<strong>Bolsa</strong> <strong>Chica</strong> <strong>Lowlands</strong> Restoration <strong>Monitoring</strong><strong>2007</strong> <strong>Annual</strong> <strong>Report</strong>Each of five teams, which included 2-3 people (1-2 observers and 1 recorder), was responsible forsurveying an assigned set of zones over each survey day, which extended from approximately 0700 to1200. Team size depended upon complexity of the survey area and general abundance of birds.Multiple observers allowed teams to survey multiple zones at the same time and minimize over-countsassociated with bird movements.The field biologists used both binoculars and spotting scopes to identify and count species. All teamsconducted surveys simultaneously. Data collected included species, number of individuals, activities ofthe birds (foraging, flying, resting, or showing evidence of breeding), and habitats in which the birdsoccurred (open water, nesting site, mud flat, salt marsh, disturbed salt marsh, freshwater marsh, willowriparian, baccharis scrub, salt panne [dry], inundated salt panne, and non-native vegetation). Weatherconditions, including air temperature, wind speed, wind direction, cloud cover, precipitation, and tideheight, were recorded several times during each survey day.Due to the large size of the zones being surveyed, particularly in the FTB, identifications were oftenmade over great distances. When it was not possible to identify a bird to species, due to distance,overhead flight, or a limited view of the bird, a less specific identification was made such asunidentified gull or unidentified swallow. In cases where challenging lighting conditions and longdistances prevented the distinction between two species that are very similar and require closeinspection to identify, the less specific name was used if necessary, i.e. greater and lesser scaup orlong-billed and short-billed dowitchers were identified as unidentified scaup or unidentifieddowitchers.Avifauna observed during field surveys were recorded on field data sheets along with collectionlocation, time, and name of field observer. All field staff carried a field guide to avoidmisidentification of uncommon species. In order to avoid double counts of birds, individuals that wereobserved on the boundary of a zone or flying from one zone to another were recorded by only oneteam. This was determined by communicating directly with the other team by radio or phone. Ifcontact could not be made, the data were recorded and details noted on the data sheets. At the end ofeach survey, field staff reviewed the data sheets and, if necessary, corrections were made on the datasheets to avoid over-counting of individual birds.In some cases it was not possible to definitively assess whether a double-count had occurred,particularly with large flocks of highly transitory shorebirds and with raptors, which ranged over allsurvey zones and were seen on both survey days. In cases where an over-count is suspected, a note hasbeen made on the reported table of birds observed.All survey data were initially recorded in the field on hard copy data sheets and then transferred in theoffice to digital database files and checked for accuracy. The database was then queried to extractsummary information used to prepare tables and figures. Data will be analyzed further after moremonitoring intervals have occurred to identify spatial and temporal trends in total avian abundance,numbers of species, and patterns of habitat usage, activity, and seasonal variation.Attempts were made to locate results of previous avian monitoring programs within <strong>Bolsa</strong> <strong>Chica</strong> forcomparison. Prior western snowy plover (Charadrius alexandrinus nivosus) reports prepared by theU.S. Fish and Wildlife Service (Fancher, 1998; Fancher et al., 1998, 2001, 2002, 2004, 2005a, 2005b,2006) and the report on Belding’s Savannah sparrow (Passerculus sandwichensis beldingi) populationsin California (Zembal et al., 2006) were located and reviewed. Data collected during prior generalMerkel & Associates, Inc. 38
<strong>Bolsa</strong> <strong>Chica</strong> <strong>Lowlands</strong> Restoration <strong>Monitoring</strong><strong>2007</strong> <strong>Annual</strong> <strong>Report</strong>avian surveys of the site were not located. Data collected during recent and past Christmas bird countswill be sought and reviewed for comparison in future monitoring reports.ResultsOctober surveys counted a total of 7,256 individual birds representing 90 species, while Decembersurveys included a total of 9,333 individual birds representing 92 species (Tables 1-6 and 1-7).Although the represented species number is similar for the survey periods, there were 28 species thatwere only identified in one of the two survey periods. This change in species is due to the change inseason, with many migrating birds being observed in October and wintering birds observed inDecember. Each bird species observed was assigned to one of 9 ecological guilds (Appendix 1-D).The most abundant bird guild for both surveys was shorebirds with 4,406 individuals (61% of all birdsobserved) in October and 5,431 individuals (58% of all birds) in December (Figure 1-8). The mostnumerous shorebird species was black-bellied plover (Pluvialis squatarola) (1,678 individuals and23% of all species in October and 1,353 individuals and 15% of all species in December). It ispossible that the black-bellied plovers were over-counted in both quarters. The plovers tend to settle asa large flock to forage or loaf, and when disturbed they will split into several smaller flocks anddisperse throughout the FTB, Seasonal Ponds, and Muted Pocket Marsh. Even with careful notetakingand communication between teams, it is not possible to definitively prevent double-counts. It ispossible that the count could as much as double the actual number of black-bellied plovers. Westernsandpiper (Calidris mauri) were also numerous in December, with 1,270 individuals being identified.Other abundant shorebird species included dowitcher (Limnodromus sp.), dunlin (Calidris alpina),semipalmated plover (Charadrius semipalmatus), willet (Tringa semipalmata) and marbled godwit(Limosa fedoa).6000Number of Individuals5000400030002000October '07December '0710000Aerial FishForagersCoots andRailsDabblingDucks/GeeseDiving Ducks/Grebes/CormorantsGulls Herons Raptors Shorebirds UplandBirdsFigure 1-8. Avian abundance by guild for October and December <strong>2007</strong>.Merkel & Associates, Inc. 39
Change language