeth enhance traction during head-shaking behavior and keep the prey from slipping out of the bird’s beak. “I think it’s like cleats on shoes for athletes,” he says.

Loggerheads also have a grisly method for stowing their food. Since their feet lack strong muscles to hold down prey while they eat, they use sharp branches, thorns, cactus spines and barbed wire fences to skewer their quarry before pulling off bite-sized chunks. Shrikes often kill more prey than they can eat right away, so they leave the lifeless leftovers hanging —like tiny carcasses strung up in a bird-sized butcher shop. 

Jaws Versus Claws 

Unlike shrikes, real raptors rarely leave leftovers. And while they don’t share the headbanging habits of their smaller brethren, their predatory practices are equally grisly. 

Although hawks and falcons look superficially similar, they’re not closely related. Both birds have relatively large skulls, deep beaks and strong feet, but they have different ways of immobilizing and killing their prey. These hunting methods are reflected in their different body structures.

“The biggest difference comes with how they use their beaks,” says Sustaita. “When a falcon gets a hold of its prey, it will use its beak to bite its neck and break its spine in some way.” 

Falcons, like shrikes, have a tomial tooth on each side of their beaks that helps them puncture flesh and disarticulate the cervical vertebrae. They also have well-developed jaws to help them grasp their prey. “Their jaw muscles are huge,” says Sustaita. “They take up a lot of the mass of their skull, certainly in proportion to their body size.” 

These enormous jaw muscles enable falcons to produce a higher bite force than hawks. But it’s not just the size of the jaws that matters. 

“That bite force that they generate is not just a product of their more highly developed jaw muscles,” says Sustaita. “It’s also a product of how those muscles are oriented around the joint to increase their leverage.” 

Unlike falcons, hawks rely on their feet to immobilize their prey, often squeezing their victims so tightly they suffocate. Two extra-large talons on their first and second toes improve their grasp. 

Not surprisingly, the muscles controlling hawks’ toes and talons are unusually large and strong. “They take up a large proportion of their body mass,” says Sustaita.  “And as you’d expect, hawks tend to generate higher grip forces, relative to their body sizes, than do falcons.”

Hawks only use their beaks when they begin to feed. They typically start by plucking fur or feathers from their ensnared victims. What’s even more morbid, according to Sustaita, is hawks often start gorging while their prey is still alive. 

Barfing up Bones

Owls are a lot like hawks — they rely on their strong feet to subdue prey and use their beaks mainly for feeding. But these stealthy predators have some unusual and rather foul habits that set them apart from their raptor relatives.

For starters, owls often swallow smaller prey whole, usually headfirst. If the prey is too big to consume in a single gulp, they bite off extra-large chunks. The unique articulation of their lower jaws allows owls to open their mouths unusually wide. By hurling their head to and fro, they force the prey through their spread jaws and down their gullets.

Because owls aren’t very particular about what they devour, their digestive system must contend with bones, fur and feathers. Like all birds, their stomachs have two parts. The first part, called the proventriculus, produces enzymes and acids that begin the process of digestion. Here, the digestible parts of an owl’s meal are liquefied before being passed to the second part of the stomach, called the ventriculus or gizzard.

The gizzard works like a filter, sorting the digestible flesh from the indigestible bits of fur, bones, feathers and teeth. The digested soft tissue passes on to the small intestine, while the undigested parts get compressed into an oval shaped mass called a pellet. 

The pellet travels back to the proventriculus where it remains until it’s regurgitated by spasms of the owl’s esophagus. Pellets can be stored in the proventriculus for up to 20 hours, but they block the entrance to the digestive system and must be ejected before the owl can consume its next meal. 

Although many other meat-eating birds produce pellets, owl pellets are often larger and frequently contain intact bones or even whole skeletons. Sustaita once found the complete skull of a barn owl in a pellet coughed up by a great horned owl. 

Another cool feature of owls, according to Sustaita, is their ability to rotate their toes. They’re what’s called facultatively zygodactyl. This means they can swivel their fourth toe backwards, so they have two toes facing forward and two facing back. “Some researchers think that this ability to create the zygodactyl grip somehow enhances their grip force capabilities,” says Sustaita. 

Owls generally have higher grip forces than hawks, an adaptation scientists attribute to their nocturnal lifestyle and the difficulties of hunting in the dark. “They really need to maximize their efficacy with their talons,” says Sustaita. “One way to do that is just make sure that you’ve got plenty of force to get the job done, because there’s not much room for error there.” 

Rippers, Gulpers and Scrappers

In contrast to owls and hawks, vultures don’t need their feet to capture prey. After all, the food they’re pursuing is already dead. Vulture feet are superficially similar to hawks, but they are significantly weaker. “Because they’re so highly specialized to scavenging, they don’t need to worry about their foot morphology,” says Sustaita.

Vultures are divided into two evolutionary lineages — the New World vultures found in the Americas and the Old World vultures that inhabit Africa, Asia and Europe. Although their slightly different ancestries influence their foot structure, their feet are mainly designed for scampering around on the ground, fighting for positions at the carcass or perching on their roosts.

What’s more interesting than their foot morphology, says Sustaita, is that different species of vultures specialize on different parts of the carcass. Old and New World vultures are divided into three groups based on their feeding specialties: the scrappers, the rippers and the gulpers. 

Sustaita’s former thesis advisor, and fellow ecomorphologist, Dr. Fritz Hertel, found that different beak and skull morphologies are associated with each specialty. 

Rippers are the first birds to get down to the carcass and tear it open with their beaks. These birds, which include the king vulture and lappet-faced vulture, have the strongest beaks and widest skulls. They feed primarily on the tough skin, hide, tendons and muscles. 

The gulpers are next in line. They dive in and swallow up big chunks of organs. The California condor and the African white-backed vulture are both gulpers. These birds have moderate beak strength and the narrowest skulls. 

The gulpers are followed by the scrappers — they take whatever’s left after the other two groups have done their business. Scrappers, like the black vulture and the Egyptian vulture, have the weakest beaks and somewhat narrow skulls. As their name suggests, they primarily feed on the smaller scraps on and around the carcass. 

Scrappers often keep their distance while the other vultures are feeding, waiting patiently to snag a morsel. “If you’re just a wimp and you just have this little tweezer beak, you can pick up scraps,” says Hertel, a biology professor at California State University, Northridge. “But you’re going to get your ass kicked by everything else.”

Hertel says vultures fill an interesting niche, and he believes their opportunistic diets will help them survive even as other animals go extinct. “As long as there’s death, the vultures will be around to clean it up.” 

Spoiled Appetites

While gulping down guts or tearing into wriggling rabbits seems gross to humans, these evolutionary adaptations are critical to birds’ survival. Despite their lack of hands or teeth, these aerial predators have developed remarkable methods for catching and devouring their prey. With their built-in forks and knives — and their total disregard for table manners — they could make quick work of a holiday feast. 

So, the next time a guest chews with their mouth open or picks their teeth at the table, just be thankful no one invited a Loggerhead shrike or a great horned owl to the dinner party.

If you want to learn more about bird behavior, check out this article about pecking orders.