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A Tale of Two Cousins

Photo Group
House Sparrow (top) and Eurasian Tree Sparrow (bottom)
Photo by: 
Mary Nemecek and Jim Gorski

Over the last 200 plus years, many plants and animals have been introduced into this country. We often don’t think of animals like Rainbow Trout, Ring-necked Pheasants or even domestic cattle as introduced species because they give us “pleasure” and are not famous for causing us problems. But what about species like Japanese Honeysuckle, European Starlings or Gypsy Moths? This is the story of two very similar birds that were introduced into this country, with drastically different outcomes.

One of the most common birds in North America, the House Sparrow (Passer domesticus), was going to be the savior of the American farmer. At least that was the plan in 1851. Like so many ecological disasters, this was done without good science to back it up and the rest, as they say, is history. The House Sparrow wasn’t just released in one place, one time. Over the following 20 years, House Sparrows were trapped and released in New York, Portland Maine, San Francisco, Salt Lake City, the Bahamas and even Brazil.

How quickly did we learn that House Sparrows only eat insects when they are feeding their young and the rest of the year they eat the very grains we brought them over to protect? By 1883, there was a bounty program put into effect and contests to see who could bring in the most carcasses. Cookbooks even included recipes for tasty House Sparrow meals.

My inspiration for writing this article wasn’t the ubiquitous House Sparrow, it was in fact the recent area sighting of its closely related cousin, the Eurasian Tree Sparrow. In 1870, this European member of the same genus, was introduced into Lafayette Park in St. Louis. I would be willing to bet that most of you have never heard of the ETS (as it is known as in the birding community). How can this be? Why did one bird spread across this continent like wildfire and the other never expand much farther than a few counties from its original release site?

The answer is very much tied to the “nature of the beasts”. While physically the two birds are very similar, it is their “attitudes” that vary greatly. The House Sparrow is a very aggressive bird that is adaptable in its nesting and dietary requirements. They start nesting as early as February and will nest 4 times in a season.

While many species of wildlife find it difficult to adapt to humans and their disturbance, the House Sparrow thrives off of it. One recent article suggests that this species and its ancestors have totally evolved with humans and are dependent on humans for their survival.

And what about the more timid cousin? Research tells us the ETS was doing quite well in the St. Louis area in its early years and even expanding. Then the bully cousin found its way into the area. The Eurasian Tree Sparrows like the Eastern Bluebird, Purple Martin and so many other cavity nesting birds were pushed around and driven out of the more urban area by the marauding House Sparrows. Today the ETS can primarily be found in pockets around the St. Louis area with a few scattered nesting reports up into southern Iowa. I seem to recall a nesting report a few years ago in southern Wisconsin.

It is an amazing tale that has turned out badly for many of our native songbirds. What can you do to help? If you have nesting boxes of any type in your yard, do not allow House Sparrows to nest in them. Monitor your boxes closely and rip out the nest as soon as they start to build them. You don’t want to be part of the problem.

It is an amazing story from so many perspectives. For someone who is a birder who enjoys seeing as many different birds as I can each time I go out, the idea of one bird being a prized find (the ETS) and the other being one of the most plentiful and least liked in North America being so closely related is amazing. Then again I can think of a cousin I find it hard to believe I am related to as well.

By Mark McKellar