Columnists
Let's Reminisce: The problem with invasive species
By Jerry Lincecum
Mar 5, 2019
Print this page
Email this article

The house I grew up in had eaves that were perfect locations for the type of nests that English sparrows built.  Every spring it was evident that we were surrounded by new or reconstructed nests built by these creatures, who were the most numerous of all the birds who lived around our house.  Despite their name suggesting they might have come from England, it never occurred to me that these pesky creatures might have been aliens that were deliberately introduced into this country.  Even farther from my mind was any hint that they might be considered a threat to native species of birds.     

 

I am currently reading a new book entitled “Unnatural Texas? The Invasive Species Dilemma,” by Robin Doughty and Matt Turner, and it discusses the introduction of English sparrows in the USA as an early example of invasive species.  The first of these sparrows were brought over in 1850, and there was a 20-year “craze” for them before people changed their minds, seeing them as nasty “rats of the air” and serious threats to native species.

 

This pattern of initial enthusiasm about an imported species followed by a belated recognition of serious drawbacks is one that Doughty and Turner see repeated often in the 20th century, whether the invaders are birds (starlings as well as sparrows), plants (like water hyacinth), insects (imported fire ants) or exotic wildlife (game animals from all over the world).  In recent years, for example, scientists have made us aware that wide-ranging cats (whether feral or domestic) are very destructive of our small mammals and bird populations.

 

One important thing this book accomplishes is to define and illustrate key terms in the debate over this issue.  An invasive species is defined as a nonnative species whose introduction does or is likely to cause economic or environmental harm.  A weed is any plant growing where it is not wanted, whereas a noxious weed is any plant officially designated as injurious to public health, agriculture, or wildlife.  A central concern is always the impact of alien or introduced species on an ecosystem, defined as a community of organisms and their physical environment.

 

Early settlers did not hesitate to bring with them plants and animals they found useful in the “old country,” seeing them as a way of improving the new territory.  We Texans have learned the hard way that some of the foreign species imported here have damaged both our economy and ecology.

 

Residents of one neighborhood in Austin have united to declare war on two invasive species, English sparrows and swallows, because they are a nemesis to a popular native, the purple martin.  Volunteers pull sparrow and swallow nests out of martin houses and even trap and kill the invaders because they will peck the eggs and young of the martins.  As a case study in the invasive species dilemma, Doughty and Turner review the history of how and why sparrows and swallows were initially seen as “improvements” in our bird population and why they have proved to be “avian reprobates.”

 

The chapter in this book that I found most interesting presents a case study on “Texotics,” exotic game animals from all parts of the world that are now being kept on Texas ranches.  They are valuable sources of income from hunters and photographers, who pays thousands of dollars for safaris to obtain trophies and meat or photos.  Their presence raises many issues, ranging from the impact on the ecology to hybridization with native species and the spread of some exotic diseases.  This is not a small problem, as hundreds of ranches stock scores of species, and the total number of Texotic animals in the state may be as high as one million.

 

This book is the second in the Texas A&M University Press’s Gideon Lincecum series on Nature and the Environment, endowed by myself and Dr. Redshaw.  I am confident that my great-great-great grandfather would be proud to have his name attached to this book, and we look forward to seeing more books in the series.

 

Jerry Lincecum is a retired Austin College professor who now teaches classes for older adults who want to write their life stories.  He welcomes your reminiscences on any subject: jlincecum@me.com