By Tracy Brighten
Research suggests owners are reluctant to accept the cat predation risk to wildlife and a cat welfare approach may be needed
Domestic cats have been introduced by humans across the world and growing cat populations are placing local wildlife under greater pressure. Cat predation compounds the survival problem by adding to habitat loss and food scarcity for some species.
Free-roaming cats on islands have contributed to the extinction of native bird, mammal, and reptile species unable to fend off this introduced predator. In mainland environments, cats are impacting local bird and mammal populations, with large numbers killed each year.
Previous studies have found that although cats generally only catch one or two prey items per month, and not all cats hunt, high density cat populations can have a significant impact on wildlife numbers over time. Cats in urban areas can reduce bird numbers faster than some species can breed.
This latest study, published in Ecology and Evolution, will inform management strategies to reduce cat predation, showing prevailing attitudes that need to be overcome to protect wildlife.
“There is a clear need to directly address the perceptions and opinions of cat owners,” said lead author Dr Jenni McDonald from the University of Exeter’s Centre for Ecology and Conservation.
Researchers studied cats in two U.K villages to determine the attitude of cat owners to their pet’s predatory habits. They found that irrespective of prey numbers brought home by their cat, owners did not believe cats are harmful to wildlife.
Owners were against suggested measures to restrict their cat’s freedom to reduce the impact on local wildlife. However, they would consider neutering, which is associated with cat welfare.
Co-author Professor Matthew Evans, Professor of Ecology at Queen Mary University of London, said lack of awareness and owner opposition to keeping cats indoors makes it difficult for conservationists.
Owners in denial over cat’s conservation impact
Owners in this study did not accept their cat’s potential conservation impact, believing that predation is part of the ecosystem, said Evans.
Predation is a natural behaviour, but introduced predators can wreak havoc on wildlife in both urban and rural areas.
In the U.S, a study estimated that the deaths of 1.3 to 4 billion birds and 6.3 to 22.3 billion mammals annually were caused by free-ranging domestic cats, which may exceed deaths caused by road accidents, building collisions, or pesticide poisoning. Un-owned cats (strays fed by humans, as well as feral cats) were found to be a greater problem than owned pets, possibly because 50% to 60% of cat owners in the U.S keep their cats indoors.
In the U.K, there are over ten million domestic cats spread across 23% of households. The Mammal Society estimates 275 million prey items are caught each year and 55 million of those are birds. Birds most frequently killed are house sparrows, blue tits, blackbirds, song thrush and starlings. Estimates are based on returned prey, but other research shows that cats bring home less than a third of their total kill.
The RSPB reports that although there is no scientific evidence that cat predation in the U.K is affecting bird species, some British garden birds are in decline and cat predation impacts those species already under pressure. According to the RSPB, domestic cats will catch prey regardless of whether they intend to eat it. Mice and voles make up the majority of their prey, with birds around 20%. Most birds are taken around dawn or dusk, in the breeding season, or in winter when food is scarce and birds spend more time on the ground.
Cats kill endangered national icon
A similar denial exists in New Zealand. The kiwi is the national icon, yet this gentle, flightless bird could be extinct on the mainland within 50 years. Although pet dogs kill more adult kiwi, chicks are killed by cats roaming in kiwi territory during the breeding season. Owners cannot control where their cat goes, and domestic cats wearing radio transmitters were found to roam up to 20 kms from home.[i] Partners in crime, stoats and cats kill a staggering 70% of kiwi chicks before they reach 6 months of age.
The New Zealand dotterel is another endangered native threatened by predation and breeding disturbance. In daytime, cats take eggs from nests in the sand, and after dark they ambush sitting females. Unfledged chicks are easy prey – one cat can wipe out all the nests near its home in a single night.
The average cat kills 13 birds a year.[ii] A WSPA pet survey reveals New Zealand has 1.4 million cats, so the death toll is considerable.[iii] In our constructed animal hierarchy, people value pets highly, but wildlife is demoted and birds are way down the pecking order.
We have a moral obligation to be responsible pet owners and look beyond the interests of our own household. It may be distasteful, but Kitty is equally at home tearing apart a fledgling as she is snuggling up on the sofa.
Zealandia in Wellington is the world’s first fully-fenced eco sanctuary and New Zealand’s only city-centre wildlife haven. The 225 hectares of native bush and river habitat is home to 40 native and endemic bird species, but these birds are at risk from the growing number of domestic cats, as well as feral populations.
Cat registration scheme
The Morgan Foundation submitted a proposal to Wellington City Council for a cat registration scheme involving micro-chipping pet cats. This would allow lost cats to be returned to their owners and strays taken to the SPCA and re-homed, or humanely euthanised. Australia already has a registration scheme, but the proposal has received widespread criticism from NZ cat owners. A night-time curfew, as well as a limit of three cats per household has also been proposed.
