Carnivorous Grey Squirrels Kill Millions of UK Songbirds Yearly . . .

(Updated by Mike Loomey on Sunday 18th August 2019)

Why Are Grey Squirrels Regarded As A Pest? ~ The Facts …

The grey squirrel is widely distributed across England, Wales & Central Scotland. It is rapidly killing off our UK native songbirds (list below), according to a study carried out by Professor Roy Brown (Visiting Professor at Birbeck College London).

The study was commissioned by the wildlife charity “Songbird Survival” and concluded that… Grey squirrels and cats kill 180 million songbirds every year. That’s 180 million bird losses out of a total natural population of around 260 Million. Alongside cats, both domestic and feral, the squirrel is the biggest predator of songbirds and farmland birds”.

The study also found that…

In areas where squirrels are common, up to 93 per cent of small birds’ nests can be raided for eggs and young by squirrels. (More on this below… ) When this is combined with sparrowhawk attacks this activity can result in total breeding failure and a loss of more than eight out of 10 adult birds“.

The professor added…

Many factors have been blamed for the decline in our songbirds in recent years. The debate about raptors has raised the issue of predation but mammal predation had largely been overlooked.”

Professor Brown’s study was based on data from multiple theme studies and single area assessments covering 115 farms in other areas throughout the UK over a period ranging from 3 to 32 years.

He discovered that the true impact of predation was much worse than expected and that mammals accounted for between one-third and three-quarters of all predation losses of the UK songbirds listed below. They carry the parapox virus which has almost wiped out their native cousins, the red squirrel. But it would seem that they have naturally developed antibodies against it. Now it seems that grey squirrels have another species in their sights.

Sciurus carolinensis ~ Problems Caused

Grey squirrels have also helped devastate our much-loved garden songbirds by killing adult birds and raiding their nests for their eggs and the young birds themselves. Not only that, they love chewing the bark off trees to get to the fleshy greenish wood underneath. So, along with bird lovers, forresters also hate them.

Professor Brown’s report claims that…

In areas where the number of grey squirrels is high, 93 per cent of small birds nests are raided. When this is combined with the sparrowhawk’s behaviour it results in the loss of 85 per cent of adult songbirds.”

Songbirds in the United Kingdom have been in decline for 30 years.

Previous studies have blamed bird losses on intensive farming the use of herbicides and pesticides plus the removal of hedges used for nesting. However, Professor Brown believes that the threat posed by grey squirrels and other animal species must also be addressed. This study concluded that…

If predators are having as bad effect as that then the answer is to look at doing something more systematic to restore the balance certainly with mammals and possible with birds of prey.

Grey squirrels carry a disease which doesn’t affect them but kills their red cousin and competes with them for food.

Sciurus carolinensis ~ Behaviour

It is quite difficult for squirrels to catch and kill flying adult birds. They are far more likely to attack bird nests, especially those that are located in trees. Of course, they do so when the mother birds are not around.  They will eat small birds, especially newly-born ones which are absolutely helpless because they don’t yet have wings capable of flight. These newborns are especially vulnerable to tree squirrels rather than grey squirrels. 

As we garden-watchers all know, squirrels are fond of eating food that was left out by humans to feed to birds. This food can range from leftover scraps on bird tables to fruit, seeds and nuts placed in older-style bird-feeding containers which don’t have built-in squirrel protection.

Squirrels have sharp vision alongside perfectly developed claws and an ever-growing dental structure that make it easier to catch and devour their prey.

They normally don’t attack rats and mice, and the reason being that most rats and mice are normally active during the night. Rats and mice are also very quick to run back to their nests when they spot danger. That makes it even more difficult for squirrels to catch them. Though squirrels have been found to attach very young mice and rats that are foolish enough to occasionally stray outside of their nests. Such rodent-attacks are not nearly as common as attacks on small helpless songbirds. 

While ground squirrels often hide behind garbage cans to watch their prey from afar, tree squirrels have great eyesight that allows them to watch small birds, mice and rats from the top of trees, then quickly pounce on them at the appropriate time.

When squirrels catch up with rats and mice or songbirds, they use their claws to grab them. This, of course, ensures that they do not run away.  

It should be noted that the hunt is mostly conducted for “sport” and not principally intended to supplement food consumption. However, squirrels will certainly eat most parts of the animals they catch if they are extremely hungry and have run out of their stock of nuts, seeds and fruit.

The Main United Kingdom Songbird Species Include…

  • Blackbird
  • Song thrush
  • Blue tit
  • Great tit
  • Robin
  • Skylark
  • Meadow tit
  • Wren
  • Dunnock
  • Chaffinch
  • Greenfinch
  • Yellowhammer
  • Reed bunting
  • Corn bunting

If you need help with identification, you may wish to check out the RSPB bird identifier.

Frequently Asked Questions

What is the grey squirrel’s scientific name?

