Geology topics

Research about Don Edwards San Francisco Bay National Wildlife Refuge

Source-linked reports with geographic coverage including Don Edwards San Francisco Bay National Wildlife Refuge.

5 recordsLinked to original sources

USGS2018

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

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.

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USGS2018

Evaluation of social attraction measures to establish Forster’s tern (Sterna forsteri) nesting colonies for the South Bay Salt Pond Restoration Project, San Francisco Bay, California—2017 Annual Report

Forster’s terns ( Sterna forsteri ), historically one of the most numerous colonial-breeding waterbirds in South San Francisco Bay, California, have had recent decreases in the number of nesting colonies and overall breeding population size. The South Bay Salt Pond (SBSP) Restoration Project aims to restore 50–90 percent of former salt evaporation ponds to tidal marsh habitat in South San Francisco Bay. This restoration will remove much of the historical island nesting habitat used by Forster’s terns, American avocets ( Recurvirostra americana ), and other waterbirds. To address this issue, the SBSP Restoration Project organized the construction of new nesting islands in managed ponds that will not be restored to tidal marsh, thereby providing enduring island nesting habitat for waterbirds. In 2012, 16 new islands were constructed in Pond A16 in the Alviso complex of the Don Edwards San Francisco Bay National Wildlife Refuge, increasing the number of islands in this pond from 4 to 20. However, despite a history of nesting on the four historical islands in Pond A16 before 2012, no Forster’s terns have nested in Pond A16 since the new islands were constructed. In 2017, we used social attraction measures (decoys and electronic call systems) to attract Forster’s terns to islands within Pond A16 to re-establish nesting colonies. We maintained these systems from March through August 2017. To evaluate the effect of these social attraction measures, we also completed waterbird surveys between April and August, where we recorded the number and location of all Forster’s terns and other waterbirds using Pond A16, and monitored waterbird nests. We compared bird survey and nest monitoring data collected in 2017 to data collected in 2015 and 2016, prior to the implementation of social attraction measures, allowing for direct evaluation of social attraction efforts on Forster’s terns. To increase the visibility and stakeholder involvement of this project, we engaged in multiple outreach activities, including the development of a project web site ( https://apps.usgs.gov/shorebirds/ ) and educational video ( https://www.youtube.com/watch?v=-IaZD0YlAvM&feature=youtu.be ); publication of a popular article ( http://www.sfestuary.org/estuary-news-caspian-push-and-pull/ ); and public presentations to relay findings to managers, stakeholders, and the general public. The relative number of Forster’s terns using Pond A16, after adjusting for the overall South San Francisco Bay breeding population each year, was higher during the nesting period in 2017 (after social attraction was used) than in 2015 and 2016 (before social attraction was used). Furthermore, in 2017, more Forster’s terns were observed in the areas of Pond A16 where decoys and call systems were deployed during the pre-nesting and nesting periods. Although no Forster’s tern nests were recorded in Pond A16 before (2015, 2016) or after (2017) implementation of social attraction measures, bird survey results indicate that Forster’s terns were attracted to areas within Pond A16 where decoys and call systems were deployed, suggesting that terns may have been prospecting for future breeding sites. As social attraction efforts often benefit from multiple years of decoy and call system deployment, these first-year results suggest that continued implementation of social attraction measures could help to re-establish Forster’s tern breeding colonies in Pond A16 and other areas of South San Francisco Bay.

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USGS2017

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

Executive Summary In order to address the 2008/10 and Supplemental 2014 NOAA 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 have begun 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 include (1) reducing nesting habitat for Caspian terns in the Columbia River estuary and the mid-Columbia River region, and (2) creating or modifying nesting habitat at alternative sites within the Caspian tern breeding range. 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, to reduce or eliminate potential conflicts between nesting Caspian terns and threatened western snowy plovers ( Charadrius alexandrinus nivosus), nesting habitat for snowy plovers also was developed. 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 between March and September of 2015 and 2016 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. The success of 2015 continued in 2016, the second year of the study. In 2016, Caspian terns nested on two of the five islands modified for Caspian terns (one island in Pond A16 and one island in Pond SF2). Caspian terns initiated at least 317 nests, fledged at least 158 chicks, and had a breeding success rate of 0.50 fledged chicks per breeding pair. This represents a 42 percent increase in nests initiated, a 9 percent decrease in the number of fledged chicks, and a 36 percent decrease in the number of chicks fledged per breeding pair in 2016 compared to 2015. Although overall productivity decreased from 2015, these results indicate that the Caspian tern breeding population on modified islands of the DENWR is increasing relative to 2015, the first year of the effort, and relative to years prior to 2015 when no breeding colonies of Caspian terns existed in Ponds A16 or SF2. These results indicate the effectiveness of social attraction measures in helping to establish tern nesting colonies in San Francisco Bay. Conversely, for the second year in a row, snowy plovers did not attempt to nest on any island in Ponds A16 and SF2. 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.

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USGS2016

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

Executive Summary In order to address the 2008/10 NOAA 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) have developed and begun implementation of Caspian tern ( Hydroprogne caspia ) management plans. This implementation includes relocating nesting Caspian terns out of the Columbia River estuary and the mid-Columbia River region to reduce predation on salmonids listed under the Endangered Species Act. 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. Further, to reduce or eliminate potential conflicts between nesting Caspian terns and threatened western snowy plovers ( Charadrius alexandrinus nivosus), nesting habitat for snowy plovers also was developed. 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 seven 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 between March and September 2015 to evaluate nest numbers, nest density, and productivity. Results from the 2015 nesting season indicate that island modifications and social attraction measures were successful in establishing Caspian tern breeding colonies at Ponds A16 and SF2 of DENWR. Caspian terns nested on three of the five islands modified for Caspian terns (1 island in Pond A16 and 2 islands in Pond SF2). Caspian terns initiated at least 224 nests, fledged at least 174 chicks, and exhibited a breeding success rate of 0.78 fledged chicks/breeding pair. These results are promising considering it was the first year of the study and there was no prior history of Caspian terns nesting at Ponds A16 and SF2. In contrast, snowy plovers did not attempt to nest on any island in Ponds A16 and SF2. These results demonstrate the potential of social attraction measures to help establish tern nesting colonies in San Francisco Bay. Social attraction measures similar to those used in this study, but targeting other species such as Forster’s terns and American avocets, may help to establish waterbird breeding colonies at wetlands enhanced as part of the SBSP Restoration Project.

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USGS2011

Identifying nest predators of American avocets (Recurvirostra americana) and black-necked stilts (Himantopus mexicanus) in San Francisco Bay, California

We evaluated predation on nests and methods to detect predators using a combination of infrared cameras and plasticine eggs at nests of American avocets ( Recurvirostra americana ) and black-necked stilts ( Himantopus mexicanus ) in Don Edwards San Francisco Bay National Wildlife Refuge, San Mateo and Santa Clara counties, California. Each technique indicated that predation was prevalent; 59% of monitored nests were depredated. Most identifiable predation ( n = 49) was caused by mammals (71%) and rates of predation were similar on avocets and stilts. Raccoons ( Procyon lotor ) and striped skunks ( Mephitis mephitis ) each accounted for 16% of predations, whereas gray foxes ( U rocyon cinereoargenteus ) and avian predators each accounted for 14%. Mammalian predation was mainly nocturnal (mean time, 0051 h ± 5 h 36 min), whereas most avian predation was in late afternoon (mean time, 1800 h ± 1 h 26 min). Nests with cameras and plasticine eggs were 1.6 times more likely to be predated than nests where only cameras were used in monitoring. Cameras were associated with lower abandonment of nests and provided definitive identification of predators.

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