There isn't overwhelming evidence, though. Native bird life in New Zealand has dramatically increased in recent years, despite cats continuing to enjoy relative freedom and huge numbers.
I know of at least three major published studies quantifying the prey caught by domestic cats in New Zealand in Auckland, Christchurch, and Dunedin. All found significant predation of native species by cats, and that it scaled with the population numbers of those species.
On the Dunedin study:
>"A year-long study of 208 cats in urban Dunedin showed that they kill more birds, skinks, geckos, and weta than rats and mice."
>"37 Dunedin cats that were known to be prolific hunters, [...] without collars, the cats caught 378 animals, including 82 birds"
>"There is the well-documented case of a lighthouse-keeper’s cat causing the extinction of the Ste-phens Island wren. And near Tongariro National Park, one feral cat was filmed killing 102 short-tailed bats in the Rangataua forest, on the side of Mt Ruapehu, in just seven days in 2010."
This is certainly evidence that cats are killing birds but characterising the numbers in the studies you've cited as absolute decimation seems unfair. I'm genuinely surprised at how low some of these counts are. For example: 37 bell-free cats deemed "prolific killers" only managed to kill 82 birds between them over the course of a year-long study? Even allowing for a large number of unknown kills the impact here seems small.
The lighthouse story is tragic and maddening. While I opted not to adopt a new cat when my last one died, I don't support the predator-free approach to conservation.
FooHentai|4 years ago
On the Dunedin study: >"A year-long study of 208 cats in urban Dunedin showed that they kill more birds, skinks, geckos, and weta than rats and mice."
>"37 Dunedin cats that were known to be prolific hunters, [...] without collars, the cats caught 378 animals, including 82 birds"
>"There is the well-documented case of a lighthouse-keeper’s cat causing the extinction of the Ste-phens Island wren. And near Tongariro National Park, one feral cat was filmed killing 102 short-tailed bats in the Rangataua forest, on the side of Mt Ruapehu, in just seven days in 2010."
https://www.forestandbird.org.nz/sites/default/files/2018-05...
https://zslpublications.onlinelibrary.wiley.com/doi/abs/10.1...
https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486....
The success of native breeding, conservation, and re-introduction programmes has been in spite of the country's feral and domestic cats.
jephson|4 years ago
The lighthouse story is tragic and maddening. While I opted not to adopt a new cat when my last one died, I don't support the predator-free approach to conservation.
AbrahamParangi|4 years ago
corin_|4 years ago
If hypothetically (since I'm not familiar with the data) they're killing some birds but those bird populations remain healthy, is that a problem?
petre|4 years ago
soperj|4 years ago