Evaluation of wetland mitigation in the Geater Yellowstone Ecosystem: Wildlife population and community responses
The reconstruction of US Highway 26/287 over Togwotee Pass, Wyoming, impacted or caused the loss of natural wetlands. To comply with U.S. Army Corps of Engineers permit conditions, the Wyoming Department of Transportation (WYDOT) recently completed construction or restoration of 38 mitigation wetlands along the Highway 26-287 corridor and at the aggregate pit site at the U.S. Forest Service Blackrock Ranger Station. This study provides WYDOT information on differences among wetlands created to mitigate for wetland loss (n=10), wetlands impacted but not destroyed (n=7), and natural wetlands (n=16) relative to various aspects of wildlife that use these habitats. We compare characteristics of amphibians, a pathogenic fungus, invertebrates, and birds. Created wetlands in this study area were significantly shallower than natural and impacted wetlands and had shorter hydroperiods; but impacted wetlands were similar in physical habitat characteristics to natural wetlands. Boreal toads (Anaxyrus boreas) rapidly colonized newly constructed wetlands and annual survival and recruitment rates were similar in created and natural wetlands. Boreal chorus frogs (Pseudacris maculata) were less than half as likely to occupy created wetlands as natural and impacted wetlands but population sizes were high in at least one created wetland. Barred tiger salamanders (Ambystoma mavortium) occurred in natural and impacted wetlands at similar levels, but we observed reproduction by Columbia spotted frogs (Rana luteiventris) at only one created wetland-they were common in natural and impacted wetlands. There was no difference in the prevalence of the pathogenic fungus between created and natural wetlands. Species richness of invertebrates was lower in constructed wetlands than in natural and impacted wetlands and the community composition of invertebrates differed among wetland types. Communities in created wetlands were more likely to be dominated by flying species compared to communities in natural wetlands that had more passive dispersers such as snails and clams. We recorded bird calls in two created and two natural wetlands; species richness was similar but some riparian specialists (e.g., willow flycatcher, Wilson's warbler) were not detected at either created wetland. Our results suggest that wetland creation can be an important tool for conserving wetland-dependent wildlife. Understanding how animals use created wetlands sites is a critical component to understanding the efficacy of mitigation efforts and determining alternative (e.g., earlier) endpoints. This report highlights characteristics in created sites that are advantageous to species that are perhaps non-focal, but important members of the natural community. The data presented here provide support for earlier endpoints for determining success in created wetlands and a baseline for continued monitoring of these or other created sites.
|Outlet/Publisher:||Wyoming Department of Transportation|
ARMI Organizational Units:Rocky Mountains, Southern - Biology
Rocky Mountains, Northern - Biology