UCSB SONGS Mitigation Monitoring Methods Last Modified: 2020-12-04

SONGS Mitigation Monitoring: Wetland Performance Standard – Food Chain Support

Overview The coastal development permit for SONGS Units 2 and 3 requires Southern California Edison to create or substantially restore a minimum of 150 acres of coastal wetland. The permit establishes biological performance standards that must be met by the restored wetland. One of these standards requires that within 4 years of construction, the food chain support (FCS) provided to shall be similar to that provided by the reference sites, as determined by feeding activity of the birds. Feeding activity is evaluated using the density of feeding birds.

Study Sites Time series data of abundance and feeding activity were collected from twenty 100 m x 150 m plots at the San Dieguito Wetland restoration site (32.9695450N, 117.260470W) and three reference wetlands (Tijuana Estuary 32.5699010N, 117.1267120W; Mugu Lagoon 34.1020070N, 119.0970110W; Carpinteria Salt Marsh 34.4011890N, 119.5379900W) as part of a long-term study designed to evaluate the performance of the restoration project. The reference wetlands were chosen to represent relatively undisturbed, natural tidal wetlands within the Southern California Bight. At each wetland, birds were surveyed six times annually. Surveys were performed during two separate months in each of three seasons: winter (January, February), spring (April, May), and fall (October, November). Each plot is sampled three times during a survey, on three consecutive days.

Target Species Food chain support was estimated for twelve shorebird species common in all of the study wetlands. Observations were limited to birds found on the ground in each plot. The target species are listed in the following table:

Common Name Scientific Name American Avocet Recurvirostra americana Black-bellied Plover Pluvialis squatarola Black-necked Stilt Himantopus mexicanus Dunlin alpina Limnodramus spp. Greater Yellowlegs flavipes Long-billed Numenius americanus Killdeer Charadrius vociferus Marbled Limosa fedoa Semi-palmated Plover Charadrius semipalmatus Willet Tringa semipalmata Whimbrel Numenius phaeopus

Density of Feeding Birds

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UCSB SONGS Mitigation Monitoring Methods Last Modified: 2020-12-04

The density of feeding birds in each plot was calculated by combining estimates of bird abundance with estimates of bird feeding activity. The methods for these surveys can be found in the following data packages:

SONGS Mitigation Monitoring: Wetland Survey - Bird Abundance SONGS Mitigation Monitoring: Wetland Survey - Bird Feeding Activity

The number of each target species observed feeding in a given plot during 30 minutes of observation on a given date was calculated as the product of the total number of individuals of that species counted on the ground, and the proportion of them observed feeding). The density of feeding birds for all species combined in the plot was calculated as the sum of the number of feeding birds of all species divided the area of the plot. The number of birds feeding in a given plot during a 30 minute period for each of the sampling date of that year were averaged to produce an annual mean number of birds feeding in that plot.

Food Chain Support (FCS) Because bird feeding is evaluated for shorebirds on the ground, the sample size (number of plots) evaluated for bird feeding varied among wetlands depending on the number of plots having birds present. To ensure that each wetland was weighted equally, the density of feeding birds for a given year was resampled with replacement 20 times (20 being the targeted sample size). This process was iterated 1000 times, and the mean for each iteration was calculated to produce a dataset of 1000 replicate FCS values for each wetland for a given year.

The four-year running median of the FCS vales for each wetland was calculated using a four- year mean of each iteration based on the current year and previous three years producing 1000 values of the four-year average of the FCS values for each wetland. The four-year median and standard deviation of the FCS values used to evaluate each wetland’s performance with respect to FCS was calculated from the resampled distribution of these 1000 values.

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