Species → Feral Domestic Cat
Feral Domestic Cat
Felis catus
What if it disappeared?
Impact HighA systematic synthesis of all available studies estimates that free-ranging cats kill 1.4 to 3.7 billion birds and 6.9 to 20.7 billion mammals every year in the United States — most of the toll coming from unowned, feral cats rather than tracked pets — making cats the single greatest source of human-caused mortality for the country's birds and mammals.
DocumentedDetail
Loss, S.R., Will, T. & Marra, P.P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4, 1396.
The estimate combines dozens of local predation studies through a systematic-review method, with wide ranges that reflect genuine uncertainty rather than a single misleading figure. It measures direct predation mortality, not the ultimate effect on prey population sizes at the continental scale.
A global review documents impacts of the introduced cat on at least 175 vertebrate species (reptiles, birds, mammals) across at least 120 islands, with the cat identified as a direct factor in dozens of documented island extinctions — one of the heaviest extinction tolls attributed to a single introduced species.
DocumentedDetail
Medina, F.M., Bonnaud, E., Vidal, E., Tershy, B.R., Zavaleta, E.S., Donlan, C.J., Keitt, B.S., Le Corre, M., Horwath, S.V. & Nogales, M. (2011). A global review of the impacts of invasive cats on island endangered vertebrates. Global Change Biology, 17(11), 3503-3510.
The review compiles published literature on cat predation of threatened island vertebrates, island by island. Species with no native mammalian predator — a common situation on islands — are especially vulnerable, lacking evolved defensive behaviors.
Predation mortality figures are massive, but the literature remains inconclusive on the question that matters most for a continental ecosystem: does this mortality actually drive down bird population sizes over the long term, or does nature partly compensate? Evidence of a measurable demographic effect exists mainly on small islands, not in continental settings.
InsufficientDetail
High individual mortality doesn't automatically translate into population decline if the animals killed would have died from some other cause anyway (competition, disease, another predator) before reproducing — a well-documented compensatory-mortality phenomenon in population ecology, but rarely isolated specifically for the cat in a continental setting.
Documentation
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Loss, Will & Marra (2013) — The impact of free-ranging domestic cats on wildlife of the United States, Nature Communications
Accessed August 10, 2026
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Medina et al. (2011) — A global review of the impacts of invasive cats on island endangered vertebrates, Global Change Biology
Accessed August 10, 2026
Last verified: August 10, 2026