Many populations of birds in the U.S. have been declining for decades. A recent assessment ( estimates that one in every four birds that existed in 1970 is now gone. That’s nearly 3 billion birds lost from our avifauna.

Unfortunately, birds are killed in a huge variety of ways. Those losses also can occur over an enormous space, and, of course, during any time of the year. Consider the Swainson’s hawks that I’ve written about several times before. They travel to and from Argentina every year and have to avoid being electrocuted, shot, poisoned, whacked by a vehicle or a wind turbine blade, or flying into a communication tower or its guy line.

If they successfully navigate that gauntlet, they risk their habitat being gone when they arrive in the spring for breeding or in the fall for wintering. Breeding habitat loss for this species is very real in the Treasure Valley. Swainson’s’ hawks prefer clumps of tall trees for nest sites, surrounded by open fields and pasture lands where they hunt for prey. But you know what’s happening to exactly this habitat all around our area — it’s going away … fast.

Habitat loss has long been the No. 1 cause of population declines for most species in most parts of the world. I hasten to add that other particular sources of mortality, e.g., shooting, can be much more serious for a given species in a given spot. See my column on long-billed curlews (March 17, 2021). But on the whole, losing habitat for breeding, for stopover during migration, and for wintering is the biggest issue.

Habitat loss is an indirect source of mortality. That is, we are not killing birds directly by cutting trees and building more condos. We are only impacting them in the long term. Direct sources of mortality are those things we do that kill birds directly.

Guess what the No. 1 source of this mortality is in the U.S.? Hint: it’s also the No. 1 cause in Canada. Answer? Cats. Cats kill an estimated 2.4 billion birds each year in the U.S., far more than window collisions, tower collisions, electrocution, and other causes.

There are over 100 million feral and outdoor cats in our country. So, it’s not just those wild cats roaming the countryside in rural areas. It’s those cats that we just let out the back door. Some cats deliver dead birds to their owners or drop them on the doorstep. But many do not. Research has shown that even if you have never seen your cat with a bird, it’s highly likely it’s killing birds out of sight.

Research has also shown that declawing cats or putting bells on them does little or nothing to reduce their ability to kill things. They have evolved to be skilled predators and they are.

Because the needs for bird conservation far exceed our capacity (money, people, time, and authority) to do something, we follow three steps in choosing what conservation actions we’ll take. First, we look at all the species and figure out which ones most need help. Population trend and population size are two important factors, with obvious implications. Small populations with downward trends are in the worst situation.

Other metrics are the size of the region in which they breed and winter. Species that are spread out over a big area are more likely to do well into the future than those with small ranges. Two final pieces are estimates about the threats during the breeding and wintering seasons. These can be quite different for species that migrate.

The second step, for those species that do need help, is to figure out what the problem is. When and where is the mortality happening? This almost always requires time and more resources. If it requires research in a difficult place, answers might take many years to discover.

Third, once we figure out which species need help, what the problem is, and when and where to do it, we act. That is simple in concept but can also be difficult, expensive, time-consuming, or, usually, all three.

Cats present a good example of this complexity. Problem: Cats are killing billions of birds a year. Solution: get rid of feral cats and keep pet cats in the house. Few solutions to any problem are so simply expressed. But easy to put into words does not mean easy to do. The problem is not scientific, it’s social. What’s new?

First, feral cats could be live-trapped and then adopted out to good homes. This is how the Bureau of Land Management has tried to deal with wild horse problems on public lands. This has not solved the wild horse problem, and it won’t solve the feral cat problem. Not too many people want a wild, adult cat.

Another option is to take lethal action against feral cats, but people go crazy over this idea. This strikes me as seriously inconsistent because many Americans shoot gophers, whistle pigs, badgers, and coyotes for fun. They shoot wolves and crows in season, and other species that they do not plan to eat.

The federal government’s Animal and Plant Health Inspection Service (APHIS) killed over 62,000 coyotes in the U.S. just in 2019. Hundreds of thousands of other animals are killed annually for various reasons. Guess what? APHIS also took out 496 feral cats that year. That’s a start.

Another proposed solution to feral cats is to trap, neuter, and release them. This may slow cat population growth but does not stop them from continuing to kill birds and other native species. Remember, cats are not from here. They are an exotic species. And feral cats are also invasive, like cheatgrass, thistles, goat’s head, and other weeds, invading more habitat and damaging more native ecosystems as time goes by.

But let’s look at an even more frustrating problem — pet cats that are let outdoors. To repeat the simple solution — keep your cat indoors. Solutions have been to educate cat owners, to appeal to their sense of decency. It’s well established that cats who go outdoors are more at risk of being injured, catching a disease, and being killed by cars, coyotes, great horned owls, and other sources of mortality. Although some of my friends around the country see cats when they’re out birding, I never do. I think the reason around here is simple — coyotes.

One nice solution that’s emerged recently are catios. These are simple, screened outdoor enclosures that allow an indoor cat to go outdoors without risking itself or the birds. In some northwestern cities there are catio tours where you can see how different people have solved this problem. In Portland, you can get a catio tour combined with a brewery tour. Talk about win-win!

It strikes many of us as wrong that cats get a pass from regulations in many cities. Cats can run around the neighborhood however they like, pooping in your garden and killing birds around your feeders. We don’t allow dogs, horses, cattle, pigs, goats, or any other domestic animal to run amok. All other animals have to be fenced in, on a leash, or otherwise under supervision. I have people riding horses and walking sheep in my neighborhood, but they don’t run loose, jump my fences, and kill things. Let’s simply treat cats like we do other domestic animals. That would be a wonderful change for birds and other small wildlife.

You can get more information on the cat problem at the American Bird Conservancy ( For a deep dive, check out the book, “Cat Wars: The Devastating Consequences of a Cuddly Killer” by Pete Marra and Chris Santella (2016). Among many details, they discuss the 33 species of wildlife that have been driven to extinction by cats.

We’ve had cats in our house since 1974. Our last little female, Ginger, died at the age of 19. Our previous cat, Millie, made it to 21. We are good to our pets, and they like it here. Many of our cats over the years have gone in and out, but I won’t have another cat that goes outside. Too many birds are dying from too many causes. I won’t risk contributing to another death. Join me.

You can email Terry at:

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