Riparian and Floodplain Restoration Guided by Avian Monitoring: Reflections from the San Joaquin River National Wildlife Refuge

Summer 2013 Ecesis, Volume 23, Issue 2

Lots of articles address the importance of adaptive management and partnerships in habitat restoration, but the concepts are critical and deserve discussion as often as possible.

April 2006, SJRNWR in Stanislaus County — This photo was taken by River Partners staff to illustrate restoration performance of 2- and 3-year old planting sites. Least Bell’s vireo was observed nesting in the older field in the background 2 months after this photo was taken.

April 2006, SJRNWR in Stanislaus County — This photo was taken by River Partners staff to illustrate restoration performance of 2- and 3-year old planting sites. Least Bell’s vireo was observed nesting in the older field in the background 2 months after this photo was taken.

For River Partners, a habitat restoration non-profit founded by farmers, adaptive management means watching the site and responding to keep the project on track. We tend to watch the development of vegetation as it relates to our performance targets (i.e. cover of weed species and native plants, presence of a diversity of natives, survival of planted trees and shrubs, etc.). However, vegetation management only describes part of a restoration project. We rely on partnerships and working groups to watch the bigger picture, the part that is tough to track — the wildlife response to restoration.

At the San Joaquin River National Wildlife Refuge (SJRNWR), a phenomenal wildlife recovery success story has been unfolding for 15 years. This article describes the specific ways that avian monitoring has guided the design and implementation of restoration in this region, but similar stories of partnership and adaptation can be told regarding small mammal monitoring and restoration (particularly with the Endangered Species Recovery Program at CSU Stanislaus), large-scale fundraising and leveraging (particularly with the USFWS and USBR), and integration of multiple overlapping conservation objectives (particularly with the California Department of Water Resources and the larger flood management community). 

In 1997, a visionary coalition of agencies, landowners, politicians, and conservation groups partnered to transition 2,500 acres of flood-prone and flood-damaged agricultural fields into an extension of the existing SJRNWR near Modesto. Acquisition of this large acreage of highly degraded lands — at a satellite location nearly an hour’s drive from the USFWS Refuge HQ in Los Banos — seemed a bit ambitious, but shortly after the acquisition was complete, the creative juices started flowing and the partnerships started solidifying.  

In 2001, PRBO Conservation Science (now Point Blue Conservation Science) began avian monitoring at the site under grants from federal partners. In 1998, River Partners and USFWS (and many others) began conceptual restoration planning and fundraising. Our understanding of Neo-tropical bird response to reforestation was in its infancy, and based wholly upon experiences from other watersheds. By 2002, the first stage of the restoration project was underway (777 acres funded by CalFED) using these guiding fundamentals: 

  1) High diversity in vegetation types will likely result in high diversity of wildlife response, and 

  2) Invasive species must be replaced with native vegetation.

We worked diligently to watch the development of the project with regard to horticultural performance of the plantings, and cost efficiencies in weed control. We learned some good lessons including how critically important light competition is to reinfestation with invasive weeds (making mugwort and other perennial herbs a fundamental component of the restoration), and how sensitive or tolerant certain riparian species are to salinity and flooding (relegating elderberries to high elevation areas only). But the ultimate goal wasn’t restoration of degraded agricultural fields to native forests; the goal was provision of wildlife habitat, and importantly RECOVERY of declining wildlife populations.

For 12 years, restoration continued in phases while Point Blue and USFWS continued monitoring avian use of the restored and remnant habitats (waterfowl and riparian songbirds) and feeding their observations back into the restoration design process. In 2005 and 2006, Least Bell’s vireo nested in 3-year old arroyo willows that we planted. This was the first nesting record in the Central Valley since 1919 (Howell et al 2012). Data was collected and recommendations for future restoration were made. In 2012, River Partners planted the final 551 acres of the Refuge, and the planting design now includes too many guiding principles to relay here. A few “Restoration Lessons Learned” are presented below. As our partners at Point Blue remind me, birds are responsive to restoration actions on a timeline that we can work with, and are relatively easy to monitor (i.e. they sing, loudly). For these reasons, avian monitoring has provided some of the most important and effective recommendations to adapt restoration approaches based on current science in the Central Valley. 

The ubiquity of community engagement in avian monitoring is another major benefit of this partnership — only birders actually want to show up regularly on a Saturday morning to walk the same site for years and years, AND report their data consistently. The unwavering efforts of the Stanislaus Audubon Society as a volunteer monitoring force in this region are beyond impressive.  

As we look forward to the restoration of the adjacent properties along the main stem of the San Joaquin River, we hope to develop these bird monitoring-restoration partnerships even further. Specifically, we hope to:

  1) Link accountings of ecosystem services to horticultural and wildlife performance data,

  2) Develop a stronger link between bird habitat observations and fish habitat values (i.e. can birds be used as indicators of broader aquatic and riparian ecosystem health), and

  3) Use this successful long-term partnership as a model to develop further partnerships and working groups that can accomplish similarly ambitious goals.

Sounds simple, right? At least we have a firm footing with which to begin. — by Julie Rentner, San Joaquin Regional Director, River Partners

Restoration Lessons Learned from Avian Monitoring at the SJRNWR
Is nest predation a limiting factor for Least Bell’s vireo recovery in the northern San Joaquin Valley?  12 years of avian data in restored areas has shown substantial nest predation by brown-headed cowbirds, but inspection of the data shows that predation rates are no different in restored and remnant habitats, and are not the primary limitation for avian wildlife recovery (Dyabala  et al in press).

The importance of concealment for nest success.  In 2009, Point Blue was able to show that nest concealment was a primary driver of nesting success for riparian songbirds at the SJRNWR (Dettling  et al 2012).  Based on similar anecdotes and these data, we’ve been working to broaden our palette of understory herbaceous plants, and now boast a solid understanding of how to establish 10 different perennial herbaceous species in and amongst trees and shrubs at very low cost.

Maintenance practices and nesting birds.  After watching an observing and discussing on the ground, we’ve developed a system regarding mechanical maintenance during the nesting season — disturbance begins early enough to preclude the arrival of nesting birds, and occurs often enough to exclude the development of nests throughout the summer. 

Species selection.  From data collected at avian monitoring locations, we know specifically which plant species are favored by several target bird species.  For example, Least Bell’s vireo nested in 3-year old arroyo willows with understories comprised of native blackberry, mugwort, and stinging nettle.  We now know that these plants must be included in designs targeting recovery of this endangered species.   

Literature cited:

Dyabala K.E., N.E. Seavy, M.D. Dettling, M. Gilbert, R.A. Melcer, and T. Gardali. Does Habitat Restoration in California’s Central Valley indirectly harm riparian bird populations by increasing Brown-headed Cowbird nest parasitism? In Press. Prepared for the California Department of Water Resources. 

Howell C.A., J.K.Wood, M.D.Dettling, K. Griggs, C.C. Otte, L. Lina, and T. Gardali. 2010. Least Bell’s Vireo Breeding Records in the Central Valley Following Decades of Extirpation. Western North American Naturalist 70(1) pp. 105-113.

Dettling, M.D., C.A. Howell, and N.E. Seavy. 2012. Least Bell’s Vireo and other Songbird Monitoring and Threat Assessment at the San Joaquin River National Wildlife Refuge 2007-2009. Report to US Bureau of Reclamation, Grant R10AP20573. PRBO Contribution #1854.