ANNAPOLIS, MD (March 21, 2006) - Given time, Shakespeare's reference to the House Sparrow might have
been its ticket to a new world, for in the 1800's various American
literary societies made an effort to introduce all of the birds
mentioned in Shakespeare's works to North America. But in the case
of the House (or English) Sparrow, literary motivations appear to
have been preceded by biological experimentation. Like so many others,
this invasive exotic species was brought to the new world from the old
in order to battle an agricultural pest, the cutworm. By the time of
the heyday of introductions of Shakespeare's birds in the 1890's,
there were already millions of House Sparrows in the new world.
The House Sparrow is not a true sparrow as are the dozens of
less-familiar North American sparrows, but a weaver finch, one of a
family of old world birds known for weaving their nests. House Sparrows
are ubiquitous in North America. They are also common in many parts of
South and Central America as well as Europe, Asia, Africa and Australia.
In Maryland, house sparrows nest in every county and in nearly every
habitat, with the exception of expansive marshlands and barrier islands,
although their numbers are more concentrated near urban centers. The all
too familiar House Sparrow has been selected as the “Invader of the Month”
for March by the Maryland Invasive Species Council.
Brash, bold, and well-adapted for living among human habitation, the
House Sparrow can be found scavenging for discarded fries in fast-food
restaurant parking lots, hopping about in urban parks and streets, and
living in warehouse-style home repair retailers, where it thrives on
spilled grass seed. House Sparrows have such a long and interwoven
history of consorting with mankind that it is thought that the species
actually abandoned its previously-migratory behavior with the advent
of agricultural civilizations in the Middle East, choosing instead to
remain with a new and steady source of food.
House Sparrows scavenge farm fields and grain facilities, earning
the ire of farmers. But from an ecological perspective, it is the
nesting behavior of the House Sparrow that makes it a dangerous
invader. House Sparrows are a cavity-nesting species; that is,
they nest in holes in trees or similar structures like birdhouses.
Many native birds, including bluebirds, are also cavity nesters.
House Sparrows are extremely aggressive in their nesting behavior
and will evict the eggs and chicks of native birds from their nests,
often killing adult bluebirds who attempt to defend their young.
Among the spectrum of North American invasive species, English
Sparrows are probably a lost cause in that they appear to be so
common and widespread that there is little hope of ever removing
them from the landscape. American farmers and our native birds
are stuck with them for the foreseeable future. Recently, however,
eastern populations of this species seem to be declining - markedly
so in Maryland - probably as a result of new agricultural methods
which leave less grain in fields after harvest. It remains to be
seen whether or not falling sparrow population numbers represent
Hamlet's "special providence" for native wildlife. For more
information about House Sparrows and other Invasive Species of Concern,
visit www.mdinvasivesp.org or call the
Maryland Department of Natural Resources at 410-841-5920.