If governments, councils, and cat owners refuse to listen to scientific and conservationist recommendations, the efforts of wildlife organisations and volunteers to preserve native species will be in vain.
Birds can be better protected if responsible owners keep their cats inside between dusk and dawn and ensure they wear a bell collar if they are outside in daylight. Bells can reduce bird catch rates by 50%.[iv]
Collars protect cats as well as wildlife
A study published in Journal of the American Veterinary Medical Association found that cats accepted wearing a collar more readily than owners expected. Researchers at Ohio State University in the U.S found that 3 out of 4 cats wore a collar for the entire 6-month study period.
Led by Linda Lord, assistant professor in the department of veterinary preventive medicine, the study aimed to show that collars are a viable method of identification, invaluable in re-uniting lost cats with owners. Whilst there was a small risk (3%) of the collar getting caught, Lord said the risk of the cat getting lost was far greater.
The best protection for wildlife though is to keep pet cats indoors. A University of Sheffield study suggests that birds are not only at risk of being attacked. A cat’s presence (a stuffed model) was shown to change a blackbird’s behaviour so that it made loud alarm calls to defend its nest, attracting the attention of predator crows and magpies. The blackbirds also fed their chicks less often after the cat threat had gone.
Reducing cat predation by regulating cat ownership is a sensitive issue and few governments have been prepared to risk unpopularity, so voluntary co-operation is key.
Domestic cat welfare
Dr Jenni McDonald believes cat welfare is the way to encourage owners to get involved in reducing wildlife deaths caused by domestic cats.
Free-roaming cats are at risk of becoming lost, injured, diseased, pregnant, or run over. Keeping pet cats inside makes sense from an animal welfare point of view, as well as minimising suffering and healthcare costs to owners. Human welfare may also persuade.
Outdoor cats pose a risk to children and pregnant women by excreting bacteria that can cause toxoplasmosis. Toxoplasmosis has also been found in marine mammals with cat faeces in estuaries and coastal waters the suspected source.
Feral cat populations that can quickly spiral out of control promote the spread of the Toxoplasma gondii parasite. De-sexing cats reduces the chance of unwanted kittens that become wild.
Preventing unplanned cat litters and strays
Research published by the British Medical Journal reports cat owner’s ignorance of their pet’s sexual habits is causing soaring numbers of unwanted kittens. The study suggests that 200,000 litters every year – an estimated 850,000 kittens – are unplanned in the UK, with up to 150,000 cats believed to have ended up in animal welfare centres in 2009-2010.
The study authors said that unplanned litters increase the health risk to mother and kittens, especially with inbreeding. In the 715 cat-owning households studied, almost 80% of litters were unplanned.
Knowledge on a cat’s sexual maturity and welfare was found to be poor, with many owners unaware that a four month old kitten can get pregnant, and that there is no evidence of any health benefit from a cat having a litter before being neutered. The authors suggest that neutering early would have the biggest impact on unwanted litters.
Cat Tracker project
A Cat Tracker project run by Your Wild Life and The North Carolina Museum of Natural Sciences aims to find out what your cat gets up to when it leaves home. Using GPS collars on domestic cats, this project will provide much needed data on risks to wildlife from cat predation as well as risks to cats from parasitic diseases.
Intrinsic value in nature
As well as promoting the benefits to cat owners of keeping cats inside and neutering, attitudes could also be changed by raising public awareness of nature’s value to mental health and wellbeing. Conservation organisations are encouraging people, families and communities to get involved – the RSPB with their Give Nature a Home campaign and The Wildlife Trusts with Every Child Wild and the Audubon Society with Get Outside.
Naturalist and broadcaster Sir David Attenborough knows first-hand the intrinsic value of nature, birds in particular, “What wild creature is more accessible to our eyes and ears, as close to us and everyone in the world, as universal as a bird?”[v]
It is possible to be a cat-lover and a wildlife enthusiast as a responsible cat owner who balances the welfare of cats with wildlife. If we make a place in our hearts for wildlife alongside cats, we can help stop the decline in species they prey on.
[i] Metsers, E.M. (2010). Cat-exclusion zones in rural and urban-fringe landscapes: how large would they have to be? Wildlife Research, 37, pp. 47–56.
[ii] Van Heezik, Y. (2010). Do domestic cats impose an unsustainable harvest on urban bird populations? Biological Conservation. 143, pp. 121–130.
[iii] WSPA (2011, August) New Zealand Survey Reveals A Nation Of Animal Lovers And Pet Owners.
[iv] Gordon, J.K. (2010). Belled collars reduce catch of domestic cats in New Zealand by half. Wildlife Research, 37, pp. 372.
[v] Attenborough, David. (n.d.). Retrieved October 08, 2013, from http://www.brainyquote.com/