Masters Defense

Impact of Great Lakes coastal wetland restoration on seasonal bird assemblages

Large-scale ecosystem restoration has become a global policy priority and carries substantial financial investment. In the United States, the Great Lakes Restoration Initiative (GLRI) is the leading large-scale restoration program targeting the health of the Laurentian Great Lakes, with coastal wetlands being one of the major habitat restoration targets. The goal of this study was to use existing data from the GLRI-funded Great Lakes Coastal Wetland Monitoring Program to investigate how Great Lakes coastal wetland habitat restoration activities impact avian taxonomic and functional metrics of biodiversity, and how that relates to the degree to which habitat was affected by restoration activities. Bird Index of Biotic Condition scores (IBC; Howe et al., 2023) increased significantly at restored coastal wetlands following restoration across both specified covariates (percent emergent vegetation area and vegetation Index of Biotic Integrity (IBI)), while most count-based taxonomic metrics and functional diversity metrics did not change significantly. We observed no significant change in bird IBC at control coastal wetlands over the same time period, suggesting a restoration site effect contributed to the increase in bird IBC observed at restored coastal wetlands. Percent emergent vegetation area was a significant negative predictor of bird IBC, while vegetation IBI was a significant positive predictor of bird IBC, suggesting that habitat quality, not simply habitat quantity, is a more important factor in the composition of bird assemblages at restored coastal wetlands. This study provides one of the first rigorous assessments of the effects of restoration actions implemented under the GLRI, and the results suggest that GLRI-funded restoration actions are linked to habitat improvement, as reflected by positive responses in bird IBC, a sensitive indicator of wetland habitat quality.