Bird Response to Habitat Restoration at Fernhill Wetlands

In 2014-15 Clean Water Services implemented a massive habitat restoration project at Fernhill Wetlands in Forest Grove, Oregon that transformed 90 acres of unused sewage ponds into native wetland habitats designed to naturally treat wastewater. Since spring 2015 the Audubon Society of Portland (ASOP) has assessed bird response to this habitat restoration effort through a community science effort involving local birders, formal bird surveys conducted by ASOP, and analysis of historical eBird surveys conducted at the site for decades. Our general predictions were that 1) Overall avian species richness and abundance would increase, 2) Open-water dependent species would diminish in abundance, and 3) Species dependent on native wetland habitats would increase. Our key preliminary findings include: 1) Species richness was significantly higher post-restoration and is particularly accentuated during the summer season; 2) Overall species abundance does not appear to have changed significantly between pre- and post-restoration periods, however, at the individual species level we document significant shifts in abundance. Most of these shifts fit our a priori predictions. In general, most waterbird species (including Virginia Rail and Sora), wetland-dependent songbirds (including Red-winged Blackbird and Common Yellowthroat), and dabbling ducks (Mallard and Gadwall) have higher abundances post-restoration while wintering grebes and fall migratory shorebirds have lower abundances post-restoration, and 3) We provide evidence that community science eBird surveys and the formal transect surveys were directly comparable. Our findings demonstrate benefits to native bird communities that can be achieved through integration of green infrastructure strategies to manage wastewater.