nesting islands

The South Bay Salt Pond Restoration Project aims to restore many former salt production ponds, now managed for wildlife and water quality, to tidal marsh. However, because managed ponds support large densities of breeding waterbirds, reduction of pond habitat may influence breeding waterbird distribution and abundance. We investigated habitat use associated with breeding, feeding, and roosting behaviors during the breeding season for American Avocets (Recurvirostra americana), Black-necked Stilts (Himantopus mexicanus), Forster’s Terns (Sterna forsteri), and Caspian Terns (Hydroprogne caspia) in south San Francisco Bay in 2019 after substantial tidal marsh restoration, and compared results to a 2001 survey (before restoration). In 2019, managed ponds (26% of currently available habitat) were selected by waterbirds engaged in breeding behaviors (> 39% of observations), foraging (> 42%), and roosting (> 73%). Waterbirds avoided tidal habitats (43% of available habitat), comprising < 17% of observations of breeding behavior, < 28% of foraging observations, and < 13% of roosting observations. Waterbird densities increased in managed ponds between 2001 and 2019, and decreased in active salt ponds, especially among feeding Avocets (92% decrease) and Stilts (100% decrease). Islands were important for waterbirds observed breeding and roosting (45% of Avocet and 53% of Tern observations). Avocets and Stilts fed primarily on wet bare ground (65% and 58%, respectively), whereas feeding Forster’s Terns and Caspian Terns used mostly open water (82% and 93%, respectively). Within ponds, Avocets were associated with islands (131 m closer than expected). Stilts and Forster’s Terns were also associated with islands (68 m and 161 m closer than expected), except when feeding (1 m closer and 90 m farther than expected). Avocets and Stilts were associated with pond levees (39 m and 41 m closer than expected), but Forster’s Terns were not (9 m closer than expected). Our results emphasize the importance of managed ponds for breeding and foraging waterbirds, including islands for breeding and roosting and levees for foraging.

Keywords

birds

waterbirds

Pond Complex

Alviso

Eden Landing

Ravenswood

Content available here

eScholarship link to paper

South Bay Salt Pond Restoration Project: Annual Report 2013

ariela — Thu, 23 Jun 2022 20:06:07 +0000

South Bay Salt Pond Restoration Project: Annual Report 2013

2013 Annual Report cover

ariela Thu, 06/23/2022 - 13:06

Document Category

Progress Reports

Author(s)

SBSP Project Management Team

Date

03-2014

Summary

A yearly snapshot of Project milestones and assessment of progress toward meeting restoration, public access and flood management goals

Keywords

trail use/public access

South Bay Salt Pond Restoration Project: Annual Report 2012

ariela — Thu, 23 Jun 2022 19:30:08 +0000

South Bay Salt Pond Restoration Project: Annual Report 2012

2012 Annual Report cover

ariela Thu, 06/23/2022 - 12:30

Document Category

Progress Reports

Author(s)

SBSP Project Management Team

Date

03-2013

Summary

A yearly snapshot of Project milestones and assessment of progress toward meeting restoration, public access and flood management goals

Keywords

trail use/public access

Breeding Waterbird Populations Have Declined in South San Francisco Bay: An Assessment Over Two Decades

ariela — Tue, 28 Sep 2021 17:03:30 +0000

Breeding Waterbird Populations Have Declined in South San Francisco Bay: An Assessment Over Two Decades ariela Tue, 09/28/2021 - 10:03

Document Category

Scientific Reports

Author(s)

Date

2021-09

Summary

In south San Francisco Bay, former salt ponds now managed as wildlife habitat support large populations of breeding waterbirds. In 2006, the South Bay Salt Pond Restoration Project began the process of converting 50% to 90% of these managed pond habitats into tidal marsh. We compared American Avocet (Recurvirostra americana) and Black-necked Stilt (Himantopus mexicanus) abundance in south San Francisco Bay before (2001) and after approximately 1,300 ha of managed ponds were breached to tidal action to begin tidal marsh restoration (2019). Over the 18-year period, American Avocet abundance declined 13.5% (2,765 in 2001 vs. 2,391 in 2019), and Black-necked Stilt abundance declined 30.0% (1,184 in 2001 vs. 828 in 2019). Forster’s Tern (Sterna forsteri) abundance was 2,675 birds in 2019. In 2019, managed ponds accounted for only 25.8% of suitable habitats, yet contained 53.9%, 38.6%, and 65.6% American Avocet, Black-necked Stilt, and Forster’s Tern observations, respectively. Conversely, tidal marsh and tidal mudflats accounted for 42.9% of suitable habitats, yet contained only 18.4%, 10.3%, and 19.8% of American Avocet, Black-necked Stilt, and Forster’s Tern observations, respectively. Using a separate nest-monitoring data set, we found that nest abundance in south San Francisco Bay declined for all three species from 2005–2019. Average annual nest abundance during 2017–2019 declined 53%, 71%, and 36%, for American Avocets, Back-necked Stilts, and Forster’s Terns, respectively, compared to 2005–2007. Loss of island nesting habitat as a result of tidal marsh conversion and an increasing population of predatory California Gulls (Larus californicus) are two potential causes of these declines. All three species established nesting colonies on newly constructed islands within remaining managed ponds; however, these new colonies did not make up for the steep declines observed at other historical nesting sites. For future wetland restoration, retaining more managed ponds that contain islands suitable for nesting may help to limit further declines in breeding waterbird populations.

