The Back Porch

The last thing birds need

The last thing birds need

This story is featured in Montana Outdoors March–April 2013 issue

While trimming a ponderosa pine in the front yard the other day, I looked up and there, slightly above eye level, was a nestling robin, its mouth open, expecting a meal.

Since I had only a small saw in my hand, the bird stayed hungry. Its behavior, however, caught my attention.

Perhaps a week old or more, the nestling spied me and knew something was amiss. First it froze, mouth agape. Then, when I looked away, the tiny bird sunk into the nest. Disappeared.

Young birds are everywhere now. Some still in nests, others learning to fly, and many not surviving.

A young bird’s life is fraught with danger. Many eggs are laid but few survive to become birds and fly away. Of birds hatched in nests on or above ground, like meadowlarks and robins, about half survive to learn to fly, when the bird is about two weeks old. Think of that: If a robin lays four eggs, only two will survive the approximately 28 days from egg to hatching to nestling to flying.

For cavity-nesting birds such as bluebirds, the success rate is better, with about two-thirds living to fledge.

Even after surviving the nest and flying away, most small birds, such as chickadees and goldfinches, don’t live more than six months to maybe two years.

Medium birds, like robins, can live four to ten years or more. Canada geese and other big birds can live for 20 years. Generally, the larger the bird, the longer it lives.

It’s that first year that takes the greatest toll on birds. Accidents, disease, migration, and winter starvation all do a number on birds. Then there’s Boots, the house cat.

House cat predation on songbirds is notoriously difficult to pin down, and various studies have produced differing figures. Yet most studies agree that in the United States each year, house cats kill millions, perhaps tens of millions of birds. Because house cats are well fed and kill just for sport, one biologist calls them “subsidized predators.”

If overfed house cats just eliminated English sparrows and starlings, no one would complain. They don’t, of course. Those tubby tabbies also kill warblers and robins and bluebirds.

Predation plays an important role in nature. One study determined that if a single pair of robins successfully raised two broods of four young each year, and all their descendants survived to reproduce, the result over ten years would be about 19 million robins. That would be intolerable.

So we can’t condemn predation. But there’s natural predation and then there’s house cat predation.

Fortunately, cats don’t always win. Several years ago, I watched a killdeer mother lure our house cat around for what seemed like weeks, putting on a crippled-bird act. During the performance her killdeer chick froze and the cat never saw it.

Cats have their place. As anyone who has lived in the country or an old house will tell you, cats are death on mice, and that’s a good thing.

But they also take their share of birds, joining the myriad other obstacles a young bird must survive to live another day.

If you have a cat, keep it indoors. Or if you let it out, keep a watchful eye.

Life’s hard enough for birds without our pets out there stalking them for sport. Though I guess you could say the same thing about me and elk. Talk about a “subsidized predator.”.Bear bullet

Bruce Auchly manages the regional Information and Education Program in Great Falls.