2007 Annual Monitoring Report (pdf 16MB) - Bolsa Chica Lowlands ...

Bolsa Chica Lowlands Restoration Monitoring2007 Annual ReportBasin) occupy the northeastern section of Bolsa Chica. These zones generally contain less salt panne,with broad expanses of pickleweed that are not yet exposed to tidal influence. The portions of thesezones closest to the residential neighborhoods have an increased amount of weedy species, particularlyZone 47. Zones 68 through 73 are located within the FTB and are subject to full tidal influence. Zone68 (Rabbit Island) is located on the western portion of the site between Inner Bolsa Bay and the FTB.This zone previously had more habitat diversity than most of the other zones, with salt marsh, alkalimarsh, and upland plant species. The introduction of tidal influence in August 2006 has resulted in theinundation of much of Rabbit Island during high spring tides, causing the existing low elevationhabitats to die off as the area transitions into mudflats and low to middle marsh habitats. Zone 69borders Rabbit Island to the east. Zone 71 is the newly created California least tern and western snowyplover nesting site, Nest Site 1. Zone 71 is a relatively unvegetated, sandy strip that gently slopestowards the FTB. The remaining zones include the intertidal mudflat shelf on the eastern shore andopen water bounded by riprap along the shoreline. The Muted Pocket Marsh occurs north of RabbitIsland and is not hydrologically connected to the Bolsa Chica Lowlands; rather is experiences a mutedtidal influence through a restricted tidal inlet leading to Outer Bolsa Bay. This area is shallowintertidal and subtidal with salt marsh at the higher elevations. The northern shore of the Muted PocketMarsh in lined with large eucalyptus trees that died when tidal influence was introduced. The deadtrees that remain provide abundant roosting and perching habitat for multiple bird species that use themarsh.Survey MethodologyThe Muted Tidal Basins (MTB), Future Full Tidal Basin (FFTB), and Seasonal Ponds (Zones 1through 66) were surveyed on foot by teams of field biologists. The FTB (Zones 68 through 73) wassurveyed primarily by vehicles, with multiple stops to view and record birds with the exception ofZone 68 and 71. The southern and western side of Zone 68 was surveyed by foot along a pedestrianfoot trail. Zone 71, which is a breeding colony for terns and shorebirds, and the Muted Pocket Marshwas surveyed on foot.Birding in the muted tidal basins.Surveys began in October 2007 to mark the start of Year 2 of themonitoring program and will continue every other month for a 2-yearperiod. Surveys were conducted over a two-day period at each surveyinterval in such a way as to minimize the possibility of double-countsbetween the two days. The FTB, Seasonal Ponds, and Muted Pocket Marshwere surveyed the first day, and the FFTB and MTBs surveyed the secondday. The surveys were conducted during a tide low enough to expose themudflat on the eastern shore of the FTB, referred to often as the cordgrassbench, generally within a predicted oceanic tide range of +1.2 to +0.3m (+4to +1 ft) NAVD88. At this tide, the large sand shoals that have formed inthe inlet of the FTB where large numbers of gulls, cormorants, and pelicansloaf in the afternoon were not exposed.October surveys were conducted on October 17 and 18, 2007. December surveys were conducted onDecember 3 and 4, 2007. The tide range during those surveys was+1.2 to +0.3m (+4 to +1 ft)NAVD88. Although logging tide gauges were in place in the FTB to document tidal lag and muting,those data were not available at the time of the survey; therefore predicted oceanic tides were used.The aim was to survey the FTB and Muted Pocket Marsh on a falling tide that exposed the mid- tohigh intertidal flats.Merkel & Associates, Inc. 37