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Are Domestic Exterminating Wildlife?

„thecutout‟ All-free-download.com By Ben Isacat August 2016

It is asserted that cats are exterminating species and should be vigorously controlled. What truth is there to this allegation? ?

Nature has made domestic cats superbly repeated so often that many people accept it adapted predators of small , like as fact: and . Predators, being at the top of the food web, are normally rare; they cannot “Domestic cats have tremendous be more numerous than the prey they feed on impacts on wildlife and are or they would die off. However, domestic cats responsible for the extinction of are unlike any other predator numerous , reptiles, and at (domestic dogs excepted): humans have made least 33 species globally.” The cats super-abundant and spread them all over Wildlife Society (2011) the globe. Domestic cats are now counted in their millions. The claim that domestic cats exterminate species drums up public hate for cats. Given that domestic cats are such passionate Professional and supposedly objective and abundant predators, scientists are researchers are not immune to . exploring their predatory behaviour to Nico Dauphine, a bird researcher who worked understand how they affect wildlife. This has at the National Zoo, Washington DC, led some researchers to claim that cats are announced at a bird conference: exterminating species. It is important to understand this claim because many people “Historically, cats have been are now demanding that cats are eliminated or specifically implicated in at least 33 severely controlled. So what is the basis for bird extinctions, making them one of this claim? the most important causes of bird extinctions worldwide” And added that, Do Cats Exterminate Species? “… removal should A much publicised and often repeated become a permanent, regular feature assertion about domestic cats is that “Feral of wildlife management.” (Dauphine et cats are responsible for the extinction of at al 2009). least 33 bird species.” This quote is from Nogales and colleagues, a group of scientists „Removal‟ in wildlife conservation is usually a reviewing the effectiveness of eradicating feral euphemism for killing. Dauphiné came to hate cats (Nogales et al 2004). This claim has been cats, tried to poison them in her

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Are Domestic Cats Exterminating Wildlife? neighbourhood and was given a suspended (www.iucnredlist.org) and Bird Life sentence in 2011 for attempted cruelty to (www.birdlife.org). I find that: animals. 1. Ziswiler does not actually list 33 So where does this claim that cats exterminate species purportedly exterminated by species originate and how true is it? cats but only 26 species, of which 18 are bird species and eight are Source 1 mammal species. I list the 18 bird Nogales and his colleagues state that their species in my Appendix, below. Of claim about cats exterminating “at least 33 bird these 18 bird species: species” comes from Lever (1994). 2. Two species are still extant (numbers Source 2 5 and 16). Lever (1994) is a book, Naturalized Animals: the ecology of successfully , 3. Four species (numbers 2, 7, 13, 18) in which he states that, are sub-species and one (number 1) is a sibling species. These do not count “According to Jackson (1977), as exterminated species because the naturalised predators have claim is for cats exterminating whole collectively been responsible for the species, not sub-varieties of species. extermination throughout the world of no fewer than 61 avian taxa, the 4. Number 14 is not recognised today as principal culprits being feral domestic a species. Cats which have caused 33 extinctions...” page 91 5. Number 17 consists of many related species. Apparently, some of these are extinct, but to keep things Source 3 uncomplicated I list them here as a So where did Jackson get his information? It single extinct species. comes from a talk he gave at a symposium about endangered birds. His talk was Thus, ten bird species listed by Ziswiler might published a year later in the book Endangered be extinct, not 33 species as claimed. But Birds (Jackson 1978) in which he presents a were any of these ten species, even including bar graph showing that cats have exterminated the sibling species and sub-species, really 33 species of birds and that the “data are exterminated by cats? summarized from Ziswiler (1967).”

