Josh Scullen

Western Snowy Plover and California Least Tern Monitoring in the San Francisco Bay Annual Report 2023

ariela — Sat, 27 Jan 2024 00:03:59 +0000

Western Snowy Plover and California Least Tern Monitoring in the San Francisco Bay Annual Report 2023

Three snowy plover chicks

ariela Fri, 01/26/2024 - 16:03

Document Category

Scientific Reports

Author(s)

Date

2024-01

Summary

Excerpts from Executive Summary

During the 2023 breeding season, SFBBO monitored Snowy Plover population size, nesting and fledging success, the use of experimental habitat enhancement sites, and potential predators at eight historical salt production pond complexes in the South San Francisco Bay.

During the Pacific Coast rangewide winter window survey (January 26 – 30, 2023) SFBBO and other organizations counted a total of 262 adult Snowy Plovers within RU3, while during the breeding season window survey (May 20 – 27, 2023), SFBBO and other organizations counted a total of 368 adult Snowy Plovers within RU3. Over the course of the breeding season (March – September), SFBBO staff determined and documented the fates of 304 Snowy Plover nests in the South San Francisco Bay. Of the 304 nests monitored by SFBBO, 64% hatched, 31% were depredated, 2% were flooded, 1% fell to miscellaneous other fates and 2% were unknown. An additional 39 nests were detected at the brood stage.

Other members of RU3 documented a total of 23 nests. Among these 23 nests, 43% hatched, 35% were depredated, 13% fell to miscellaneous other fates, and 9% were unknown. An additional eight nests were documented at the brood stage.

SFBBO banded 194 Snowy Plover chicks from nests that successfully hatched within Alviso, Dumbarton, ELER, Ravenswood, and Warm Springs nesting ponds, representing 38 percent of all chicks known to have hatched from SFBBO monitored sites in the South Bay. From band re-sighting surveys and reports from other scientists and birders across the species’ range, we determined that at least 64 of these chicks survived to fledge (fully flight capable, at least 28 days post-hatching) as of December 12, 2023, resulting in an estimated apparent fledging success of 33 percent. Due to concerns regarding highly pathogenic avian influenza (HPAI), we limited our adult banding efforts. We recaptured and re-banded three adults whose bands had been damaged. Comparing adult band re-sighting and fledged juvenile data from 2022, we found return rates of 58% (n=63) for adults banded in or before 2022 and 60% (n=62) for 2022 fledges.

During avian predator surveys, we counted California Gulls (Larus californicus) and unidentified gulls (Larus spp.; likely California Gulls due to the time of year and locations) as the most numerous potential avian predators in Snowy Plover nesting areas. Common Ravens (Corvus corax), American Crows (Corvus brachyrhynchos), Snowy Egrets (Egretta thula), and Great Egrets (Ardea alba) were the next most commonly observed predator species. Two avian species and one mammalian species were confirmed as predators of Snowy Plovers in 2023 due to the following observations: a Northern Harrier depredating an incubating female Snowy Plover at A12, as reported by HT Harvey and Associates; a California Gull depredating a Snowy Plover chick at PP1; and red fox scat with Snowy Plover color bands embedded in it at E14.

We continued to monitor Snowy Plover use of oyster shell plots, which were spread in September 2014 in two areas of ELER pond E14 (Western = 6.47 ha; Eastern = 13.76 ha) as a large scale habitat enhancement project. We monitored 39 Snowy Plover nests in E14 and found an additional three nests at the brood stage; at least 24 nests were found within one of the shell plots. Chi-square analyses indicated that based upon available habitat, breeding Snowy Plovers preferred to nest in shelled plots. Nest survival analyses found the daily nest survival (DSR) to be 98.3% with a 60.9% chance that a nest would survive to hatch (33 days).

2023 marked the seventh consecutive year that California Least Terns (Sternula antillarum browni; Least Terns) nested at pond E14. This year Least Terns also nested on the levee between ponds E12 and E13, on a constructed island on E13, and for the first time on pond E6B. On March 4, 2023, we led a volunteer event to remove encroaching vegetation, spread oyster shells, and place 15 wooden chick shelters within the Western Shell Plot of E14. Least Terns were first observed at ELER on May 2, when an unknown number of adults were heard flying over E14. The maximum number of adults recorded on-site was 55 on July 11. A total of 77 nests were monitored between ponds E6B, E12, E13, and E14. In E14, a total of 22 nests were monitored, with two confirmed to have hatched. Eighteen failed (did not hatch due to depredation, abandonment, or flooded out), and the fate of two nests could not be determined. No fledglings were produced from E14. At E12 and E13, a total of 25 nests were monitored, with three confirmed to have hatched and three more presumed to have hatched. Sixteen nests failed and the fate of three nests could not be determined. Between three and four fledglings are estimated to have been produced from E13. At E6B, a total of 30 nests were monitored, with seven confirmed to have hatched and an additional eight presumed to have hatched. The other 15 nests failed. Based on scat and prints, SFBBO suspects that red foxes depredated the majority of the Least Tern nests in ELER.