Hartman, C. A, Ackerman, J. T, Schacter, C. R, Herzog, M. P, Tarjan, L. M, Wang, Y., et al. (2021). Breeding Waterbird Populations Have Declined in South San Francisco Bay: An Assessment Over Two Decades. San Francisco Estuary and Watershed Science, 19(3). http://dx.doi.org/10.15447/sfews.2021v19iss3art4 Retrieved from https://escholarship.org/uc/item/16n259mc

Keywords

Pond Complex

Alviso

Eden Landing

Ravenswood

Content available here

San Francisco Estuary and Watershed Science, Volume 19, Issue 3

Evaluation of Caspian tern (Hydroprogne caspia) and snowy plover (Charadrius alexandrinus nivosus) nesting on modified islands at the Don Edwards San Francisco Bay National Wildlife Refuge, California—2015 Annual Report

Dave Halsing — Wed, 22 Jan 2020 21:19:20 +0000

Evaluation of Caspian tern (Hydroprogne caspia) and snowy plover (Charadrius alexandrinus nivosus) nesting on modified islands at the Don Edwards San Francisco Bay National Wildlife Refuge, California—2015 Annual Report Dave Halsing Wed, 01/22/2020 - 13:19

Document Category

Scientific Reports

Author(s)

Date

2016-03-24

Keywords

Pond Complex

Alviso

Ravenswood

Content available here

USGS Publications

Evaluation of Caspian tern (Hydroprogne caspia) and snowy plover (Charadrius alexandrinus nivosus) nesting on modified islands at the Don Edwards San Francisco Bay National Wildlife Refuge, California--2016 Annual report

Dave Halsing — Wed, 22 Jan 2020 21:11:36 +0000

Evaluation of Caspian tern (Hydroprogne caspia) and snowy plover (Charadrius alexandrinus nivosus) nesting on modified islands at the Don Edwards San Francisco Bay National Wildlife Refuge, California--2016 Annual report Dave Halsing Wed, 01/22/2020 - 13:11

Document Category

Scientific Reports

Author(s)

Date

2017-05-08

Keywords

Caspian tern

snowy plover

nesting islands

Pond Complex

Alviso

Ravenswood

Content available here

USGS Publications

Social attraction used to establish Caspian tern (Hydroprogne caspia) nesting colonies on modified islands at the Don Edwards San Francisco Bay National Wildlife Refuge, California—Final report

Biruk — Fri, 01 Nov 2019 19:11:45 +0000

Social attraction used to establish Caspian tern (Hydroprogne caspia) nesting colonies on modified islands at the Don Edwards San Francisco Bay National Wildlife Refuge, California—Final report Biruk Fri, 11/01/2019 - 12:11

Document Category

Scientific Reports

Author(s)

Date

2018

Summary

Executive Summary
To address the 2008/2010 and Supplemental 2014 National Oceanic and Atmospheric
Administration Fisheries Biological Opinion for operation of the Federal Columbia River Power
System, the U.S. Army Corps of Engineers (USACE) and the Bureau of Reclamation (Reclamation)
developed and began implementation of Caspian tern (Hydroprogne caspia) management plans. This
implementation includes redistribution of the Caspian terns in the Columbia River estuary and the mid-
Columbia River region to reduce predation on salmonids listed under the Endangered Species Act. Key
elements of the plans are (1) reduction of nesting habitat for Caspian terns in the Columbia River estuary
and the mid-Columbia River region, and (2) creation or modification of nesting habitat at alternative
sites within the Caspian tern breeding range. As part of this effort, USACE and Reclamation developed
Caspian tern nesting habitat at the U.S. Fish and Wildlife Service Don Edwards San Francisco Bay
National Wildlife Refuge (DENWR), California, prior to the 2015 nesting season. Furthermore, nesting
habitat for western snowy plovers (Charadrius alexandrinus nivosus) also was developed to provide
separate nesting opportunities in the same managed ponds to reduce potential conflicts with Caspian
terns. Specifically, seven recently constructed islands within two managed ponds (Ponds A16 and SF2)
of DENWR were modified to provide habitat attractive to nesting Caspian terns (5 islands) and snowy
plovers (2 islands). These 7 islands were a subset of 46 islands recently constructed in Ponds A16 and
SF2 to provide waterbird nesting habitat as part of the South Bay Salt Pond (SBSP) Restoration Project.

