Bird response to hydrologic restoration of montane riparian meadows

Abstract

Montane riparian meadows foster biodiversity and support critical ecosystem services. A history of exploitation has left most riparian meadows throughout the Mountain West of the United States with incised channels, severely compromising their functionality. Hydrologic restoration of riparian meadows aims to increase overbank flow during spring runoff and elevate groundwater levels in the dry season. Outcome-based evaluations of the dominant meadow restoration methods are lacking and needed to ensure objectives are being met and to guide modifications where needed. We completed 1,282 point count surveys from 2009 to 2017 at 173 sampling locations across 31 montane riparian meadows in California restored using partial channel fill techniques (e.g. pond-and-plug) to evaluate the expected outcome of increased abundance of meadow birds. We analyzed trends in abundance for 12 focal bird species from 1 to 18 years after hydrologic restoration, substituting space for time in our mixed effects Poisson regression models that included covariates for the amount of riparian deciduous vegetation (RDV) before restoration, stream flow, precipitation, and temperature. We found evidence for a positive effect of time since restoration on abundance for 6 of the 12 species. Although pre-restoration RDV cover was the most frequently supported predictor of abundance, high pre-restoration cover of RDV slowed response rates for only two species, suggesting other elements of hydrologic function are also important for meadow birds. Drawing on our results, we provide suggestions for enhancing hydrologic restoration efforts in riparian meadows so that benefits may accrue more quickly to more bird species.

Wild trout and hydrologic response to restoration of incised streams with improved water use for ranching and fisheries

“…Restored wetland areas are also intended to increase winter forage for free‐ranging ungulates on the ranch, including elk, deer, moose, and antelope. Although not directly monitored in this study, such ecological benefits would be in accordance with other similar incised river restoration projects that documented positive responses in big game, bird, waterfowl, and native amphibian populations (e.g., Campos et al, 2020; Hammersmark & Mount, 2005). Moreover, as found in restored Sierra Nevada meadows (e.g., Feather River Coordinated Resource Management, 2010), this type of restoration that restores and creates wetlands has the potential to increase soil carbon sequestration, which merits further research in the face of climate change.…”

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“…The plugs force flow into the historic channel or a newly engineered channel, capture sediment, and facilitate inundation of the excavated portions of the channel, which become "ponds" (Lindquist andWilcox 2000, Pope et al 2015). Pond-and-plug restoration is intended to enhance ecosystem services including flood attenuation, water storage, water quality, and carbon sequestration, as well as to foster biodiversity through habitat improvement (Hammersmark et al 2008, Norton et al 2011, Viers et al 2013, Campos et al 2020. At the same time the Forest Service also instituted a new rest-rotation plan to manage grazing (alternating years of grazing and rest) at the restored meadows.…”

“…Pond-and-plug or other partial channel-fill measures have been implemented at dozens of meadows across California's Sierra Nevada and southern Cascades in recent decades and have been shown to increase the species richness of meadow birds, especially when riparian shrubs were already extensive prior to restoration (Campos et al 2020). However, the approach remains controversial because of its high cost, use of heavy equipment and major excavation, and creation of ponds that may spur other ecological changes or consequences, particularly at lower elevations where it may create habitat for the non-native bullfrog (Lithobates catesbianus; Pope et al 2015).…”

“…may be essential for arresting and possibly reversing the Willow Flycatcher's decline, but where willows and other riparian shrubs have been greatly reduced, we caution that such efforts alone may not be sufficient. In montane meadows, the abundance of meadow-associated bird species is influenced strongly by the structural complexity of the vegetation, particularly the presence of large patches of deciduous riparian shrubs (Campos et al 2020). With its affinity for willows, the Willow Flycatcher is unlikely to be an exception.…”

Avian diversity at Beas River conservation reserve under urbanization and intensive agriculture in Punjab, India

“…The nesting of birds in the riparian zone of the river is an essential part of sustaining the avian diversity in the area. Restoration of hydrologic function unrelated to riparian deciduous vegetation for nesting and foraging can improve habitat quality for birds (Campos et al, 2020). Therefore the present study has been done to monitor and collect the crucial information required for the development of conservation strategies for the newly built conservation reserve.…”