Degraded Ecosystems Source 4 All the birds in Ziswiler‟s Appendix (except the So where did Ziswiler get his information? extant Eyrean Grass-wren of central ) Ziswiler lists several extinct species in the lived in tiny populations on small remote Appendix of his book, Extinct and Vanishing . This predisposed the birds to the Animals (1967). Next to each species he dangers of going extinct because a tiny marks the reasons for their extinction, such as population on a small cannot evade through destruction of the forest or through heavy predation by colonising remoter regions. introduced species. Ziswiler states that he bases his bird extinction information on a book Cats did not originally exist on any of these by JC Greenway (1958), Extinct and Vanishing islands, but people introduced them. People Birds of the World, itself based on information made many changes to these islands and gleaned from yet earlier works, and on IUCN introducing cats was only a single factor in a Bulletins for 1964, which are brief complex web of relationships. For example, in announcements, so cannot provide detailed their species factsheet for the Samoa Wood information. , Pareudiastes pacificus, (number 6) Bird Life state: Although Ziswiler states that he got his information from elsewhere, his Appendix is “Cats, , pigs and dogs have no the most compact source of information on doubt contributed to its bird species that cats are reputed to have disappearance, and may exterminated. I reappraise his list in light of up also have been a factor as it was to date data, mainly from IUCN formerly a favoured food of the human... Slash-and-burn cultivation

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Are Domestic Cats Exterminating Wildlife?

threatens remaining areas of upland extinctions, particularly on islands.” forest… Wild cattle and pigs have Nogales et al (2004). browsed the understorey and ground-cover along the main The 33 bird species purportedly exterminated range…” by cats have now jumped to “a large percentage of global extinctions”. This is a Unreliable Evidence vague and sweeping assertion, made by Too many people place too much emphasis on supposedly meticulous and objective anecdote and indirect evidence to implicate scientists. An unfortunate fact is that cats solely in extinctions. For example, researchers do not always fully scrutinise the Europeans discovered the sub-Antarctic research papers published in their field. So at Macquarie Island in 1810. According to Taylor times they are tempted to rely on the (1979), even though people introduced cats presumed veracity of an author‟s statements and other predators there, the Macquarie and simply repeat what they say in their own Island Parakeet (or Kakariki) (number 10) reports. Thus, some researchers may pass on stuck around for the next 70 years. Then in a claim that is completely without foundation. 1879 people introduced rabbits. He Nogales and co-workers repeated a claim by conjectures this increased the population, Lever, who repeated a claim by Jackson, who leading to greater predation on the Parakeets repeated a claim by Ziswiler, who got his until the birds died out. So cats seem not to information from an even earlier claim... have killed them off by themselves. A mixture Shoddy research leads to sloppy conclusions. of humans, cats, rabbits and a small bird population with nowhere else to colonise are Ziswiler’s Extinct Mammals implicated; or was this coincidental to What of the eight mammal species in Ziswiler‟s something else that really killed off the birds? Appendix that he claims cats exterminated? The real reason for the disappearance of this The same carelessness and muddle of species has not been established. extinction applies to them as it does to the birds. Loose Language Badly chosen terminology by researchers in Conclusion their publications can prompt people to believe Statements that cats are exterminating bird or that cats have exterminated species. other species are false: there is no scientific Exterminate means make extinct: no more evidence that cats have exterminated any individuals of that species live anywhere in the species. world. Extirpate means a species is killed off in a region, like an island or part of a continent, So what really exterminated these species but the species survives elsewhere. Woods et supposedly killed off by cats? Domestic cats al (2003) provide an extinction-vs-extirpation are a super abundant predator. They can mix-up: therefore be expected to kill large numbers of prey. But this is because people have made “…the Socorro dove Zenaida them so numerous. The problem therefore lies graysoni has also been driven to with humanity, as does many other problems extinction primarily by cats…“ besetting nature today. To regulate our impact on nature we have to take the responsibility of The Socorro Dove lived only on Socorro regulating ourselves and not of just blaming Island, west of Mexico. As well as introducing scapegoats. According to the World Wildlife themselves, people introduced cats, rodents Fund, humanity may be exterminating a and sheep. However, although no longer living species every five minutes or at least one on the island today, about 200 doves survive every two days. Cats cannot match this. in captivity. So the Socorro dove was extirpated on Socorro, not exterminated.

Sloppiness Another quote by Nogales and co-researchers:

“Feral cats are directly responsible for a large percentage of global

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Are Domestic Cats Exterminating Wildlife?

