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What is the UK's most deadly animal?

By Ella Davies
Earth News reporter

Killer whale or orca (Brandon Cole / NPL)
Are killer whales appropriately named?

Red in tooth and claw not to mention venom, stings, antlers and talons: nature can be a cruel, deadly mistress.

However, "deadliness" is a subjective concept.

The animals we consider deadly to us will be harmless to many other species, and those that are harmless to us may be voracious predators in their own world.

Equally, the animals that harm the most people may not be those you first think.

Whether considering only human casualties or the overall voracity of predators, you may be surprised by some of the contenders for our respect and fear.

So which of the UK's wild species most deserves the title of "the UK's deadliest animal"?


Might our largest mammals challenge by dint of their sheer size?

There have been no recent reports of human deaths from charging deer or aggressive boar.

Our largest land mammals are associated with lethal incidents, such as traffic accidents.

A common shrew

The British Deer Society estimates that each year as many as 75,000 deer are involved in collisions, causing ten human fatalities and many more injuries.

But there are no precise figures, as accidents are not recorded by species, so it is difficult to ascertain which is the "deadliest" on the roads.

Our smallest land mammals also make surprising contenders.

Water shrews (Neomys fodiens), our largest native shrew, have a venomous bite that packs a considerable punch, even to people.

Usually, the venom paralyses freshwater shrimps, water slaters and caddis larvae.

The shrews' teeth cannot penetrate human skin, but venom in their saliva can leave a rash.

If we looked to the sea for the UK's deadliest mammal, the killer whale's name would demand a nomination.

Its common name is misleading. First, it is not a whale. Weighing 6.5 tonnes on average, it is the largest member of the dolphin family.

CBBC Live 'n' Deadly presenter Steve Backshall

Steve Backshall, presenter of the CBBC programme Live 'n' Deadly, chooses his favourite deadly encounter

Second, better described as orca, there are no reports of this huge species killing humans in the UK, though they do have impressive hunting skills and a taste for other large mammals including seals and harbour porpoises.

For that reason, the orca is the selection of Steve Backshall, presenter of the CBBC programme Live 'n' Deadly, which is choosing its deadliest UK creature.


Staying in the water, one of the largest fish in UK seas also suffers from a "bad name" when it comes to deadly reputations.

People mistakenly assume sharks have a taste for human flesh.

Yet at up to 10 metres long, the giant basking shark (Cetorhinus maximus) gently filters 1800 tonnes of water per hour for nothing bigger than zooplankton.

And there has not been a single fatal attack on a human by any shark species in the UK since records began in 1847.

Jellyfish suffer an equally undeserved status in British seas.

According to the Marine Conservation Society, the jelly you are most encountered is the harmless moon jellyfish (Aurelia aurita).

Although the rarer lion's mane jellyfish, blue jellyfish and mauve stinger can administer a painful sting, Royal National Lifeboat Institution lifeguards report no deaths on their beaches from them in 2009 or so far this year.

Portuguese man o'war
Portuguese man o'war administer a painful sting

The fearsome reputation of the Portuguese man o'war (Physalia physalis) is similarly debunked by lifeguard statistics.

Rare visitors to Britain's south coast, these animals are not jellyfish but siphonophores: colonies made up of many specialised individuals.

They use their tentacles to stun prey such as small fish and shrimps but they can also leave very painful red welts on unlucky swimmers.

For many so-called deadly animals it is not the sting that kills people, but an allergic reaction to the toxins injected by the sting.

In freshwater, tales of aggressive pike biting everything from unsuspecting wild swimmers, to cows seeking a drink, can be traced through British history.

There are no confirmed deaths from pike-inflicted injuries, however.

The same can be said for the invasive "river monster" wels catfish (Silurus glanis), despite this fish growing up to a metre and a half long in the UK, predating everything from small fish to ducks.


When it comes to identifying the UK's deadliest, it is the tiny invertebrates that may lay most claim to the title.

One of the UK's top man-killers can only be seen with a microscope.

Around 20% of the UK's population is allergic to the droppings of dust mites, according to the National Health Service, triggering conditions such as asthma.

For the 90% of UK asthma sufferers that identify dust mites as a trigger for their attacks, these microscopic creatures are potentially a big problem.

The charity Asthma UK reports 1,204 deaths from asthma in the UK in 2008, though it is difficult to directly attribute these to dust mites because attacks can be triggered by a number of irritants.

Tick safety

Another tiny harbinger of death is the tick.

Ticks feed on the blood of mammals, birds and even reptiles and can spread diseases between their hosts.

For humans, one of the most serious is Lyme disease.

There were 1472 cases of Lyme disease last year in the UK with up to a further 2000 thought to go unnoticed, due to difficulties diagnosing the disease.

Left untreated, Lyme disease can cause permanent disability. In recent years two suicides have been associated with the disease.


Maybe the answer lies not with animals deadly to humans, but those deadly to each other.

Among mammals, the common shrew (Sorex araneus) eats two to three times its body weight a day of slugs, worms and small invertebrates.

The UK's most fearsome predatory insect is most likely the green tiger beetle (Cicindela campestris).

Green tiger beetle
A green tiger beetle devours its prey

Known for their speed and aggression, tiger beetles will attempt to eat prey far bigger than themselves including caterpillars and spiders.

With powerful mandibles, tiger beetle grubs even trap and eat dragonflies.

Among birds, swifts (Apus apus) in particular have an incredible appetite owing to their high metabolism and near-perpetual aerial lifestyle.

Of Britain's raptors, the enormous white-tailed sea eagle deserves mention for its varied diet.

These reintroduced avian predators steal from other birds and feast on carrion as well as hunting fish, hare and sea birds.

There have also been reports from the Isle of Mull, Scotland of the resident eagles taking down prey as large as greylag geese.

But animals everywhere eat one another, which is why nature is described as red in tooth and claw.


So inevitably we are drawn back to those animals which are most harmful to us.

There is the UK's only venomous reptile: the much maligned adder (Vipera berus).

Although their venom is powerful enough to kill a human, there has not been a death recorded from an adder bite since 1975.

According to the Amphibian and Reptile Conservation Trust this is due in equal parts to advances in anti-venom, the fact adders will only bite when threatened and their decreasing population as their habitats are destroyed.

Bees and wasps on average kill one and four people respectively in the UK each year due to severe allergic reactions.

Herring gull, common wasp (c) E A Janes, red deer (c) Simon King /
Gulls, wasps and deer: which is the deadliest?

Some people can have a fatal allergic reaction to the invasive false widow spider (Steatoda nobilis), though so far there have been no recorded deaths in the UK.

According to the Natural History Museum, 12 species of spider in the UK can administer a significant bite to humans but their effects are usually limited to pain and swelling.

Then there are the outsiders, those unexpected animals that unwittingly cause us harm.

In recent years, for example, herring gulls have led to the death of at least one man, as the birds attacked instinctively to defend their nest.

But can a seagull be deserving of the title "UK's deadliest animal"?

Join the discussion about the UK's deadliest animals on the BBC Nature UK blog.

The Live 'n' Deadly team reveal their deadliest UK animal at 09:00 on CBBC and BBC Two, Saturday November 13th, and online at the CBBC Live 'n' Deadly website.

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