The first claim in your article
The authors estimate they are responsible for the deaths of between 1.4 and 3.7 billion birds and 6.9-20.7 billion mammals annually
comes from this article (full-text), where the authors state (table 2) that domestic cats are responsible for the deaths of 1.4-3.7 billion bird deaths and a much larger number of mammal deaths in the US and Europe combined. They also state that the majority of these deaths are caused by unowned/feral cats.
This is a meta-study examining the existing literature on domestic cats with some novel analyses, and assuming that you agree with their analysis, this claim is true.
The second claim is that
Felines accompanying their human companions have gone on to prey on the local wildlife, and they have been blamed for the global extinction of 33 species.
is a slight misinterpretation of a statement in this (full-text) paper that states
Based on our database, feral cats on islands have contributed to 33 (13.9%) of the 238 global bird, mammal, and reptile extinctions (including species extinct in the wild but extant in captivity) recorded by the IUCN Red List.
What this says is that cats have contributed to, but are not solely responsible for these extinctions. Be aware though, that the paper is talking about extinctions in island fauna, which are often a special case because of restricted ranges and limited population sizes, especially when it comes to endemics. Such extinctions have been ascribed to several introduced predators (rodents, ferrets/minks), not just cats.
Baker P. J., Soulsbury C. D., Iossa G. & Harris S. . in Urban Carnivores eds Gehrt S. D., Riley S. P. D., Cypher B. L. 157–171John Hopkins University Press (2010) .
Fitzgerald B. J. . in The Domestic Cat: The Biology of its Behaviour eds Turner D. C., Bateson P. 123–150Cambridge University Press (1990) .
Lowe S., Browne M. & Boudjelas S. . 100 of the World’s Worst Invasive Alien Species: a Selection from The Global Invasive Species Database Invasive Species Specialist Group, International Union for Conservation of Nature (2000) .
Medina F. M. et al. A global review of the impacts of invasive cats on island endangered vertebrates. Global Change Biol. 17, 3503–3510 (2011) .
ADS Article Google Scholar
Crooks K. R. & Soule M. E. . Mesopredator release and avifaunal extinctions in a fragmented system. Nature 400, 563–566 (1999) .
ADS CAS Article Google Scholar
Hawkins C. C., Grant W. E. & Longnecker M. T. . in Proceedings of the 4th International Urban Wildlife Symposium (eds Shaw W. W., Harris L. K., Vandruff L. 164–170University of Arizona: Tucson, AZ, (2004) .
van Heezik Y., Smyth A., Adams A. & Gordon J. . Do domestic cats impose an unsustainable harvest on urban bird populations? Biol. Conserv. 143, 121–130 (2010) .
Article Google Scholar
Churcher P. B. & Lawton J. H. . Predation by domestic cats in an English village. J. Zool. London 212, 439–455 (1987) .
Article Google Scholar
Baker P. J., Molony S., Stone E., Cuthill I. C. & Harris S. . Cats about town: is predation by free-ranging pet cats (Felis catus) likely to affect urban bird populations? IBIS 150, (Suppl. 1): 86–99 (2008) .
Article Google Scholar
Balogh A. L., Ryder T. B. & Marra P. P. . Population demography of Gray Catbirds in the suburban matrix: sources, sinks, and domestic cats. J. Ornitholol. 152, 717–726 (2011) .
Article Google Scholar
Longcore T., Rich C. & Sullivan L. M. . Critical assessment of claims regarding management of feral cats by trap-neuter-return. Conserv. Biol. 23, 887–894 (2009) .
Article Google Scholar
Lepczyk C. A. et al. What conservation biologists can do to counter trap-neuter-return: response to Longcore et al.. Conserv. Biol. 24, 627–629 (2010) .
Article Google Scholar
Gill F. B. . Ornithology 2nd edn. W.H. Freeman Publishers (1994) .
