Do Lemmings Really Jump Off Cliffs?

Lemmings are small, fierce rodents that make their home in Arctic environments -- and (spoiler alert) the idea that they kill themselves by following each other off cliffs is a myth. Learn what Disney had to do with it (and what lemmings are really like) in today's episode of BrainStuff, based on this article: https://animals.howstuffworks.com/mammals/lemmings.htm

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Episode Transcript

Speaker 1 (00:01):
Welcome to BrainStuff, a production of iHeartRadio. Hey BrainStuff, Lauren
Vogelbaum here. You might have heard the term lemming in
context of a metaphor for someone so foolish that they
would follow a group into a bad situation rather than
apply critical thinking and act accordingly. As in, what are you,

(00:23):
a lemming? If everyone else jumped off a cliff, would
you do that too? there's an idea that lemmings are
creatures prone to mindlessly jumping off cliffs en masse. However,
the root of this metaphor is not impressionable people. Lemmings
are actually several species of small rodents native to the
Arctic regions of the globe. Most closely related to voles

(00:46):
and muskrats, lemmings are stocky little creatures with short tails, ears,
and snouts, making them look sort of aerodynamic, if a
tribble could look aerodynamic. They measure around just 5 to
7 inches in length, that's 13 to 18 centimeters. They
burrow under the snow in winter, eat tough plants that
grind down their continuously growing teeth, and provide a food

(01:08):
source for predators like arctic foxes and snowy owls. Lemmings
migrate when food becomes scarce and can even swim across
rivers and lakes when necessary. They also have a reputation
for being extremely aggressive. Rather than running away from a predator,
they'll often charge their attacker. They've even been known to

(01:29):
attack humans who are studying lemmings and are working sled dogs.
If you look up photos of lemmings, you'll inevitably find
images where the lemming in question is baring its long
front teeth and apparently screaming at the camera. Or squeaking, anyway.
All of which is impressive for something that resembles a
slightly shrimpy guinea pig. So why would these little creatures,

(01:53):
interested in preserving life and limb to the point that
they would fight a human or a weasel rather than
be eaten, also jump off of cliffs? The truth is,
this reputation is a myth. For the article this episode
is based on, HowStuffWorks spoke via email with Rolf Anka Eames,
a researcher in the Department of Arctic and Marine Biology

(02:14):
at the Arctic University of Norway. He said, This idea
stems from the migrations observed in one lemming species, the
Norwegian lemming. During the peak years of this species, a
large number of individuals migrate out of their normal habitat
and die in large numbers. It's unclear what causes these migrations,
but social stress, food shortage, or predators are candidates. Suicide

(02:38):
is not a good explanation. The lemming suicide myth was
popularized in a 1958 documentary segment from Disney with documentary
and heavy scare quotes called White Wilderness, which claimed that
this happens once every decade or so in response to overpopulation.
Footage in the segment shows a few dozen lemmings running

(03:00):
across the snow and falling from a cliff into water
to their apparent deaths, accompanied by narration saying, a kind
of compulsion seizes each tiny rodent, and, carried along by
an unreasoning hysteria, each falls into step for a march
that will take them to a strange destiny. That destiny
is to jump into the ocean. But future investigations have

(03:25):
shown that these scenes were faked. The lemmings they filmed
aren't even native to the area of Alberta where the
footage was shot. Allegedly, the segment's producers imported a group
of the rodents and then used tight angles, misleading editing,
and a good shove to get their dramatic footage of
quote-unquote lemming suicide. Which, if true, is horrible. But it

(03:48):
convinced so many people that 60 years later, zoologists still
get asked whether it's true. But it's just a myth
with a weird tiny kernel of truth. Lemmings do go
through population cycles with highs and lows every few years.
Some species, like the Norwegian lemming, are known to disperse

(04:08):
or migrate in large numbers when booms in populations lead
to food or personal space becoming scarce. This mass dispersal
can sometimes lead to confused buildups on the banks of
a body of water. Lemmings are good swimmers for short stints,
but if their coat gets soaked through, they can accidentally
drown or get too cold to recover. So deaths can happen,

(04:33):
even lots of them at a time, but it's not
purposeful or even particularly hysterical behavior, just an attempt to
alleviate immediate stress. There's also a tall tale that lemmings
can literally explode from anger, which, of course, they can't,
though they are well known to leap and shriek at

(04:54):
intruders to their habitats. A lemming's supposed mindless behavior and
propensity for explosion are were both factors in a series
of video games called Lemmings, the first of which debuted
in 1991 for the Amiga PC, developed by the studio
DMA Design, which has since become Rockstar North. In these,
albeit non-realistic, puzzle games, the player guides groups of anthropomorphized Lemmings,

(05:19):
each sporting green hair and a blue robe, to safety
through various environments and obstacles. The Lemmings did often fall
off of cliffs, and if you ran out of time
on a given level, any that hadn't reached the end
would explode. We should say here that people have been
observing lemmings' behavior and population cycles with a sort of

(05:39):
amused bewilderment for centuries. Going back to the 1500s, there
are descriptions out of Scandinavia of lemmings pouring down from
the sky during rainstorms. This is probably based on the
reality that in the summer, when the weather turns and
the snows melt, lemmings' winter burrows disintegrate around them, leaving
a perhaps surprising number of the rodents exposed for the

(06:02):
first time in several months. We'll get into what lemmings
are really like in a minute, but first we're going
to get into a quick word from our sponsor. In reality, lemmings,
all 20 or so species, are just slightly unusual rodents.

