EXECUTIVE SUMMARY
The South Bay Salt Pond Restoration Project (SBSPRP) is restoring over 15,000 acres of former
salt evaporation ponds to a mix of tidal marsh and ponded wetland habitats. These wetlands
provide habitat for many waterbirds, including migrating red-necked phalarope (Phalaropus
lobatus) and Wilson’s phalarope (P. tricolor). Sustaining baseline population goals for wildlife
populations requires understanding how species are responding to restoration actions over time.
As part of the Project’s Adaptive Management Plan, NEPA/CEQA baseline population levels
were calculated based on Salt Pond Survey data from 2005–2007, before major restoration
efforts began. If a species group is observed to drop below a sustained threshold or hit a
single-year trigger point below that baseline, the Project is committed to evaluating available
data and considering targeted management action. In 2017, phalarope counts were 78% below
the baseline value, which is well beyond the action trigger of 50% below the baseline of a
monthly summer average of 3225 birds.

In response to this observed decline, targeted Phalarope Migration Surveys were piloted in 2019
and have been implemented in 2020–2022 with the goal of better capturing phalarope counts
during their brief migration window through the Bay Area and the salt ponds. As these new
surveys and the Salt Pond Surveys use different protocols with different levels of detectability, it
would be misleading to simply compare raw Phalarope Migration Survey results to the baseline.
The goal of this report was to identify data analysis strategies that could best assess the new
phalarope migration survey data with respect to the original NEPA/CEQA baseline.

We calculated adjustments to both the Phalarope Migration Survey data and the original baseline
to control for differences in survey location, timing, and frequency. In situations where there
were multiple options for how to reconcile these differences, we performed each alternative.

The results demonstrate that in every case, the counts from 2020–2022 are more than 50% below
the NEPA/CEQA baseline, hitting the management trigger. For future comparisons, we
recommend using a revised baseline that includes September surveys to more closely align with
the new Phalarope Migration Survey protocol. We also recommend continued Phalarope
Migration Surveys until there are sufficient years of survey data to perform an advanced analysis
of the rate of population change and differences between the restoration sites and those external
to the Project area. At a minimum this requires at least one more year of Phalarope Migration
Surveys, to give us a total of three complete years, but the quality of results will improve with
further years. Additionally, surveys should be conducted before and after major changes to pond
state (e.g., drying or breaching) in order to understand the impact of restoration activities.

Date
2023-04
Associated File(s)
Download Document PDF - bridging_phalarope_survey_data_report_final.pdf (1.15 MB)