Small-Mammal Mortality Caused by Discarded Bottles and Cans along a US Forest Service Road in the Cherokee National Forest

Document Type

Article

Publication Date

1-1-2015

Description

Discarded containers along primary and secondary roadways trap and kill small mammals, and recently, small-mammal remains were found in containers along roadside pull-offs in more remote areas. We investigated the effects of containers along 7.9 km of a graveled, 2-lane forest service road in a remote area of the Cherokee National Forest, TN. We examined 2997 containers, of which 107 containers had 202 small-mammal skulls representing 8 species of mammals including Sorex fumeus (Smoky Shrew), Sorex longirostris (Southeastern Shrew), and Synaptomys cooperi (Southern Bog Lemming), which are deemed species of greatest conservation need and in need of management by the Tennessee Wildlife Resource Agency. Our observation of Southern Bog Lemming mortality due to container debris is the first report of collection of this species from bottles. We recorded the first observation of shrew mortality caused by aluminum cans, where 1% of all aluminum cans contained shrew skulls. Unlike previous studies, we quantified all possible containers available to trap small mammals and found glass disproportionately trapped more small mammals than plastic or aluminum. Additionally, we determined the orientation of bottle and can openings for all available containers and found that containers oriented upslope (>15°) were significantly more likely to be associated with the mortality of small mammals than containers in other orientations. We estimated that a mean of 25.6 small mammals/km were killed in discarded containers. By using bottling dates on containers, we also estimated containers were in place along the road an average of 2.16 ± 0.37 years before discovery. Only using modern bottles with dates, we conclude that the minimal potential impact on small-mammal populations was at least 973 small mammals killed per year in container debris along graveled category 3 and 4 forest service roads in the Cherokee National Forest.

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