We used social attraction methods (decoys and electronic call systems) to attract Caspian terns
and snowy plovers to these seven modified islands, and conducted surveys from March to September of
2015, 2016, and 2017 to evaluate nest numbers, nest density, and productivity. Results from the 2015
nesting season, the first year of the study, indicated that island modifications and social attraction
measures were successful in establishing Caspian tern breeding colonies at Ponds A16 and SF2 of
DENWR. Prior to 2015, there was no history of Caspian terns nesting in either Pond A16 or Pond SF2.
The success of 2015 continued in 2016 and 2017. In 2017, the third and final year of the project,
Caspian terns initiated at least 664 nests, fledged at least 239 chicks, and had a breeding success rate of
0.36 fledged chicks per breeding pair. This represents a 171 percent increase in the number of breeding
pairs and a 41 percent increase in the number of chicks fledged, but a 48 percent decrease in the
fledglings produced per breeding pair in 2017 compared to 2015, the first year the colonies were
established. The two new large and growing Caspian tern nesting colonies at Ponds A16 and SF2
demonstrate the effectiveness of social attraction measures in helping to establish tern nesting colonies
in San Francisco Bay. Social attraction measures similar to those used in this study, but targeting other
colonial species such as Forster’s terns (Sterna forsteri) and American avocets (Recurvirostra
americana), may help to establish waterbird breeding colonies at wetlands enhanced as part of the SBSP
Restoration Project.

Keywords

Pond Complex

Alviso

Ravenswood

Content available here

https://pubs.usgs.gov/of/2018/1136/ofr20181136.pdf

The Critical Role of Islands for Waterbird Breeding and Foraging Habitat in Managed Ponds of the South Bay Salt Pond Restoration Project, South San Francisco Bay, California

admin — Thu, 23 Nov 2017 00:21:53 +0000

The Critical Role of Islands for Waterbird Breeding and Foraging Habitat in Managed Ponds of the South Bay Salt Pond Restoration Project, South San Francisco Bay, California admin Wed, 11/22/2017 - 16:21

Document Category

Scientific Reports

Author(s)

Susan E. W. De la Cruz

Julie L. Yee

John Y. Takekawa

Date

2014-12-31

Summary

The South Bay Salt Pond Restoration Project aims to restore 50–90 percent of former salt evaporation ponds into tidal marsh in South San Francisco Bay, California. However, large numbers of waterbirds use these ponds annually as nesting and foraging habitat. Islands within ponds are particularly important habitat for nesting, foraging, and roosting waterbirds. To maintain current waterbird populations, the South Bay Salt Pond Restoration Project plans to create new islands within former salt ponds in South San Francisco Bay. In a series of studies, we investigated pond and individual island attributes that are most beneficial to nesting, foraging, and roosting waterbirds.

Keywords

Effects of Human Disturbance on Waterbird Nesting Effort and Reproductive Success at Restoration Pond SF2, South San Francisco Bay, California

admin — Thu, 23 Nov 2017 00:21:53 +0000

Effects of Human Disturbance on Waterbird Nesting Effort and Reproductive Success at Restoration Pond SF2, South San Francisco Bay, California admin Wed, 11/22/2017 - 16:21

Document Category

Scientific Reports

Author(s)

Joshua T. Ackerman

Mark P. Herzog

C. Alex Hartman

Date

2014-11-1

Summary

To offset for the loss of managed pond habitat during restoration of wetlands to tidal marsh, the South Bay Salt Pond Restoration Project is enhancing some of the remaining ponds by constructing islands for roosting and nesting waterbirds. Among these wetland habitats, the SBSP Restoration Project also is installing walking trails and viewing platforms in an effort to bring the public closer to nature. In winter of 2010–11, the SBSP Restoration Project constructed 30 islands in Pond SF2 and walking trails and viewing platforms around the edge of the pond. The restoration project partners acknowledged that human disturbance could detrimentally affect nesting and roosting waterbirds. Although optimal buffer distances and potential for human disturbance were unknown, islands in Pond SF2, nevertheless, were designed with built-in buffers of greater than 300 feet (91 meters) from a trail and 600 feet (182 meters) from a viewing platform in order to minimize potential human disturbances.

To determine the effects that human disturbance may have on waterbirds nesting on these newly constructed islands in Pond SF2, we assessed the potential effects of human disturbance features (specifically, access trails, viewing platforms, internal pond berms, exterior levees, and highways) on breeding waterbirds in 2011 and 2012. We found no clear pattern of potential disturbance features on a group of reproductive factors, including nest survival, nest initiation date, and clutch size. Because all the islands were constructed greater than 90 meters from the nearest disturbance feature, Pond SF2 alone did not provide adequate variation in the distance of disturbance features to detect potential detrimental effects for islands closer to disturbance features in other areas of the SBSP Restoration Project. If there is a need for SBSP Restoration Project Management Team to understand how close islands can be built to disturbance features in the future, we suggest a more comprehensive study that includes multiple ponds, other than SF2, with islands at varying distances to disturbance features.

Open-File Report 2014–1223

/documents/technical/Ackerman%20etal%202014%20Waterbird%20Nest%20Disturbance%20OFR_2014-1223.pdf

Keywords

birds

waterbirds

trail use/public access

nesting islands

Pond Complex