In 2023, SFBBO continued to interface with the various land and project managers throughout the South Bay, including the South Bay Salt Pond Restoration Project (SBSPRP), whose actions are reshaping the Bay’s ecosystems and seriously impacting Snowy Plovers and Least Terns. During Phase 1 of the SBSPRP, restoration and reconfiguration of ponds that formerly supported Snowy Plover breeding habitat resulted in the loss of roughly 19% of available breeding habitat for Snowy Plovers. To account for the decline in available habitat, new water control structures were installed in many ponds at Don Edwards SFBNWR and ELER to allow for better management of habitat. In 2022 and 2023 respectively, we recorded the second highest (288) and highest (368) breeding population sizes ever recorded in RU3, suggesting a growing population size. However, since 2020, the proportion of breeding adult Snowy Plovers found on SBSPRP lands compared to all of RU3 has consistently been under 80 percent, when the lowest it had previously dropped between 2003 and 2019 was 83 percent in 2018. Some of this lower ratio can be attributed to expanded survey efforts across RU3, but the recent movement of Snowy Plovers away from high density nesting at E14, and instead diversifying to sites across RU3 is also relevant. In order to reach the SBSPRP and RU3 goals of 250 and 500 breeding birds, respectively, it will likely be necessary to provide multiple enhanced breeding ponds, both locally and throughout RU3, in conjunction with targeted predator control efforts to reduce predation pressure on any one pond.

Phase 2 restoration on Refuge lands includes restoration activities at the Ravenswood Complex (R3, R4, R5/S5), Alviso Complex (A8 Ponds: A8, Mountain View Ponds: A1, A2W and the Island Ponds: A19, A20). Pond R3 has been enhanced for Snowy Plovers by adding water management capabilities with the addition of a new water control structure. However, overall Phase 2 actions at the Refuge have still resulted in an additional 8% loss of remaining available breeding habitat due to the breaching of R4 in December 2023. It will be critical to enhance remaining Snowy Plover breeding habitat at R1 through R3 and SF2 to account for the higher density of breeding that will likely occur in these areas. Reduced habitat availability could result in increased predation pressure at the Ravenswood Complex. Furthermore, increased development adjacent to these restoration sites artificially inflates human commensal predator populations such as skunks, feral cats, American Crows, and Common Ravens by supplementing food and complicating predator management opportunities in locations with high visitor use. Without additional enhancement and informed predator control efforts, population growth at one of the most important breeding sites in RU3 could be impeded.

Currently, most breeding plovers in RU3 are found in the South Bay, and a large proportion of those plovers breed on SBSPRP lands. We recommend that the SBSPRP plan Phase 2 construction activities to avoid negatively impacting breeding Snowy Plovers, as was done in Phase 1. This includes providing alternative breeding habitats when construction activities impact or eliminate Snowy Plover nesting ponds and scheduling construction activities before or after the Snowy Plover breeding season when possible.

The recovery of the RU3 plover population depends on the continued availability of suitable habitats, which are currently owned and managed by multiple landowners. Providing quality habitat at spatially diverse locations throughout RU3 is a critical strategy to prevent population decline caused by overconcentration of breeding in any one area. Our research over the past nine years at E14 highlights that “placing all the eggs in one basket” is not an effective long-term strategy for meeting recovery goals. Adaptive management strategies on SBSPRP land to balance tidal restoration with Snowy Plover needs, despite the increased cost of managing ponds and future concerns about sea level rise adaptation, could serve as a positive example for other landowners. Aside from the SBSPRP, other RU3 landowners have not adequately accounted for Snowy Plovers when making land management and restoration decisions, particularly in the North Bay where Snowy Plovers were long known to breed in former salt production ponds but have been left with minimal nesting habitat following widespread tidal marsh restoration. Management actions by the SBSPRP to balance tidal marsh and pond dependent species should be continued in future seasons, including management of multiple ponds with a mixture of exposed pond and shallow water depth during the winter and the implementation of large scale shell, gravel, and/or cobble enhancement to attract Snowy Plovers to appropriate nesting ponds.

