I’ve just returned from a late July meeting in Miami.  Alas, I had no free time to go birding but I certainly saw many Rock Pigeons and House Sparrows.  One expects to see these two species in any urban environment.

The two species are both introduced species.  In North America, they are rarely found very far from human-altered landscapes.  I see a fundamental difference in the habitats of these two species.

A couple of decades ago, my wife and I had the pleasure of touring Scotland.  At the northeast tip of Scotland at John O’Groats, we had the pleasure of seeing wild Rock Doves. The birds were nesting on the dramatic cliffs and permitted no close approach by humans.

Obviously, humans befriended some Rock Doves, which readily adapted to urban and agricultural habitats. Don’t expect to see Rock Doves in Baxter State Park or other areas with sparse human population density.

Finding House Sparrows in a city is a snap.  But where you would you go to find House Sparrows in the wild?  A small population of House Sparrows in the Middle East associated with natural grasslands are the only “wild” House Sparrows extant.  This population is genetically distinct from all other House Sparrows.

The vast majority of House Sparrows are associated with humans.  The “natural” habitat of House Sparrows is best described as human-altered landscapes.

With the exception of the Middle East grassland House Sparrows, these birds have married their fortunes together with humans.  The presence of humans has certainly facilitated the natural spread of the species into Europe and Asia.

The original range includes northern Africa and most of Eurasia.  The species has been introduced to North and South America, Australia and New Zealand. Pinning their success to humans, House Sparrows are doing well. They certainly outnumber humans on this planet.

House Sparrows were introduced in North America by releases of birds in Brooklyn in the fall of 1851 and the spring of 1852.  The invasion of North America was aided by subsequent introductions in San Francisco in 1871 and 1872 and in Salt Lake City in 1873 and 1874.  Now House Sparrows are found throughout the Lower 48 states except for southwest Texas and are found over much of Canada.  They have not become established in Alaska yet, likely because the relatively sparse human populations in that state to provide House Sparrow habitat.  Birders in Alaska have found occasional strays including five from northwestern Alaska that may have arrived from Siberia.

An introduced species may wreak havoc on native species. House Sparrows certainly compete with birds that live and nest in our urban, suburban and agricultural habitats.  House Sparrows readily nest in cavities.  Bluebirds, Tree Swallows and House Wrens may lose nest cavities to House Sparrows.

From personal experience, I know that House Sparrows will enter nest boxes occupied by bluebirds and kill the nestlings and then take over the nest box. An effective way to deter House Sparrows is to have the nest box openings no greater than 1.25 inches in diameter.  That opening give access to bluebirds, swallows and wrens but not the chubbier House Sparrows.

The diet of adult House Sparrows is primarily seeds. In agricultural areas, House Sparrows may become pests on cereal grains.  Parents feed their young insects.

In 1958 in China, Mao declared House Sparrows to be one of four pests that needed to be eradicated. The Chinese citizens were told to kill as many House Sparrows as possible.  Perhaps over a billion birds were exterminated.

Rice crops seemed to improve at first but the insects feeding on the crops increased rapidly in the absence of the House Sparrows.  More rice was lost to the insects than to House Sparrows. Mao reversed his position, ordering the protection of the House Sparrow. Rice crop production improved thanks to the dietary needs of nestling House Sparrows.