Distribution and Abundance of Waterfowl Species in Response to Dam Removal on the Elwha River

Our study measured distributions and abundances of waterfowl species on the Elwha River following dam removals. Removal in 2011-2014 of two large Elwha River dams initiated one of the most comprehensively studied ecosystem restoration projects ever conducted. The project has attracted particular interest in effects of marine-derived nutrients (MDN) returning to the system via anadromous fish migration. We focused on birds expected to be among the first responding to MDN return, including harlequin ducks (Histrionicus histrionicus), spotted sandpipers (Acitis macularius ), common mergansers (Mergus merganser), American dippers (Cinclus mexicanus), and belted kingfishers (Megaceryle alcyon). We hypothesized that waterfowl abundances would increase and their distributions would expand upriver in response to MDN influx. During April and May 2018, we replicated pre-dam removal waterfowl surveys conducted by Barbara Blackie (2002). We conducted waterfowl counts along shoreline transects in accessible river reaches. We estimated species-specific abundances and distributions from transect data. Our results provide direct comparison of pre-dam removal vs. early post-removal waterfowl responses in mid spring. Additional surveys are needed throughout waterfowl breeding seasons to develop a more comprehensive evaluation of waterfowl responses. Our work represents the first post-dam removal evaluation of these important MDN-dependent species, and it should be replicated regularly to track the effects of restoration of anadromous fish population abundances and distributions.