Thus we recommend that Refuge biologists and USFWS Snowy Plover Recovery Leads continue to promote enhancement, management, and maintenance of Snowy Plover habitat on SBSPRP land, and encourage the Bay Delta Fish and Wildlife Office and landowners to increase efforts to identify suitable habitat in the rest of RU3 that can be enhanced or managed for breeding Snowy Plovers and maintain existing Snowy Plover habitat when feasible as outlined in the Recovery Plan (USFWS 2007). In addition, we recommend that all managers communicate and coordinate tidal marsh restoration activities to ensure that adequate Snowy Plover breeding habitat will remain to support recovery throughout RU3.

Keywords

Cargill Salt Pond Waterbird Surveys Report, October 2008 - September 2009

admin — Tue, 14 Nov 2023 21:39:08 +0000

Cargill Salt Pond Waterbird Surveys Report, October 2008 - September 2009 admin Tue, 11/14/2023 - 13:39

Document Category

Monitoring Reports

Author(s)

Caitlin W. Robinson-Nilsen

Jill D. Bluso-Demers

Josh Scullen

Date

2009-12-01

Summary

The San Francisco Bay Bird Observatory surveyed 22 salt evaporation ponds for waterbirds and sampled water quality from October 2008 through September 2009. The salt ponds surveyed are owned by the Don Edwards San Francisco Bay National Wildlife Refuge and managed for salt production by Cargill Salt. We examined species richness, total abundance within and between complexes. We also examined the difference in abundance of foraging guilds within each complex.

We observed 421,939 birds during our monthly surveys between October 2008 and September 2009. Species richness was greatest in Coyote Hills and Mowry complexes and lowest in the Dumbarton complex. Total abundance was highest in the Mowry complex, followed by Coyote Hills, then Dumbarton. The proportion of birds foraging was greatest in Coyote Hills and Dumbarton complexes, whereas birds mostly roosted in the Mowry complex.

We found that guilds were most abundant in specific ponds and water quality parameters often dictated guild-specific distributions. These distributions were likely driven by the prey distribution and the conditions needed for their survival. For example, we rarely found fish eaters in high salinity ponds because fish species cannot tolerate those salinities. Likewise, we often observed Eared Grebes, phalaropes, and shorebirds in high salinity ponds where brine shrimp and flies are likely abundant. Shorebird abundance is also dependent upon appropriate water depth for foraging and islands for roosting.

As the South Bay Salt Pond Restoration Project progresses, we recommend management of salt pond habitats to retain bird populations by maintaining a variety of water salinities for the guilds. Special consideration should be given to birds that prefer medium to high salinity ponds such as phalaropes and Eared Grebes. We also suggest providing lower water levels in some ponds for small and medium shorebirds during migration, and creating or maintaining islands or undisturbed levees for shorebird roosting habitat. Finally, as the restoration progresses, continuing to monitor avian use of these ponds will allow for managers to assess the success of the restoration in maintaining current bird populations.

Pond Complex

Alviso

Ravenswood

Content available here

Cargill Salt Pond Waterbird Surveys Report, October 2008 - September 2009

Salt Pond Waterbird Surveys Data Summary October 2011 - September 2012

Dave Halsing — Tue, 26 Apr 2022 18:37:19 +0000

Salt Pond Waterbird Surveys Data Summary October 2011 - September 2012 Dave Halsing Tue, 04/26/2022 - 11:37

Document Category

Scientific Reports

Author(s)

Date

2013-01

Summary

This report conveys the results of the 2012 nesting waterbird monitoring program, led by the San Francisco Bay Bird Observatory.

Keywords

Pond Complex

Alviso

Eden Landing

Ravenswood

Western Snowy Plover Monitoring in the San Francisco Bay Annual Report 2015

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

Western Snowy Plover Monitoring in the San Francisco Bay Annual Report 2015 admin Wed, 11/22/2017 - 16:21

Document Category

Progress Reports

Author(s)

Ben Pearl

Karine Tokatlian

Josh Scullen

Date

2016-02-17

Summary

The San Francisco Bay Bird Observatory (SFBBO), Don Edwards San Francisco Bay National Wildlife Refuge (Refuge), California Department of Fish and Wildlife (CDFW), Hayward Area Recreation and Park District (HARD), and East Bay Regional Park District (EBRPD) form the Western Snowy Plover (Charadrius nivosus nivosus) Recovery Unit 3. The goal of this collaboration is to survey managed ponds and other habitats for Western Snowy Plovers, track breeding success, and contribute to the management and recovery of this species in the San Francisco Bay. During the 2015 breeding season, we monitored Snowy Plover numbers, nesting and fledging success, use of experimental habitat enhancement sites, and potential predators. We also participated in the second year of a reproductive success pilot study initiated by the Institute for Wildlife Studies (IWS).

