House Sparrow

The House Sparrow is well-named, since over most of its vast range it is associated with people and our structures. Historically it occurred throughout Europe, North Africa, and much of south and central Asia. Perhaps because it was such a familiar species, it is not surprising that European colonists brought House Sparrows to every corner of the globe. As a result, they can now be found over most of the Western Hemisphere, sub-Saharan Africa, Eastern Australia, and many islands in the Pacific and Caribbean. Across the native and introduced range, sparrows remain scarce or absent in large undeveloped regions including deserts and tropical forests.

House Sparrows were first brought to the United States in the mid-1800s, and by the end of the century had spread throughout most of the lower 48 states and southern Canada (well ahead of starlings, which weren’t introduced until 1890). They first reached New Hampshire in the 1860s, probably because of nearly introductions in Boston and southern Maine. The sparrow’s expansion across the continent was aided by the abundance of food and nest sites in urban and agricultural areas alike. By the early decades of the 20th century, however, populations had started to decline, including in the native European range. The early phase of this decline has been widely attributed to the replacement of horses by the automobile, with a resultant loss of abundant spilled grain. More recent factors include declines in farmland and changes to agricultural practices. And because House Sparrows are social birds, there is even speculation that declines accelerated as there were fewer sparrows to congregate together. Declines in England have been extreme enough that House Sparrows are now a conservation priority there.

Although populations are in long-term decline on this side of the Atlantic as well, we don’t share Europeans’ concerns. As an introduced species, House Sparrows have had detrimental effects on native birds, particularly those that nest in cavities. Sparrows will evict bluebirds and Purple Martins from nest boxes, and even take over the hollow mud nests built by Cliff Swallows. Sometimes they’ll even kill young they find in nests. As a result, people who maintain man-made housing for these birds actively remove sparrow nest when they find them. This is not feasible for largely inaccessible Cliff Swallow nests, and House Sparrow remains an important treat to that species.

In city centers and most farms (i.e., those without Cliff Swallows), where their threats to native birds are minimal, House Sparrows are rarely much of a problem. Their “cheerful” chirping may be one of the few signs of avian life for residents of many urban areas, and we shouldn’t discount the possibility of them being “gateway birds” to a greater appreciation of the natural world. It’s also possible that House Sparrows are something of a “canary in a coal mine.” If a species so well adapted to living alongside people is in decline, it might be sign of some important environmental issue that we haven’t identified.