References 1. Dauphiné N & Cooper RJ (2009): Impacts of free-ranging domestic cats ( Catus) on birds in the : a review of recent research with conservation and management recommendations. Proceedings of the Fourth International Partners in Flight Conference: Tundra to Tropics, 205-219. 2. Jackson JA (1978): Alleviating problems of competition, predation, parasitism, and disease in endangered birds: a review. In: Temple SA (ed) (1978): Endangered Birds: management techniques for preserving threatened species. 75-84. The University of Wisconsin Press; Croom Helm Limited. 3. Lever C (1994): Naturalized Animals: the ecology of successfully introduced species. T&AD Poyser Natural History. 4. Nogales M et al (2004): Review of feral cat eradication on islands. , 18(2), 310-319. 5. Taylor RH (1979): How the Macquarie Parakeet became extinct. New Zealand Journal of Ecology, (2) 42-45. 6. The Wildlife Society: Final Position Statement: feral and free-ranging domestic cats. 2011. 7. Woods M, McDonald RA & Harris S (2003): Predation of wildlife by domestic cats in Great Britain. Mammal Review, 33(2), 174-188. 8. World Wildlife Fund. How many species are we losing? (wwf.panda.org. Accessed About the Author January 2016). Ben Isacat is a biologist with a doctorate on 9. Ziswiler V (1967): Extinct and vanishing domestic cat behavioural ecology and is the animals. Springer-Verlag, New York. You author of How to Do …legally might download Ziswiler‟s Appendix at with confidence (www.animalethics.org.uk). link.springer.com/content/pdf/bbm%3A978 Ben Isacat is his nom de plume (aka Roger -1-4615-6991-6%2F1.pdf Mammal Panaman) and he lives in Oxford, Britain. Review, 33(2), 174-188. The author has assigned this document to the public domain, meaning you are free to reproduce it

For more about judgements on domestic cats, see the article by Ben Isacat: Are Domestic Cats Killing Billions of Animals?

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Are Domestic Cats Exterminating Wildlife?

APPENDIX

Reappraisal of bird species presumed by Ziswiler (1967) as exterminated by cats

Bird Species or sub-species Sibling species or Where Extinct? (modern scientific name) sub-species? Guadalupe Storm Petrel 1 Oceanodroma macrodactyla Guadalupe Yes A sibling species (Hydrobates macrodactylus) Bonin night heron Yes. But parent 2 Bonin A sub-species Nycticorax caledonicus crassirostris species still living Red-billed Rail 3 RaIIus pacificus Tahiti Yes - (Gallirallus pacificus) Chatham Island Banded Rail 4 dieffenbachia Chatham Island Yes - (Cabalus modestus) Auckland Island Rail Adams & 5 Rallus muelleri Disappointment Living - (Lewinia muelleri) Islands. Samoa Wood Rail 6 Samoa Yes - Pareudiastes pacificus Iwo Jima Rail Yes. But parent 7 Poliolimnas cinereus brevipes Iwo Jima A sub-species species still living (Porzana cinerea brevipes) Choiseul Crested Pigeon Choiseul, Solomon 8 Yes - Microgoura meeki Islands

Bonin Wood Pigeon 9 Bonin Yes - Columba versicolor

Macquarie Island Kakariki 10 Macquarie Island Yes - Cyanoramphus erythrotis

Jamaica Pauraque 11 Jamaica Yes - Siphonorhis americana Stephen Island Wren 12 Xenicus lyalli Stephen Island Yes - (Traversia lyalli)

13 Lord Howe Grey-headed Blackbird Yes. But parent A sub-species Turdus poliocephalus vinitinctus species still living

Raiatea Thrush 14 Society Islands Not recognised as a species Turdus ulietensis

Kittlitz's Thrush 15 Peel Island, Bonin Yes - Zoothera terrestris

16 Eyrean Grass-wren Central Australia Living - Amytornis goyderi Hawaiian Honey-creepers 17 several genera: the Drepaniidae Hawaii Yes - (Drepanididae) St. Christopher Bullfinch Yes. But parent 18 St. Kitts & Barbuda A sub-species Loxigilla portoricensis grandis species still living

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