Keeping pet cats indoors reduces bird deaths and helps protect declining migratory bird populations [1].
This shift in pet ownership is critical because free-roaming cats hunt as an instinctual behavior, adding pressure to avian species already struggling to survive. With migratory patterns under threat, the impact of domestic predators can accelerate the collapse of local ecosystems.
Ornithologist Peter Marra discussed the issue in a recent segment with PBS NewsHour host William Brangham [1]. Marra said that the hunting behavior of cats is not driven by a need for food. "Hunting is in the cat's nature," Marra said. "It does it, not because it's hungry, but because it's what it does" [1].
The scale of the impact is significant. Hundreds of millions of birds and small mammals are killed annually by free-roaming cats [2]. This predation occurs globally, though data is particularly concentrated in the U.S. and North America [1, 2].
These losses are particularly damaging given the current state of global bird populations. More than half of all migratory bird species are currently in decline [1]. A recent study published in the journal Nature highlighted these trends, emphasizing that human-managed pets are a primary driver of mortality for these vulnerable species [1].
Advocates suggest that managing the environment, such as keeping cats inside or using protected bird feeders, can mitigate these losses. By removing the predatory threat from the immediate environment, homeowners can provide a safer corridor for birds during their seasonal migrations [2, 3].
“"Hunting is in the cat's nature. It does it, not because it's hungry, but because it's what it does."”
The data suggests that domestic pet management is no longer just a matter of animal welfare, but a component of biodiversity conservation. Because migratory birds are already facing systemic declines, the additive pressure of domestic predation can push vulnerable species toward local extinction.
