Non-indigenous Species in NE
A Catalog of the Introduced Species of Birds, Fish, and Plants of the Platte River Ecosystem

Back to
How Species are Introduced

           
by
John A. Madsen and Dr. W. Wyatt Hoback
Department of Biology
University of Nebraska at Kearney

Abstract

Exotic species have been introduced both intentionally and by accident for more than a century and have dramatically changed the ecology throughout the United States, however documenting the presence of these species has not been undertaken in many regions. We cataloged the non-indigenous birds, fish, and plants found along the Platte River and the reasons for their introduction to the state. The introduction of a non-native species into a new environment has many different and potentially negative effects on the ecosystem into which they have been introduced. Our results show large differences among taxa in the numbers and reasons for introduction. Of the over 400 different birds recorded from the state of Nebraska less than 2% (7) are non-indigenous. These birds were intentionally introduced for hunting or have naturally dispersed into the state. In contrast, 30% of the 106 fish found in the Platte River are either non-native (28) or are the products of hybridization (4). These fish were intentionally introduced for recreational fishing or as food sources for game fish. More than 598 plants occur in the big bend region of the Platte River and of these 81 (13.5 %) are exotic. Most of these exotic plants were introduced accidentally as seed contaminants.

Introduction

Biological invasions have been occurring since the beginning of time. Most of the time these invasions take place on accident, but with the spread of humans, many more invasions are happening on purpose. The Introduction of exotic species can have a dramatic effect on the new ecosystem into which they have been introduced.

Purple-Loosestrife

One of the first problems that we face is defining what it means to be native or exotic. On the surface, this seems easy: Native (indigenous) is defined as a species that occurs naturally in an ecosystem and “is a species that, other than as a result of an introduction, historically occurred or currently occurs in that ecosystem”.  In contrast, an exotic species is an introduced, non-native species of plant or animal that does not occur naturally in that ecosystem.

A subset of exotic species are termed “invasive” meaning that they are alien to the ecosystem, and their introduction causes or is likely to cause economic or environmental harm. Therefore, native or indigenous species are those that have not been introduced by humans either accidentally or intentionally. Non-indigenous (non-native) applies to a species that have been introduced by humans either accidentally or intentionally (www.invasivespecies.gov/laws/, Oxford,1998).

Largemouth Bass

The objectives of this paper are to examine some biological invasions in Nebraska, and document the reasons for introduction and the effects of the introduction on the Platte River ecosystem for select species.

Materials and Methods

     We conducted literature searches using the Internet, text books, and research articles to determine bird, fish, and plant species recorded from the Big Bend Region of the Platte River. In some cases, phone interviews and email inquiries were made to obtain expert opinions on the status of an organism as native or introduced or to confirm reason for introduction. For birds, we considered only non-migratory species (those birds found in Nebraska year round). For fish, we used Nebraska Game and Parks data and limited our research to those species collected from the Platte River. For plants, we only considered those species collected from the Platte that were not cultivated by humans in an agricultural setting. Thus, crop plants such as corn and alfalfa were excluded, while introduced grass species such as smooth brome were included.

Results

Percentage of exotic species of birds, fish, and plants that occur in the Big Bend Region of the Platte River corridor in Nebraska.

Birds

     There are over 400 different birds in the state of Nebraska, only 7 (less than 2%) of which are non-indigenous. Most of the birds were introduced for hunting purposes, while the starling was introduced to the United States because it was mentioned in the work of Shakespeare (see table below). The house sparrow was originally introduced to provide insect control. Except for those birds introduced for hunting (pheasant, partridge, turkey), the non-indigenous birds found in the state were introduced into another part of the United States and spread to Nebraska through natural migration.

Fish

     There are 106 different species of fish found in the Platte River. Of these, 32 are non–indigenous and 4 represent hybrids between species. Wile some of the non-indigenous fish were introduced to our lakes and streams for sport fishing, others were introduced to provide a food source for other fish. The earliest recorded introduction of fish was as a result of an accident near the Elkhorn River in 1873.

“In the summer of 1873, the United States Fish Commission shipped a carload of 300,000 live fish from New Hampshire and Massachusetts to California. When the Union Pacific train came to the Elkhorn River east of Fremont, and in Four Mile Creek in Otoe County, the train was derailed. The fish that escaped into the river were the following: tautog, striped bass, American shad, brook trout, channel catfish, American eel, yellow perch, walleye, largemouth bass, minnows, lobsters, and oysters.” (Jones 1963)

.The majority of introduced species were released for sport fishing or to provide forage for sport fish. Most carp species were introduced to provide biological control of other species, such as aquatic weeds. The goldfish was introduced for aesthetic reasons.

Plants

     The majority of documented exotic species in Nebraska are plants. About 16% of the total flora around the Platte River (76 of 402) are exotics. These plants were introduced for many reasons including for rangeland forage, human medicine, erosion control, for ornamental purposes, and by accident.

Most of the plants along the Platte River were introduced by accident or for livestock forage.

The dandelion was intentionally introduced from Europe for human medicine and the manufacture of dandelion wine.

Acknowledgment

This work was supported by the Platte Studies Symposium grant from NCUR/ Lancy. The authors would like to thank Dr. Julie Shaffer, Dr. Kerri Skinner, and John Riggins for their assistance on the project. We would also like to thank the rest of the Lancy scholars for their support in this endeavor.

Back to How Species are Introduced