Estuary Restoration for Northern Puget Sound Birds

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Project Description

Dunlin ("Calidris alpina") at WDFW Fir Island Farm restoration area. Mount Vernon, WA

Habitat restoration is a primary conservation strategy in national and regional avian management plans (Drut and Buchanan 2000). Although the specific benefits and costs of estuarine restoration to bird populations have been debated, few empirical data exist (Koberstein et al. 2017), which hinders our ability to measure how restoration meets local, regional and national bird conservation objectives. There is strong interest in avian monitoring, as evidenced by 14 of 21 (66%) dike removal projects implemented from 1994-2016 in Puget Sound including some aspect of avian monitoring, but projects varied widely in objectives, approach, and funding (Koberstein et al. 2017). Unfortunately, the lack of information on the effects of restoration on birds often leads to controversy about the value of restoration among stakeholders (e.g., birdwatchers, hunters), producing delays and controversies that can impede the progress of restoration.

This ESRP learning project was conducted in North Puget Sound with the goal of improving our knowledge of the effects of estuary restoration, through dike setback, on avian occupancy and abundance. We chose North Puget Sound because the region supports the largest numbers of waterfowl and shorebirds in Puget Sound providing an excellent study system to investigate this question. This project was a collaborative effort with WDFW, Stillaguamish Tribe, and others (e.g., TNC, Puget Sound Bird Observatory) and builds on a previous pre- and post-restoration estuarine monitoring project in the region (Koberstein et al. 2017). We successfully implemented our protocol across a range of sites, which quantifies diverse bird taxa using differing habitats of interest, can be applied broadly, and overcomes logistic difficulties of surveying in tidal estuaries.

Findings from this study support our hypothesis on bird use in response to restoration, although further investigations are needed. We conducted surveys at sites proposed for restoration, previously restored sites, and reference sites, focusing on low marsh habitats. Occupancy and abundance at restored sites was high for dabbling duck species and strongly preferred for shorebird species, in contrast to landbirds which show lowest occupancy and abundance at restored sites. Reference marshes tended to have lower occupancy and abundance of waterbirds and increased abundance of certain landbirds, related to respective associations with vegetation cover.

Project Objectives

  • Develop and implement a sampling approach for birds at upland and tidal estuary sites
  • Quantify and compare abundance and occupancy of birds across pre-restoration, restored and reference marsh sites
  • Investigate avian-habitat relationship models that can inform restoration practitioners and habitat managers
  • Provide recommendations for strategic standardized approach for bird monitoring at estuarine restoration site

Reports and Presentations