Dauphiné N. & Cooper R. J. . Impacts of free-ranging domestic cats (Felis catus) on birds in the United States: a review of recent research with conservation and management recommendations. Proceedings of the Fourth International Partners in Flight Conference: Tundra to Tropics 205–219Partners in Flight: US, (2009) .
Banks R. C. . Human related mortality of birds in the United States. Special Scientific Report—Wildlife N. 215 US Dept. of the Interior—Fish and Wildlife Service (1979) .
Erickson W. P., Johnson G. D. & Young D. P. Jr . A summary and comparison of bird mortality from anthropogenic causes with an emphasis on collisions. Tech. Rep PSW-GTR-191 1029–1042US Dept. of Agriculture—Forest Service (2005) .
Klem D. Jr . Avian mortality at windows: the second largest human source of bird mortality on earth. Proceedings of the Fourth International Partners in Flight Conference: Tundra to Tropics 244–251Partners in Flight (2009) .
Coleman J. S. & Temple S. A. . On the Prowl. Wisconsin Nat. Res. Mag. (1996) .
Pimentel D., Greiner A. & Bashore T. . Economic and environmental costs of pesticide use. Arch. Environ. Con. Tox. 21, 84–90 (1991) .
Article Google Scholar
Manville A. II . Towers, turbines, power lines, and buildings—steps being taken by the U.S. Fish and Wildlife Service to avoid or minimize take of migratory birds at these structures. Proceedings of the Fourth International Partners in Flight Conference: Tundra to Tropics 262–272Partners in Flight: US, (2009) .
Longcore T. et al. An estimate of mortality at communication towers in the United States and Canada. PLoS one 7, e34025 (2012) .
ADS CAS Article Google Scholar
Pullin A. S. & Stewart G. B. . Guidelines for systematic review in conservation and environmental management. Conserv. Biol. 20, 1647–1656 (2006) .
Article Google Scholar
Loss S. R., Will T. & Marra P. P. . Direct human-caused mortality of birds: improving quantification of magnitude and assessment of population impact. Front. Ecol. Environ. 20, 357–364 (2012) .
Article Google Scholar
Henderson R. W. . Consequences of predator introductions and habitat destruction on amphibians and reptiles in the Post-Columbus West Indies. Caribb. J. Sci. 28, 1–10 (1992) .
Google Scholar
Nilsson N. N. . The role of the domestic cat in relation to game birds in the Willamette Valley, Oregon. Thesis Oregon State College (1940) .
Llewellyn L. L. & Uhler F. M. . The foods of fur animals of the Patuxent Research Refuge, Maryland. Am. Midl. Nat. 48, 193–203 (1952) .
Article Google Scholar
Parmalee P. W. . Food habits of the feral house cat in east-central Texas. J. Wildl. Manage 17, 375–376 (1953) .
Article Google Scholar
Hubbs E. L. . Food habits of feral house cats in the Sacramento Valley. Calif. Fish Game 37, 177–189 (1951) .
Google Scholar
Jackson W. B. . Food habits of Baltimore, Maryland, cats in relation to rat populations. J. Mammal. 32, 458–461 (1951) .
Article Google Scholar
Errington P. L. . Notes on food habits of southern Wisconsin house cats. J. Mammal. 17, 64–65 (1936) .
Article Google Scholar
Kays R. W. & DeWan A. A. . Ecological impact of inside/outside house cats around a suburban nature preserve. Anim. Conserv. 7, 273–283 (2004) .
Article Google Scholar
Blancher P. J. et al. Guide to the partners in flight population estimates database version: North American Landbird Conservation Plan 2004, Tech. Series No 5 (Partners in Flight, US, (2007) .
Barratt D. G. . Predation by house cats, Felis catus (L.), in Canberra, Australia. I: prey composition and preference. Wildl. Res. 24, 263–277 (1997) .
Article Google Scholar
Barratt D. G. . Predation by house cats, Felis catus (L.), in Canberra, Australia. II: Factors affecting the amount of prey caught and estimates of the impact on wildlife. Wildl. Res. 25, 475–487 (1998) .
