Small mammals killed in discarded bottles along roadsides in central Nebraska

Abstract

Littered debris along roadways traps and kills small vertebrates. In Nebraska, at least 20 species of small mammals are small enough to enter openings of discarded bottles and cans. We surveyed roadsides for littered bottles and cans containing vertebrate remains in central parts of the state. We observed 459 bottles and 278 aluminum cans along 17.6 km of roadsides in Nebraska. Littered bottles contained 41 vertebrate remains representing nine taxa of small mammals. Glass bottles contained the majority of individuals, plastic bottles had a few individuals, and no vertebrate remains were detected in aluminum cans. Harvest mice (Reithrodontomys spp.) were the most frequently observed taxa trapped in bottles, followed by short-tailed shrews (Blarina spp.). Remains of a juvenile Hispid Cotton Rat (Sigmodon hispidus) in a glass bottle suggest that more species are at risk when individuals are young. Bottles with openings higher than their base contained more vertebrates (21.1%) than those lying flat (3.8%) or those with openings facing downward (1.2%). Overall, about 5.7% of bottles had vertebrate remains in Nebraska, which is slightly greater than studies in the eastern United States. Densities of littered bottles were much lower along roads in Nebraska than roadways in the eastern United States, resulting in fewer mortalities per km. Human population density appears associated with littered debris, thus numbers of vertebrates killed in these roadside hazards likely is greater in eastern Nebraska and near population centers where most of the state’s population reside. In Nebraska, six species of small mammals are species of conservation need, and thus, at risk from littered debris. Reduction and removal of litter along roadsides not only is aesthetically pleasing, but it can also reduce mortality of small mammals and other animals, such as small insects.