Keywords

snowy plover

Oyster Shell Habitat Enhancement for Breeding Snowy Plovers in Pond E14, Eden Landing Ecological Reserve, 2015

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

Oyster Shell Habitat Enhancement for Breeding Snowy Plovers in Pond E14, Eden Landing Ecological Reserve, 2015 admin Wed, 11/22/2017 - 16:21

Document Category

Scientific Reports

Author(s)

Date

2016-02-01

Summary

From 2008 to 2014, SFBBO conducted a pilot study investigating the effects of oyster shell habitat enhancement on Snowy Plover nesting success. One hectare test plots were distributed on salt pond bottoms in Eden Landing Ecological Reserve (Eden Landing), Hayward, California. Data from this pilot study indicated that oyster shells may provide beneficial cover for nesting Snowy Plovers and suggest further breeding benefits on a larger scale. In October 2014 and through funding from Ducks Unlimited, two large oyster shell enhancement plots were distributed in pond E14, Eden Landing; non-shelled areas acted as controls. During the 2015 breeding season, SFBBO monitored Snowy Plover adults, nests, chicks, predatory species and activity, and biotic and abiotic soil characteristics of all areas within E14.

Keywords

Western Snowy Plover Monitoring in the San Francisco Bay Annual Report 2014

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

Western Snowy Plover Monitoring in the San Francisco Bay Annual Report 2014 admin Wed, 11/22/2017 - 16:21

Document Category

Progress Reports

Author(s)

Karine Tokatlian

Josh Scullen

Catherine Burns

Date

2014-12-31

Summary

Keywords

monitoring

western snowy plover

birds

Managed Pond Waterbird Surveys September 2013 - August 2014

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

Managed Pond Waterbird Surveys September 2013 - August 2014 admin Wed, 11/22/2017 - 16:21

Document Category

Scientific Reports

Author(s)

Date

2015-06-17

Summary

This report serves as a data summary and coarse-scale assessment of waterbird and water quality monitoring efforts at Alviso, Eden Landing, Coyote Hills, Dumbarton, Mowry and Ravenswood pond complexes in the South San Francisco Bay. Coyote Hills, Dumbarton and Mowry salt ponds are owned by Don Edwards San Francisco Bay National Wildlife Refuge and managed for salt production by Cargill Salt. Alviso and Ravenswood complexes are owned and managed by Don Edwards San Francisco Bay National Wildlife Refuge; Eden Landing ponds are owned and managed by California Department of Fish and Wildlife. This report is based on data collected by the San Francisco Bay Bird Observatory between September 2013 and August 2014, although previous years’ data are also included in several areas.

Keywords

birds

survey

wildlife

Establishing baseline conditions to inform adaptive management of South San Francisco Bay salt ponds: A comparison of waterbird abundance from the 1980s to the 2000s

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

Establishing baseline conditions to inform adaptive management of South San Francisco Bay salt ponds: A comparison of waterbird abundance from the 1980s to the 2000s admin Wed, 11/22/2017 - 16:21

Document Category

Scientific Reports

Author(s)

Date

2013-10-16

Summary

The 30,000 acres of wetlands within the Don Edwards San Francisco Bay National Wildlife Refuge (Refuge) provide critical habitat for over one million waterbirds annually (Page et al. 1999, Warnock et al. 2002). These wetlands consist largely of tidal marshes and open water ponds. Salt evaporator ponds have been in this landscape for over 150 years (Ver Planck 1958) and are heavily used by shorebirds, waterfowl and other wildlife species (Anderson 1970, Accurso 1992, Takekawa et al. 2001, Warnock et al. 2002). Salt ponds, and former salt ponds now managed as wildlife habitat, provide the majority of the roosting and (for some species) foraging habitat for waterbirds in the San Francisco Bay. The South Bay Salt Pond Restoration Project (Restoration Project), of which the Refuge and California Department of Fish and Wildlife’s (CDFW, also CDFG) Eden Landing Ecological Reserve are a part, is implementing a large-scale plan to convert 15,100 acres of former salt ponds into tidal and managed wetland habitats (SBSPRP 2007)

Keywords

habitat restoration

tidal marshes

birds

Salt Pond Waterbird Surveys Data Summary October 2011 - September 2012

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

Salt Pond Waterbird Surveys Data Summary October 2011 - September 2012 admin Wed, 11/22/2017 - 16:21

Document Category

Scientific Reports

Author(s)

Date

2012-09-01

Summary

This report serves as a data summary and preliminary, coarse-scale assessment of waterbird and water quality monitoring efforts at Coyote Hills, Dumbarton, and Mowry salt pond complexes in the South San Francisco Bay.

Keywords

birds

endangered species