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While domesticated cats are cherished companions, their impact on wildlife populations deserves critical attention. A 2013 study suggests that felines in the United States alone contribute to the annual deaths of 1.3 - 4 billion birds, 6.2 - 22.3 billion mammals, 258 - 822 million reptiles, and 95 - 299 million amphibians. Globally, domestic cats have been implicated in the extinction of 63 vertebrate species, primarily birds. In Australia, for instance, feral and pet cats collectively kill an estimated one million birds per day.
The population of domestic cats in the UK witnessed a significant rise, with a 4.7 million increase from 7.5 million in 2019-20 to 12.2 million in 2020-21, potentially attributed to pandemic pet acquisition. Notably, not all pet cats will remain within households throughout their lifetimes. Unlike livestock or dogs, unrestricted roaming privileges for cats present unique challenges. Additionally, current legislation does not hold owners legally responsible for their cats' behaviour, we have come to accept that cats are a law unto themselves and have a right to roam. This issue is further amplified by the estimated 1 million feral or semi-wild cats residing in rural areas, couple with an unknown but significant number of loose associations with domestic households in urban areas.
Domestic cats constitute the most abundant carnivore in the UK, exerting a significant ecological impact. Research suggests they capture an estimated 100 million prey items during spring and summer alone, predominantly targeting birds (27 million) and small mammals (69%). While these figures solely account for prey brought home, conservative estimates suggest the actual predation rate is significantly higher.
While prey composition primarily comprises common bird species like blue tits and blackbirds, artificially sustained by birdfeeders, cats also contribute to the decline of house sparrows and starlings, species already experiencing dramatic population decreases. Further, they target over 20 species of small mammals, including mice, voles, shrews, and bats. Additionally, retiles (4 species), amphibians (3 species), and even invertebrates (butterflies, dragonflies) are documented prey.
Domestic cats' ecological impact extends beyond direct predation. Their mere presence, be it visual or olfactory, can elicit significant stress responses in prey species. This, in turn, triggers a cascade of negative effects on prey behaviour, including altered foraging patterns, reduced energy reserves, diminished body condition, and compromised reproductive capacity. Furthermore, such stress can enhance vulnerability to other predators. Studies have demonstrated that even exposing blackbirds to a taxidermied cat near their nests reduced chick feeding by 33% and significantly increased predation risk from corvids (crows and their relatives). Competition for shared resources adds another layer of complexity. A mouse captured by a cat is unavailable for consumption by a hawk, impacting the entire food chain.
While domesticated cats (Felis catus), believed to have been first domesticated in the Near East around 7,500 BC, and is distinct from the UK's native species (Felis silvestris). The latter struggles for survival in remote regions of Scotland. The significant ecological impact of domestic cats on UK wildlife stems from a combination of factors: human care, unfettered roaming, and inherent predatory instincts.
Cats possess an innate hunting drive, independent of hunger. In the UK, domestic cats lack the natural predators - wolves, lynx, and wildcats - that regulate their populations and behaviour in wild ecosystems. This, coupled with human-provided food, shelter, and medical care, contributes to their abundance and hunting success.
A comprehensive study tracked 925 domestic cats across six European countries for six years to analyse their home range and potential ecological impact. The research revealed relatively localised activity, with average home ranges spanning 3.6 to 5.6 hectares (less than 14 to 22 acres). While only three individuals exhibited movements exceeding 1 square kilometre (0.39 square miles), the study highlights the potential for localised predation within gardens and neighbouring areas.
While acknowledging the joys of pet ownership, responsible care for domestic cats requires consideration of their ecological impact. Studies show that free-roaming cats contribute significantly to wildlife decline, particularly birds and small mammals.
For individuals seeking to promote healthy wildlife populations, having an alternative non-feline pet or opting not to own a cat can be an impactful choice.
For existing cat owners, implementing several strategies can mitigate their pet's impact:
Ultimately, promoting responsible cat ownership practices and advocating for cat welfare alongside wildlife conservation are crucial for achieving harmonious coexistence.
Dogs also have a significant negative impact on wildlife in the UK. This goes beyond direct predation, encompassing behavioural disruptions and displacement. Research shows that even leashed dogs may pursue or kill birds, small mammals, and even larger animals like deer and sheep.
Their mere presence can also be detrimental, particularly in sensitive areas. Studies have found that in small nature reserves, the presence of dogs alone can lead to a 40% reduction in bird species diversity across the entire reserve. Similar effects can be observed in gardens, where a dog's presence may deter birds and small mammals from establishing territories or accessing critical resources like food for their young.
Source: The Book of Wilding by Isabella Tree & Charlie Burrell
Find out more about the impact of cat and dog flea and worm treatments on wildlife> How you can help wild bees
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