Outdoor cats and a heartbreaking bird loss

We think that someone’s cat killed the bluebird family early this spring. A pair of bluebirds overwintered in one of our nesting boxes, enduring cold and surviving on berries and suet until spring. Staking their claim in the off season appeared to give them a head start and competitive advantage. They successfully defended their home against the house sparrows that tried to dislodge them, and we watched the male bringing food to his mate while she brooded on their nest. 

Then disaster struck.

I found the male first, a broken carcass with an open chest cavity lying between the raspberry canes and the wattle fence not far from the bluebird box. One severed wing with those brilliant blue feathers lay close by. He had clearly been caught on the ground by a cat as he hunted for food for his mate. I checked the box and found her gone. 

Inside the nest were three newly hatched chicks, still warm, that had just died of exposure, and beneath them was another perfect egg. It was heartbreaking, and we buried the whole sorry mess among the raspberry canes.

There are plenty of outdoor house cats in our neighborhood, many without bells or collars, and we believe that it was one of them that attacked the birds. There was a gap beneath the fence that I have since stopped up, but they can still come into the yard from the street, the way the bears do. A few days later I saw a cat, with a bell, slinking along inside the back fence. I ran out in my stockinged feet and chased it all the way around the house, waving a stick, until it vanished across the road. 

Perhaps the owners of these cats are not aware of the carnage that outdoor cats inflict on backyard birds. It is estimated that between 100,000,000 and 350,000,000 birds are killed by cats in America every year. That works out to between one or 3.5 birds for every cat in the country — including mine who never goes outdoors without a leash. 

Our yard is set up to be a haven for birds. If you cannot contain your cat to your space, you need to be responsible for what it does in our space.

The nest box was stark and empty for a few days, and all the joy gone from our garden. Then we heard the first wrens, and they are now busily setting up house in a different box with a narrow opening suitable for them but not for cowbirds (brood parasites whose changeling eggs are raised by unwitting birds of other species). 

The orioles arrived, and are happily feeding on orange halves and whatever they are finding to eat in maple blossoms. We saw the first hummingbird, just as the bright red columbine is ready to flower. 

Two days ago, another bluebird pair ventured into the yard and attempted to colonize the old nest box. They have competition now, and so it is firmly in the clutches of a pair of bottle green tree swallows. I love those birds, too, and they have not visited our yard for years. I do not begrudge them their prize and wish them success. 

But I also put up another bluebird box, midway along the fence line between the old one and the wrens. Maybe there can be room enough for us all, for a little while at least, out here in the garden of good and evil.

Tim Abbott is program director of Housatonic Valley Association’s Litchfield Hills Greenprint. His blog is at www.greensleeves.typepad.com.