The animals that detect disasters
For millennia, people across the globe have reported
alarmed animal behaviour in the run-up to natural
disasters. Could these signals be used to warn us of
impending catastrophes?
In 2004, a tsunami triggered by a 9.1 magnitude
undersea quake off Indonesia decimated coastal
communities around the Indian Ocean, killing at least
225,000 people across a dozen countries. The huge death
toll was in part caused by the fact that many
communities received no warning.
Local manmade early warning systems, such as tidal and
earthquake sensors, failed to raise any clear alert.
Many sensors were out of action due to maintenance
issues, while many coastal areas lacked any tsunami
siren warning systems. Haphazard communication also
failed to provide warnings, with many text messages
failing to reach mobiles in threatened areas or going
unread.
Yet in the minutes and hours before surging walls of
water up to 9m (30ft) high smashed through coastlines,
some animals seemed to sense impending peril and make
efforts to flee. According to eyewitness accounts,
elephants ran for higher ground, flamingos abandoned
low-lying nesting areas, and dogs refused to go
outdoors. In the coastal village of Bang Koey in
Thailand, locals reported a herd of buffalo by the
beach suddenly pricking their ears, gazing out to sea,
then stampeding to the top of a nearby hill a few
minutes before the tsunami struck.
"Survivors also reported seeing animals, such as cows,
goats, cats and birds, deliberately moving inland
shortly after the earthquake and before the tsunami
came," says Irina Rafliana, previously part of an
advisory group for the United Nations International
Strategy for Disaster Risk (UNISDR) and now a
researcher at the German Development Institute in Bonn.
"Many of those who survived ran along with these
animals or immediately after."
Rafliana recounts similar stories tied to her field
work around other disasters, such as the 2010 tsunami
generated by a subsea quake near Sumatra, which killed
nearly 500 people on the Mentawai Islands. Here too,
however, some animals, such as elephants, were reported
to have responded as if possessing some kind of early
knowledge of the event. Just days ago, a newly re-
released turtle made a sudden U-turn two days before
January's volcanic eruption in Tonga.
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Early warning systems do not exist in many areas struck
regularly by natural disasters. In 2017, the World
Meterological Organisation found that the governments
of around 100 countries still lack early warning
systems for natural disasters to which they were prone.
But these accounts about animal behaviour before
disasters have prompted some researchers to devote
serious scientific attention to the theory that animals
may have inbuilt systems which alert them to impending
natural disasters. It raises an intriguing question
could animals provide natural early warning systems for
humans?
Survivors also reported seeing animals, such as cows,
goats, cats and birds, deliberately moving inland
shortly after the earthquake and before the tsunami
came Irina Rafliana
The earliest recorded reference to unusual animal
behaviour prior to a natural disaster dates back to 373
BC, when the Greek historian Thucydides reported rats,
dogs, snakes and weasels deserting the city of Helice
in the days before a catastrophic earthquake. Other
reports dot history. Minutes before the Naples quake of
1805, oxen, sheep, dogs and geese supposedly started
making alarm calls in unison, while horses were said to
have run off in panic just prior to the San Francisco
earthquake of 1906.
Even with advanced technology it can be difficult to
detect many kinds of impending natural disasters. In
the case of earthquakes, for example, seismic sensors
lurch into jolted squiggles only as the earth-juddering
shocks are actually happening. Making reliable
predictions requires precursor signals and, as yet,
scientists haven't found any signals that seem to occur
consistently before big quakes. Hence the growing
willingness of some scientists to consider more
unorthodox warning signals such as animal behaviour.
"Even with all the technology available today, we are
not able to properly predict earthquakes or most
natural catastrophes," says Charlotte Francesiaz,
leader of an ornithological team at the French
Biodiversity Office (OFB), and part of the Kivi Kuaka
project, which is examining how migratory birds
crossing the Pacific seem able to dodge storms and
other hazards.
One of the most important investigations into how
animals could predict disasters was carried out five
years ago by a team led by Martin Wikelski from the Max
Planck Institute of Animal Behavior in Germany. The
study involved recording the movement patterns of
different animals (cows, sheep and dogs) a process
known as biologging on a farm in the earthquake-prone
region of the Marches in central Italy. Collars with
chips were attached to each animal, which sent movement
data to a central computer every few minutes between
October 2016 and April 2017.
During this period, official statistics recorded over
18,000 quakes in the region, from tiny tremors
measuring just 0.4 magnitude up to a dozen quakes
notching 4 or above including the devastating
magnitude 6.6 magnitude Norcia earthquake.
