12:54 AM
[ INTRO ] If I asked you to picture a forest, you might
envision a sunny grove with some deer gently nibbling on leaves as they mosey on through. But those deer could actually be searching
for a baby bird or two to munch on. Yes, deer can be carnivorous. In fact, many supposed plant-eaters sneak
the occasional fleshy snack, usually because some nutrients are just easier to get from
animal parts.
So here are six so-called vegetarians that
regularly eat meat and bonesincluding ours. [1. Deer] Everyone knows that Bambi and his friends
are vegetarians. I mean, deer are quite literally built to
eat plants.
As ruminants, they have the ability to ferment
plant material in their specialized stomachs, which allows them to live off a diet that
would be way too fibrous for most creatures. But lots of deer apparently missed that memo,
as theyve been caught eating everything from baby birds to human bones. Yes, I said human bones. A 2017 paper suggested that deer might frequently
gnaw on bodies left exposed in their habitats.
We dont have any evidence that deer kill
people, outside of accidental encounters with vehicles. But they do most definitely kill birds. Like, a lot. Nest cameras in North Dakota have filmed white-tailed
deer snacking on chicks more often than traditional predators.
And on an island in Scotland, red deer have
been seen biting off the heads of seabird chicks and chewing on birds legs. Scientists think these deer are specifically
targeting bones, since theyre rich in phosphorus, calcium, and other minerals that are less
common in plants. They need those nutrients to build strong
bones for themselves, as well as those impressive antlers that deer are so known for. Sure, a rich mineral lick would suffice, but
those arent always around whereas baby birds are everywhere.
Youd expect that other ruminants would
have similar dietary needs, and therefore might also snack on the occasional bone. And yeah. They do. Sheep, cows, and even giraffes have been seen
sucking on bones or actively killing small animalsusually baby birds.
Apparently theyre just a super convenient
source of minerals, if you dont happen to have a salt lick at hoof. [2. Squirrels] Rodents are another group of animals that
are well known for their vegetarian dietsespecially ones like squirrels and chipmunks. They just scamper along branches and stuff
their furry little cheeks full of yummy acorns, right? Well, it turns out when theyre not busy
stashing nuts and eating the cherries off my cherry tree, squirrels and chipmunks take
full advantage of their climbing ability to go after bird eggs and nestlings.
They also seem to have no qualms eating frogs,
lizards, snakes, and even turtles. And theyll kill and eat all sorts of small
mammals, including other species of squirrel or each other. Maybe that shouldnt be so surprising, since
rodents are notorious for eating their own young. But when they do, its usually considered
a sign something is going wrong.
Squirrels will act as predators when completely
healthy, so there must be some other reason. Like with deer, one important clue is that
they seem to target bones. Forensic scientists note that squirrels frequently
gnaw on skeletons, for exampleand their tiny teeth can cause enough damage to obscure
important clues about the cause of death. So, they might be looking for those extra
minerals like deer are.
Or they could just be looking to grind down
their teeth. All rodents have continuously-growing incisorsyou
know, those rodent-y things in frontso chomping on hard bones might keep them in
check. But in many cases, like with the baby birds,
squirrels definitely seem target flesh, which might mean they hunt for the most obvious
reason: Food. Just extra calories.
Lab experiments have shown that hungrier rodents
are more likely to attack live prey. And other rodents like mice, beavers, and
bunnies will also make a habit of dining on meat if the option is available. Meat consumption is so widespread in rodents
that some scientists argue that they really should be thought of as omnivores, not herbivores. And given that about 40% of all mammals on
the planet are rodents, that go-with-the-flow approach to their diet might have helped them
conquer the world.
[3. Butterflies] Anyone who has tried to grow their own veggies
is all too familiar with the leaf-destroying abilities of most caterpillars. But some moth and butterfly larvae have decided
plants are overrated, opting instead to snack on tasty flesh. Like inchworms in Hawaii with claw-tipped
arms, which will eagerly feast on flies.
Or silk-weaving caterpillars that tie down
snails so they can slurp them from their shells. And all the caterpillars in the subfamily
Miletinae eat aphids. But eating snails and insects pales in comparison
to the moths and butterflies that dine on carrion. Thats right.
There are scavenging butterflies. A lot of them, actually especially when
theyre caterpillars. Most of these caterpillars normally eat plants,
but when the tastiest leaves are taken, theyll go for decaying flesh. As the saying goes, this is life, and no one
gets out alive, so being able to eat dead things is a pretty good way to make a living.
Im not sure that was a saying, but it is
now. Caterpillars tough jawsstrong enough
to tear through starchy leaveshave no trouble with decaying meat. Some species are so common on corpses that
theyre used in forensics. Even adult butterflies get in on the scavenging
action at times, to get nutrients not found in nectar.
They may flock to dead fish for the saltsthe
same reason they hang out on mineral licks or sip turtle tears, which yes, is a thing. But some scientists think they suck down rotting
flesh for the amino acidsthe molecular building blocks of proteins. The species caught using bait made of decaying
meat are known to be super mobile butterflies, and all that extra protein probably helps
them build and keep their flying muscles. [4.
Duikers] Duikers are teeny little antelopes native
to Africa. They are really cute. There are almost two dozen different species,
each more adorable than the last. But dont let their size or their cute features
fool youduikers can be ruthless.