(06:26):
Depending on the species, they may burrow underground in the
summer if the ground is warm enough to not be frozen.
They typically make burrows in the snow during the winter,
constructing nests underneath the blanket on the ground surface from
whatever grasses, mosses, feathers, and fur they can find. Snow
is actually a great insulator. Heat from the earth below

(06:47):
trapped by snow can keep the ground just above freezing,
creating a sort of shallow pocket along the ground called
a subnivian zone. So, these rodents can access food and
keep cozy in the cold, and visually hidden from predators
looking for a snack. Sharp-eared predators can still hear them
under the snow and pounce to break through, though. During

(07:11):
the lemming's breeding season, which can be in the summer,
the winter, or both, a female lemming might have multiple
litters of multiple young, up to 13 per litter, which
helps them proliferate during boom years. Different species of lemmings
have coats of different colors to help them blend into
their environments, from whites to grays and creams to browns,

(07:33):
often with a lighter belly and a darker back. Some
have coats that will lighten or even completely whiten during
the winter to match the snow. But the Norway lemming
has a famously immodest coat, incorporating mottled golds, reds, black
and white, like a calico cat. It does help them
blend in with local rocks and grasses during the summer,

(07:54):
but it doesn't lighten over the winter. However, if they
build out their snowy burrows successfully, they might just not
need camouflage because they don't often surface during that time.
Most lemmings are herbivores, eating grasses, sedges, mosses, and lichens,
but some species will branch out to consuming snails, slugs,

(08:15):
and other invertebrates. They live only a couple of years
in the wild, but they're keystone species in their environments.
Eames said, Lemmings are very important to the functioning of
Arctic ecosystems. Their cycles are necessary for the maintenance of
Arctic biodiversity through their role as prey and grazers of plants.

(08:37):
In an ecosystem, populations of specific species may fluctuate drastically
over a predictable period of time. Population cycles happen in
ecosystems all over the world, and rodents are a common
group of animals to experience population cycles. These cycles can
be driven by disease, food availability, and predation. Lemming populations

(08:58):
spike every few years, sometimes up to a thousandfold. This
happens about every three to five years, though not like
clockwork as with some other population cycling species. However, when
they do, all of the predators on the tundra that
depend on lemmings for food, like arctic foxes, hawks, and
coastal birds called long-tailed jaegers, will eat very well that year.

(09:23):
They're thus more fit to reproduce. Some animals, like the Jaegers,
will actually choose whether to breed or not in any
given year based on lemming availability. The rodents make excellent
food for their young. High lemming populations also create lots
of droppings, which feed the growth of vegetation. And they
can also affect the reproduction of other prey species. For example,

(09:45):
if Arctic foxes fill up on lemmings, they might not
steal quite so many snow goose eggs that year. leading
to a flux in the goose population the next year. Though,
of course, since there will also be more foxes the
next year, the cycle continues. Population spikes in lemmings can
also be pretty destructive. During the summer months, lemmings eat

(10:06):
lots of living vegetation. And when lemming populations are at
their peak, the rodents eat so much that they have
to travel across the tundra in great numbers in search
of greener pastures. These migrations are unusual, too. During these years,
lemmings eat so much that the results are noticeable from space,
and the plants can take years to recover. Although it

(10:30):
might seem detrimental to the ecosystem to have the vegetation
of the tundra so destroyed at regular intervals, research has
found that when you exclude lemmings from the system, the
plant life actually suffers over time. There's been a lot
of research into these population cycles, what causes them, and
what effects they have over the long and short term.

(10:51):
I understand that it's something of a heated topic among ecologists.
Eames said, The main hypotheses about the population cycles in
lemmings postulate that they result from interaction between predators, foxes, weasels,
and raptors, and the lemmings themselves, or between plants and
the lemmings that eat them. Predator-prey cycles have presently the

(11:11):
most support. The irregularity in the dynamics is likely to
be due to disruption from climate variability and change. Lemmings
have been identified as a group particularly vulnerable to shifting climates.
Because lemmings depend on cold winters in their tundra habitats,
climate change is creating major problems for these important Arctic residents.

(11:35):
As we said earlier, lemmings often build burrows in the deep,
soft snow in the winter, nesting and finding food along
the ground underneath in the subnivian zone. When winter temperatures
are just a bit warmer, harder packs of snow and
ice can block lemmings from their food source and make
it more difficult for them to dig out their shelters. Again,

(11:56):
fluctuations of lemming populations are natural wherever these critters live,
but researchers have been seeing more sporadic cycles, or longer
periods between lemming peaks over the past 30 years or so.
There's concern that climate change could be to blame, or
that the warming climate could even lead to a collapse
of the population cycle altogether, with new, permanently low lemming

(12:19):
populations in some areas. With lemmings as a key intermediary
between plant life and predator species, this could lead to
changes in entire ecosystems, including the extinction of mammals and
birds that depend on lemmings as a food source. Researchers
are still looking into it. For all the myths around

(12:40):
these tiny, cute, fierce critters, the reality is teaching us
a lot about how ecosystems work. Today's episode is based
on the article, Lemmings Jumping Off Cliffs in Mass is
a Myth, on HowStuffWorks.com, written by Jessalyn Shields. BrainStuff is
a production of iHeart Podcasts in partnership with HowStuffWorks.com and

(13:03):
is produced by Tyler Klang. Of four more shows from
iHeart Podcasts, visit the iHeart Radio app, Apple Podcasts, or
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