The researchers found evidence that the farm animals
began to change their behaviour up to 20 hours before
an earthquake. Whenever the monitored farm animals were
collectively 50% more active for more than 45 minutes
at a stretch, the researchers predicted an earthquake
with a magnitude above 4.0. Seven out of eight strong
earthquakes were correctly predicted in this way.
"The closer the animals were to the epicentre of the
impending shock, the earlier they changed their
behaviour," Wikelski said in 2020 when the study was
released. "This is exactly what you would expect when
physical changes occur more frequently at the epicentre
of the impending earthquake and become weaker with
increasing distance."
Another study carried out by Wikelski monitoring the
movements of tagged goats on the volcanic slopes of
Mount Etna in Sicily also found the animals seemed to
have an advance sense of when Etna was going to burst
into life.
Over in South America, behavioural ecologist Rachel
Grant now at London South Bank University has found
similar results. She carried out biologging of animal
movement patterns using motion-triggered cameras inside
Yanachaga National Park in the Peruvian Andes over a
period which included the magnitude 7.0 Contamana
earthquake in 2011.
"The number of animals recorded on the camera traps
started to decrease about 23 days before the earthquake
with the decrease accelerating eight days prior to
the earthquake," Grant said in her 2015 paper on the
research. "On days 10, six, five, three and two prior
to the earthquake and on the day of the earthquake
no animal movements were recorded, which is highly
unusual."
Crucially, Grant also found evidence of what might be
triggering the changes in local animal behaviour, in
the shape of a series of strong perturbations in local
atmospheric electric charges every two to four minutes,
starting two weeks before the earthquake. A
particularly large fluctuation was recorded around
eight days before the Contamana earthquake coinciding
with the start of the second stage of the animals
disappearing from view.
Even with all the technology available today, we are
not able to properly predict earthquakes or most
natural catastrophes Charlotte Francesiaz
Scientists are now exploring whether these
electromagnetic perturbations in the atmosphere prior
to earthquakes could be a warning sign of impending
quakes which animals may be sensing.
Earthquakes are invariably preceded by a period when
severe stresses arise in deep rock stresses known to
create electronic charges called "positive holes".
These highly mobile electronic charge carriers can flow
quickly from the crust to the Earth's surface, where
they ionise air molecules above where they appear. Such
ionisation has been noted prior to quakes across the
globe. As these positive holes flow, they also generate
ultra-low frequency electromagnetic waves, providing an
additional signal that some animals may be able to pick
up.
"Earthquake precursors aren't well documented
scientifically," says Matthew Blackett, associate
professor in physical geography and natural hazards at
Coventry University. But some scientists theorise that
animals could have evolved a seismic escape mechanism,
he says. "Perhaps they detect pressure waves before
earthquakes arrive, perhaps they detect changes in
electric field as fault lines when rock starts to
compress. Animals also contain a lot of iron, which is
sensitive to magnetism and electric fields."
Positive holes could also cause certain toxic chemicals
to appear before quakes. For example, if they come into
contact with water, they can trigger oxidation
reactions which create the bleaching agent hydrogen
peroxide. Chemical reactions between the charge
carriers and organic matter in the soil could trigger
other unpleasant products such as ozone.
Meanwhile, days before the 7.7 magnitude Gujarat
earthquake in India in 2001, a surge in carbon monoxide
levels was picked up by satellites over a 100 square
kilometre (39 sq mile) region centred on what turned
out to be the epicentre of the eventual quake.
Scientists have suggested that carbon monoxide gas
could be forced out of the earth due to the build-up of
stress in rocks as quake pressure builds.
Many animals, of course, are equipped with highly
developed sensory apparatus that can read an array of
natural signals on which their lives may depend so it
seems perfectly possible that some animals may be able
to pick up any earthquake precursors. Unpleasant
chemicals could be sniffed out, low frequency waves
picked up, and ionised air sensed by sensations in fur
or feathers.
With earthquakes so difficult to anticipate, these
findings beg the question: could humans actually
predict earthquakes by animal observations, and thus be
able to warn people they are coming?
In a 2020 paper, Wikelski and his colleagues set out a
prototype for an earthquake early warning system using
animal activity monitoring sites, based on data from
his research in Italy. He estimated that farm animals
above the point of origin of the imminent earthquake
which were able to perceive it in some way would show
activity 18 hours before it hit. Animals situated 10km
(6.2 miles) away from the epicentre should show warning
signs eight hours later, followed by animals at farms
20km (12.4 miles) away a further eight hours later. "If
correct, this would indicate an earthquake is imminent
within the next two hours," he says.
Researchers will need to observe a larger number of
animals over longer periods of time in different
earthquake zones around the world before they can be
used to predict earthquakes. For this, Wikelski and
others are turning to the global animal observation
system Icarus on the International Space Station to
gather movement data for animals globally.
