Avian Aliens

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Published on: Dec. 2, 1996

Last revision: Oct. 25, 2010

eggs and kill the nestlings of other species prior to taking over a cavity. Their bulky nests are sometimes built atop the remains of the former tenant's nest - or the former tenants themselves.

House sparrows can be a problem in bluebird or martin houses. Houses should be checked and house sparrow nests and their contents cleaned out. A house put up for bluebirds or martins and allowed to produce generation after generation of house sparrows is doing more harm than good to its intended tenants.

House sparrows can also dominate bird feeders. Bread or bread crumbs and millet are foods to avoid when house sparrows are a problem.

Because they are aliens, neither the European starling nor house sparrow are federally protected, as are virtually all other birds. Commercial sparrow traps are available that are most commonly used by purple martin landlords. Some homeowners target these two avian aliens with pellet or BB guns.

Fewer starlings and house sparrows would probably mean more bluebirds, woodpeckers, purple martins and other more desirable native birds. You should make sure that your efforts to feed and house birds are not unduly aiding or serving to boost the population of either the European starling or house sparrow.

However, not helping the avian aliens and declaring an all-out war on them are different approaches. First of all, a campaign of extermination is totally futile. Both of these birds are here to stay. Secondly, we should remember that the success of these two species is but a reflection of our altered environment.

Without the wholesale conversion of land to urban or agricultural uses, the European starling and house sparrow would not have thrived. They also serve as a continuing reminder of less enlightened times, when exotic species were routinely introduced with little regard to their impact on their new homelands.

The adaptability of birds that can make a meal of a discarded french fry, nest in the golden arches and bathe in a pothole in the road deserves at least a grudging respect. We should not blame them simply for succeeding. But don't blame Shakespeare, either.... triangle

Eurasian Tree Sparrows

by Mike Arduser

Not all avian aliens have colonized North America as rapidly and completely as the house sparrow and European starling. In fact, the St. Louis area hosts one avian alien - the Eurasian tree sparrow - that seems to be stuck in a rut.

Comely relatives of the house sparrow, Eurasian tree sparrows have been permanent residents of St. Louis since April 1870, when between 20 to 34 individuals were released in LaFayette Park.

Since that time, the bird has managed to hold on in the St. Louis area, favoring bottomlands along the Missouri River, but for some unknown reason has colonized relatively few areas outside of St. Louis County and St. Charles County (the species is established in Illinois along the Illinois River).

The Eurasian tree sparrow and the house sparrow are quite similar biologically, and in their native lands the two species are common, widespread and abundant. The factors preventing the spread of the tree sparrow in Missouri, yet enabling it to persist for over 100 years, are not known.

This alien enclave in St. Louis attracts birders from around the country, especially those who aren't expecting to travel to Eurasia anytime soon. The St. Louis area is, quite simply, the only place in North America where the Eurasian tree sparrow lives. Conservation Department areas where you can see the birds include Marais Temps Clair in St. Charles County and St. Stanislaus in north St. Louis County. The birds typically are unafraid and easy to approach. They frequent the edges of weedy fields, and often sit in trees.

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