Article Google Scholar
Liberg O. . Food habits and prey impact by feral and house-based domestic cats in a rural area in southern Sweden. J. Mammal. 65, 424–432 (1984) .
Article Google Scholar
Jones E. . Ecology of the feral cat, Felis catus (L.), (Carnivora:Felidae) on Macquarie Island. Aust. Wildl. Res. 4, 249–262 (1977) .
Article Google Scholar
Bramley G. N. . A small predator removal experiment to protect North Island Weka (Gallirallus australis greyi) and the case for single-subject approaches in determining agents of decline. NZ J. Ecol. 20, 37–43 (1996) .
Google Scholar
Bonnaud E. et al. The diet of feral cats on islands: a review and a call for more studies. Biol. Conserv. 13, 581–603 (2011) .
Google Scholar
Tschanz B., Hegglin D., Gloor S. & Bontadina F. . Hunters and non-hunters: skewed predation rate by domestic cats in a rural village. Eur. J. Wildl. Res. 57, 597–602 (2011) .
Article Google Scholar
Fiore C. A. . Domestic cat (Felis catus) predation of birds in an urban environment. Thesis Wichita State University (2000) .
Blancher P. J. . Estimated number of birds killed by house cats (Felis catus) in Canada. Avian Conservation and Ecology (in press) .
Page 2
Owned cats | |||
Number of owned cats in contiguous United States | 2 | Normal | Mean=84 M, s.d.=2.5 M |
Proportion of owned cats with outdoor access | 8 | Uniform | Min=0.4, max=0.7 |
Proportion of outdoor owned cats that hunt | 3 | Uniform | Min=0.5, max=0.8 |
Correction for owned cats not returning prey | 3 | Uniform | Min=1.2, max=3.3 |
BIRD return rate per cat per year | |||
US studies | 4 | Uniform | Min=1.0, max=34.1 |
US and Europe studies | 11 | Uniform | Min=4.2, max=18.3 |
All temperate studies | 17 | Uniform | Min=3.4, max=13.2 |
MAMMAL return rate per cat per year | |||
US studies | 1 | NA† | NA |
US and Europe studies | 7 | Uniform | Min=11.1, max=29.5 |
All temperate studies | 13 | Uniform | Min=8.7, max=21.8 |
REPTILE return rate per cat per year | |||
US studies | 0 | NA | NA |
US and Europe studies | 1 | NA | NA |
All temperate studies | 8 | Uniform | Min=0.4, max=2.21 |
AMPHIBIAN return rate per cat per year | |||
US studies | 0 | NA | NA |
US and Europe studies | 1 | NA | NA |
All temperate studies | 5 | Uniform | Min=0.05, max=0.5 |
Un-owned cats | |||
Number of un-owned cats in contiguous United States | 5 | Uniform | Min=30 M, max=80 M |
Proportion of un-owned cats that hunt | 2 | Uniform | Min=0.8, max=1.0 |
BIRD predation rate per cat per year | |||
US studies | 8 | Uniform | Min=24.4, max=51.4 |
US and Europe studies | 11 | Uniform | Min=23.2, max=46.2 |
All temperate studies | 19 | Uniform | Min=30.0, max=47.6 |
MAMMAL predation rate per cat per year | |||
US studies | 6 | Uniform | Min=162.3, max=354.9 |
US and Europe studies | 7 | Uniform | Min=139.4, max=328.6 |
All temperate studies | 13 | Uniform | Min=177.3, max=299.5 |
REPTILE predation rate per cat per year | |||
US studies | 1 | NA | NA |
US and Europe studies | 2 | NA | NA |
All temperate studies | 10 | Uniform | Min=4.2, max=12.4 |
AMPHIBIAN predation rate per cat per year | |||
US studies | 0 | NA | NA |
US and Europe studies | 0 | NA | NA |
All temperate studies | 3 | Uniform | Min=1.9, max=4.7 |
- *Number of studies found that include an estimate of the model parameter.
- †No calculation was conducted for this data grouping because of limited data.