Humans, not Cats, are responsible for nearly all bird extinctions

Humans--the species responsible for widespread species loss so great as to represent an important event in earth's history around the world because of their massive interventions in the world--have a penchant for blaming others for their deeds.

Humans also naturally and often devolve into warring tribes which are prone not to think fairly about the actions of other humans.

Both of these tendencies are on display in various campaigns to blame cats for (1) killing birds and thereby, presumably, (2) resulting in the species loss of birds that has occurred in recent time.

The research behind the second of these claims is remarkably limited and flawed.

It's very clear to me that the studies claiming most cat destructivity are written by cat haters (who quite often refuse to identify as such...claiming they once had cat(s) and so on), and those who would like to divert attention from other sources of bird/wildlife extinction including especially habitat loss. 

Given what we know, I believe it is sensible to believe that human activities are directly responsible for most of the loss of bird biodiversity.  Cats are barely a factor in such extinctions globally.  Cats have only been shown to be a threat to bird species on small islands.

Cats opportunistically prey on eggs, small birds, and weak adult individuals, rarely enough enough to cancel local bird population growth.  One of the studies examined in the above link showed that cats were responsible for fewer than 3% of adult bird deaths.  On the other hand, human activities, such as increasing global CO2 concentrations, and reducing habitat areas for wildlife, have no such limits or selectivity regarding the mass mass extinctions that they are inducing.

Contrary to what is often said, the studies that are responsible for the numbers often quoted against cats themselves show that un-owned (stray and feral) cats are responsible for the vast majority of bird deaths caused by cats.

Many bird species hunted by house cats are not in fact wild bird species, but species who have entered into symbiotic relationships with human settlement, and are thus in excess of what their populations should be anyway.

Studies generally find ratios between birds killed and dragged back home.  Supposedly owned cats who ware well fed still hunt (even better, the cat haters say) but rather than eating their prey bring them back home for respect.

In my own 25 year experience as a guardian of cats with outdoor access,  I have only seen one bird dragged back home, and in that one case it looked like that bird had died from chemical toxicity of recently used arsenic based insecticides (which I quit using after that).  It looked very much to me like the cat was telling me something was wrong--and the cat was right.  The lack of seeing bird kills has not changed since I got a birdbath (which is often said to be unacceptable for people with outdoor cats.

Other people similarly report not seeing many birds among cat kills, which are more predominantly rodents and small amphibians which in most cases are in local excess due to human habitation.

Healthy adult birds are generally too fast and strong for cats.  It's true that cats love to watch any and all birds, but likely they do this instinctively seeking the low hanging fruit.  Medium and large birds can be very threatening to cats (and even people).

 Cats have been around for 80 million years and do not ever seem to have caused mass extinctions, the way that humans have, even when they were the apex predators.

When there are owned cats around, they keep away ferals and strays who would otherwise be predating over the same territories and with a serious purpose other than play/fun.  Therefore, owned cats outdoors help to control the feral cat population by limiting their access to territory.

Also in my experience, owned cats direct the bulk of their aggression not towards wildlife but towards other cats.  Cats spend endless time marking territories, defending them, and seeking and incorporating more territories when they can, much of which involves fighting other cats.  Territorial defense and expansion seems to be cats second largest activity after sleeping (which they do about 20 hours per day).  There isn't even that much time for successful bird predation, let alone extinctionary cat predation.

All this being said, I'm still interested in finding better research into this issue.  I'm fine with both TNR and euthanizing excess feral cats.  Keeping cats indoors is generally preferable but not always possible with domesticated feral cats that may demand outdoor access even to the point of self-immoliation (like one cat I have who refused to urinate inside--to the point of almost dying of urinary failure) let alone other forms of protest.