The scientific name for the eastern grey squirrel is Sciurus carolinensis.

Can you kill Grey Squirrels UK?

The Animal Welfare Act of 2006 explains that you are not allowed to inflict “unnecessary suffering” to an animal under your “care”, like those caught in traps. So you cannot drown, suffocate or randomly bash them to death. However, a quick blow to the back of the head or shooting is legal as the animal dies quickly.

Where did they originally come from?

They originally came from the eastern United States and southeastern Canada.

When was the Grey Squirrel Introduced Into Great Britain?

It was introduced into Britain, Ireland, western North America, Italy, and South Africa in the 1800s.  To be more precise, it was first recorded in this country in the 1820s. However, it was first deliberately released onto his land (Henbury Park in Cheshire) in the year 1876. The culprit was someone called Thomas or simply T.V. Brocklehurst, who was a banker.

They are now classified as an invasive non-native species.

How long do they live? How Do You Identify them?

The grey squirrel has a silver-grey coat, with a brownish face & feet pale underside. It has a characteristically bushy tail. It is quite common to find one with reddish-brown patches. This is a natural feature of the breed. It has nothing to do with mating with the red variety.  In fact, it is easily distinguished from the red squirrel by its larger size, grey fur, and smaller ears without tufts.

Are Squirrels Carnivores? ~ Are They Carnivorous?

Squirrels are omnivores, rather than carnivorous or carnivores. This means they like to eat plants and meat. Squirrels mainly eat fungi, seeds, nuts and fruits. Unfortunately, as explained above they will also munch on UK songbirds eggs and young birds in the nest, plus small insects, caterpillars, small animals and even young snakes.

Did You Know?

Their front teeth are always growing which, if left unchecked, can pose a big problem for them. This is the reason that they always seem to be nibbling on something. It’s not just for food… It’s to grind their teeth down.

Do Magpies Kill Squirrels?

The magpie’s principal food during the summer months is grassland invertebrates. They kill beetles, flies, caterpillars, spiders, worms and leather jackets.

During the winter, the turn their attention to plant material, such as wild fruits, berries and grains, with household scraps and food scavenged from bird tables or chicken runs, pet foods etc.

Do magpies kill squirrels? Well, they will eat carrion at all times and they can catch and kill other birds. Occasionally, magpies prey on larger animals such as young squirrels and small rabbits.

Do Sparrowhawks Eat Squirrels?

A sparrowhawk’s food consists almost exclusively of birds. However, attacks on seventeen different species of mammals have been recorded. The majority pf these were voles & young rabbits. Sparrowhawks will occasionally eat shrews, young hares, weasels, moles, wood mice, rats, various species of bat. Do sparrowhawks eat squirrels? Yes, they do but less than 3% of the diet is mammals. 

Are They Territorial?

Some species regard as much as 10 hectares of land as “their patch.” They spread out at an amazing rate. One single pair of grey squirrels was released at Loch Long in Scotland in 1892. Within less than 25 years they had colonised an area of 300 square miles.


They can be extremely noisy – screeching loudly in the mating season (January to June in the UK). The female will have 1 or 2 litters each year and each will consist of between one and seven young. Most squills live in colonies or groups but some species such as Sciurus carolinensis the are solitary creatures.

Can You Keep Them as Pets?

This would be a really bad idea for numerous reasons. The gray variety is regarded as an invasive non-native species is in the international list of 100 worst invasive non-native species. In Britain, they cause immense damage to our native flora and fauna and are regarded as a “pest species”. Hence they get no protection whatsoever under the WCA. But listen to this… If you trap one, you are obliged to humanely dispatch it. You must not let it go as releasing one into the wild again is illegal.

Can They Swim?

They are not great swimmers. However, they can and do swim short distances when necessary… floods, narrow streams etc. They use the doggy-paddle swimming style. They paddle furiously with their front legs, steering with their rudder-like tails. This expends a lot of energy. It is very tiring for them and very inefficient. This might explain why you won’t find them on the Isle of Wight (Joke!)

Do they hibernate?

The short answer is “no” – They do not hibernate. You can catch sight of grey squills throughout the entire year in the UK. However, in the cold, chilly winter months they do nap for long periods. This can be for 3 or 4 days at once. This is why, unlike in spring, summer, or during autumn, you ware far less likely to see one in the garden of whilst walking your dog in the park. It is probably the reason why so many people simply assume that they are hibernating, like many other common mammals such as dormice or bats.

How do they manage to come down trees headfirst?

Squills are one of the few small mammals that can turn their back feet around so their back claws are facing up and can then grip the bark of a tree and come down headfirst without any problems.

Here are some additional statistics for you…

Average lifespan: 2-5 years but can live up to 6 years
Length: 24-28.5cm 
Tail: 19.5-24cm 
Weight: 400-650g 

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