Though theyre generally considered frugivores,
or fruit eaters, animal matter is frequently found in their stomachs by people who cut
open their stomachs, apparently. Things like insects and carrion usually make
up about a tenth of a percent of their diet, which doesnt seem like very much. But studies have found some stomachs with
10% or more of their contents animal-sourced. And they dont necessarily wait for
their meals to die.
In Angola, the yellow-backed duikers taste
for flesh is infamous. According to locals, theyve actually learned
how to eat tortoises, leaving behind empty shells wherever they go. And there are tons of scientific reports of
duikers and their relatives eating all sorts of small birds, mammals, reptiles, and amphibians. More surprisingly, they seem to enjoy killing.
Captive duikers appear to play with living
food, like a cat toying with a mouse. One bay duiker in the Zurich zoo earned a
reputation for stalking, killing, and eating pigeons that landed in its enclosure. But those behaviors might not be natural in
the wild. In fact, why duikers eat meat isnt entirely
clear.
It may be that, like their distant ruminant
relatives, they use meaty snacks as nutritional supplements. Studies of their wild diets suggest that the
plants and fruits they eat are relatively low in minerals and protein, even though the
animals fare better on a high protein diet. But some zookeepers have found they actually
do better when raw meat is excluded from their meals. We just dont know enough about these shy,
adorable, savage little antelopes to say for sure.
[5. Hippos] Hippos might look like gentle giants. But even though theyre considered herbivores,
theyre one of the most dangerous beasts in Africa. Their aggressive nature is legendary its
said they kill more people every year than lions and leopards combined.
And thats probably not just because theyre
territorial. Recently, biologists have come to the conclusion
that they actually have a taste for meat. Hippos will scavenge carcasses they come across,
and theyve been known to walk right up to a feeding crocodile and take a bite of
its kill. But much more direct and savage stories have
emerged over the years, including instances where hippos have definitely killed and eaten
antelopes.
And thats weird, because its been thought
for a long time that hippos simply dont have the stomachsor, more accurately, the
stomach bacteriato digest meat. But a 2015 review argues that the only thing
limiting meat-eating in hippos or most herbivores, really is their ability to
catch and eat it. And that makes sense, considering all the
other supposed herbivores that eat meat when they have the opportunity. But hippos have a few meat-eating advantages
over other herbivores, like their big giant mouths and teeth that can more easily tear
apart hunks of flesh.
And with their bulkand surprising speed
and agilitythey are more than capable of taking down large prey. Just how often hippos eat meat is uncertain,
thoughmost diet studies get their info from plant material found in feces, which
does not tell you whether or not the animal has consumed meat. And its hard to observe everything that
goes into the hippos mouths because they tend to eat at night. Also ...
Its kind of tough to stay close
enough to a giant aggressive hippo to see what its nibbling on. You cant really do a diet study if you
become a part of the diet study. If you know what I mean... [6.
Primates] Obviously, we humans arent always vegetarians. And its no secret that chimpanzees wage
wars against one another, and will hunt, kill, and consume other animals, especially monkeys. But most primates have a more peaceful reputation. Take bonobos, for example.
These chimp cousins were supposed to basically
embody the 1960s hippie movementyou know, making love, not war. Even though theyre basically the same size
and strength as chimpanzees, people thought they opted for a much more vegetarian diet. That is, until about a decade ago, when anthropologists
watched them hunt down monkeys and other, smaller mammals. And those observations are backed by DNAfecal
DNA, to be precise.
A 2010 study of 128 bonobo poop samples found
evidence for recent meat consumption in 16% of them. One reason that these and other primates might
eat the occasional steak is that its hard to get enough Vitamin B12 with a purely vegetarian
diet. B12 is essential for healthy blood and nerve
cells, and we mammals cant make it ourselves. Some animals, like ruminants and other animals
with multiple stomachs, like hippos, have bacteria in their guts that produce this key
nutrient.
So they get what they need because their weird
anatomy. We have some of these bacteria, too, but theres
a catchthey live so far along in our digestive tract that we just poop out all the B12 that
they make. Thats probably why bunnies and some rodents
eat their own feces, and if they dont, they get B12 by having a non-vegan diet usually,
by supplementing with insects. So it makes sense that even the most vegetarian-leaning
primates might actually be somewhat omnivorous to ensure they get enough B12.
Many primates probably eat insects for this
exact reason, but somelike bonobos and chimpanzeesclearly have no problem subbing
in a little red meat instead. And I do feel like mentioning you can get
B12 without meat, its just us humans have a lot more dietary opportunities than wild
chimpanzees. But in the end, even animals we thought were
super strict vegans might cheat a little more oftenor a lot more oftenthan we ever
imagined. But if they do eat a little flesh now and
then, they probably have a good reason for it.
Learning what animals eat and why can help
us take better care of them in captivity and understand our own dietary needs. If we want to go full vegan, we can just get
a B12 from pills or shots, or fordfied food, not from eating our own poop. Thanks for watching this episode of SciShow,
which could not exist without the support of our Patreon patrons like Matthew Brant,
our President of Space. Thank you Matthew for your continued support
of SciShow.
[ OUTRO ].
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