With earthquakes so difficult to anticipate, these
findings beg the question: could humans actually
predict earthquakes by animal observations, and thus be
able to warn people they are coming?
Icarus (International Cooperation for Animal Research
Using Space) is an initiative set up by a global
collaboration of scientists in 2002. It aims to provide
an accurate global observation system for an array of
tagged small animals (such as birds) to provide data
and clues about interactions between the planet's
animal life and its physical systems.
China, meanwhile, has already created a Quake Alert
system based at its earthquake bureau in Nanning,
monitoring the behaviour of animals much closer to the
ground specifically, snakes in farms across a wide
quake-prone region. Snakes possess a powerful array of
sensory mechanisms geared to detecting tiny changes in
aspects of their environment, and it was in part sudden
changes in the behaviour of snakes and other animals
which prompted authorities to evacuate the Chinese city
of Haicheng in 1975, just before a major quake struck
an action that saved countless lives.
"Of all the creatures on the earth, snakes are perhaps
the most sensitive to earthquakes," Jiang Weisong, then
director of the Nanning bureau, told China Daily in
2006. "When an earthquake is about to occur, snakes
will move out of their nests, even in the cold of
winter."
Earthquakes are not the only environmental dangers
animals seem to have advanced warning of. Birds are
increasingly in the spotlight for apparently being able
to detect other approaching natural hazards.
In 2014, scientists tracking golden-winged warblers in
the US recorded a startling example of what's known as
an evacuation migration. The birds suddenly took off
from their breeding ground in the Cumberland Mountains
of eastern Tennessee and flew 700km (435 miles) away
despite having just flown 5,000km (3,100 miles) in from
South America. Shortly after the birds left, a
terrifying swarm of over 80 tornadoes struck the area,
killing 35 people and causing over $1bn (£740m) in
damage.
The suggestion seemed clear the birds had somehow
sensed the twisters coming from more than 400km (250
miles) away. As to how, initial focus is on infrasound
low frequency background sounds inaudible to humans,
but present throughout the natural environment.
"Meteorologists and physicists have known for decades
that tornadic storms make very strong infrasound that
can travel thousands of kilometres from the storm,"
Henry Streby, a wildlife biologist at the University of
California, Berkeley, said at the time. He further
noted that infrasound from severe storms travels at a
frequency the birds would have been well attuned to
hearing.
Detecting variation in infrasound is also thought to be
the mechanism by which migrating birds seem able to
dodge storms on vast ocean crossings an idea now
being tested by the ongoing Kivi Kuaka study in the
Pacific Ocean.
This study was inspired by a radio programme French
navy officer Jιrτme Chardon listened to about a bird
called the bar-tailed godwit, which every year migrates
14,000km (8,700 miles) between New Zealand and Alaska.
As an experienced coordinator of rescue operations
across Southeast Asia and French Polynesia, Chardon
knew how treacherous this journey would be. Fierce
storms frequently lash the Pacific and its diaspora of
isolated island communities. So how were bar-tailed
godwits seemingly able to make their annual journeys
without being hindered by these ever-present stormy
hazards?
Set up in January 2021, the project involves a team
from France's National Museum of Natural History
fitting 56 birds of five different species with GPS
trackers to follow the routes they take across the
ocean. The International Space Station provides
oversight, receiving signals from the birds as they fly
and observing how they respond to natural hazards en
route. Their tags also collect meteorological data to
help improve climate modelling and weather forecasting
across the Pacific.
Kivi Kuaka will also look at whether bird behaviour
could warn against more infrequent hazards like
tsunamis, which are known to generate distinctive
infrasound patterns that race ahead of the actual
waves. The project aims to test birds' possible
contribution to an early warning system informing the
imminent arrival of a typhoon or tsunami, says
Francesiaz. The team is currently in the process of
retrieving GPS tags on curlews to examine whether they
reacted to an infrasound wave registered by French
meteorological balloons in the Pacific a few hours
after the recent volcano eruption in Tonga.
Samantha Patrick, a marine biologist at the University
of Liverpool, is also examining infrasound as a method
by which birds can detect and avoid natural hazards
and, by extension, perhaps alert humans too. "I think
we can say it is possible that birds can sense changes
in infrasound," she says. Patrick is currently looking
at whether albatrosses show a preference for areas of
high or low infrasound, although the analysis is not
yet complete.
Not all experts think that animal early warning systems
are a viable option for predicting disasters. And even
if they do help, animal movements alone are unlikely to
be enough to provide: people will need to rely on a
combination of early warning signals to get the full
picture.
Still, while we may not be able to talk to animals
quite yet, perhaps it's time to pay more attention to
their warnings.
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