2008 Annual Monitoring Report (pdf 10.9MB) - Bolsa Chica ...

More documents

Recommendations

Info

Bolsa Chica Lowlands Restoration Monitoring 2008 Annual Report and April surveys. Northern shoveler was present in small numbers only during the surveys in June and August. Several brant (Branta bernicla) were recorded foraging in eelgrass in the FTB. The third most abundant guild in 2008 was upland birds, primarily due to the inclusion of Savannah sparrow (Passerculus sandwichensis) in this guild, including both the Belding’s Savannah sparrow, a species that remains in the salt marsh year round, and any other migrating Savannah sparrows. The number of individuals in the guild remained fairly stable for the entire year although there was a small drop in numbers during April (711 individuals) and August (671 individuals). June had the highest count of upland birds with 1,244 individuals and made up 32.6% of all birds observed during that survey. Counts during the winter months were comparable to the June count including; 1,162 individuals (13% of all birds) in October, 1,012 individuals (9% of all birds) in December, and 1,106 individuals in February. The highest numbers for Savannah sparrow were during the month of October when a total of 639 individuals were counted. February and August, which correspond with the beginning and end of the Belding’s Savannah sparrow breeding season, were the lowest numbers with 156 individuals observed. June counts were much higher at 416 individuals. Other abundant upland species include house finch (Carpodacus mexicanus), and mourning dove (Zenaida macroura). Cliff swallow (Petrochelidon pyrrhonota), northern rough-winged swallow (Stelgidopteryx serripennis), barn swallow (Hirundo rustica), violet-green swallow Tachycineta thalassina, and tree swallow (Tachycineta bicolor) were all observed at Bolsa Chica although the highest counts of each species were observed at different times of the year. Northern-rough winged swallow (83 individuals) and violet-green swallow (42 individuals) were most numerous in February. Tree swallow was most numerous in both February and December with 23 individuals observed each month. Cliff swallow were most numerous in June (222 individuals) and barn swallow most numerous in August (107 individuals). The great-tailed grackle (Quiscalus mexicanus), not native to the area but an invading species from Sonora or southern Arizona, was observed breeding during April and June surveys but was not observed during any other surveys. Aerial fish foragers were the fourth most abundant guild and accounted for 8.8% of all birds observed over the year. The elegant tern was the most common, accounting for 62.1% of all aerial fish foragers. The majority of the remaining species in this category included; in descending order of abundance, black skimmer, Forster’s tern (Sterna forsteri), Caspian tern, California least tern, and royal tern. All of these species nest at Bolsa Chica in the area of the FTB and had their highest numbers during the June survey. These species were most likely undercounted during June and August due to limited access to their high-density nesting area in Zone 71 (Nest Site 1). It is important to note that the elegant tern count (maximum of 1,330 in April 2008) only reflects their usage of Zone 71, which represents only a small portion of the total breeding population at the Bolsa Chica Ecological Reserve. The majority of elegant terns nested at North Tern Island in Inner Bolsa Bay, outside the survey focus of this monitoring program (see Figure 0-1). An estimated 7,000 elegant tern nested on NTI in 2008 (Mike Horn, pers. comm.). Other aerial fish foragers included belted kingfisher (Megaceryl alcyon), which were seen in low numbers, and brown pelican (Pelecanus occidentalis), which were observed loafing and foraging nearly year-round (none detected in February) in moderate numbers. Diving ducks/grebes/cormorants were the fifth most abundant guild and accounted for 4.9% of all birds observed over the year. Ruddy duck was the most common diving duck accounting for 46.6% of Merkel & Associates, Inc. 81
Bolsa Chica Lowlands Restoration Monitoring 2008 Annual Report all individuals in this category, with the majority found during the February and April surveys. Other common birds in this guild were surf scoter (Melanitta perspicillata), bufflehead (Bucephala albeola), scaup (Aythya sp.), ruddy duck, and eared grebe (Podiceps nigricollis). Double-crested cormorant (Phalacrocorax auritus) were also a common species in this category. They were observed year round, even nesting on the site, but were observed in higher numbers during the winter months of October through February. The remaining guilds were represented in the following order of descending abundance: gulls, coots and rails, herons, and raptors. Coots and rails were primarily American coot. A notable member of the heron guild was the reddish egret (Egretta rufescens), regularly seen in the FTB and Muted Pocket Marsh. Raptors are normally lowest in number due to their position in the food chain. They are also among the more likely to be over-counted due to their mobility and size of their territories. Attempts were made between surveyors to eliminate overcounts; however, this is difficult over time and between consecutive survey days. Eleven species of raptor were observed in 2008 including red-tailed hawk (Buteo jamaicensis), turkey vulture (Cathartes aura), American kestrel (Falco sparverius), osprey (Pandion haliaetus), northern harrier (Circus cyaneus), Cooper’s hawk (Accipiter cooperii), whitetailed kite (Elanus leucurus), peregrine falcon (Falco peregrinus), sharp-shinned hawk (Accipiter striatus), burrowing owl (Athene cunicularia), and merlin (Falco columbarius). Avian Usage of the Survey Area Assessing the avian usage of Bolsa Chica is complicated due to the frequent movements of the shorebirds and waterfowl between areas such as the Seasonal Ponds and FTB within and between days. However a general overview of the use of these areas is provided. Full Tidal Basin The 158-ha FTB is the largest, and was the most highly utilized, portion of the site. A total of 25,413 individuals (49.7% of all birds observed), representing 103 species, were counted in the basin in 2008. The heavy usage of this area was strongly linked to the low tidal elevation during which the surveys were always conducted. During low tide, shorebirds (which made up 72.1% of all birds) foraged on the intertidal mudflats along the eastern shore of the basin (cordgrass bench), southwestern shoreline (Nest Site 1), and around Rabbit Island. Gulls utilized the exposed mudflats for loafing during the low tides. As the tide rose at the end of the surveys, many of the shorebirds and loafing gulls and pelicans would move to the zones east of the FTB berm once the mudflat was flooded in the FTB. This high tide usage is not reflected in the present dataset due to intentional low tide timing. Nest Site 1 in the FTB was highly utilized by aerial fish foragers, particularly during the April through August surveys when the terns and skimmers were nesting. Overall 94% of all aerial fish foragers were recorded in the FTB. Current research by California State University Fullerton has been examining usage of the FTB by terns, particularly elegant terns, and found foraging activity to be rather limited in the FTB, with the birds foraging primarily in the ocean. During the present 2008 monitoring, a total of only 15 elegant terns were documented foraging in the FTB. Among the other terns, there were 15 least tern, 8 Caspian tern, 38 Forster’s tern, four royal tern, and 26 black skimmer documented foraging in the FTB. Merkel & Associates, Inc. 82
Page 2 and 3:
Bolsa Chica Lowlands Restoration Pr
Page 4 and 5:
Bolsa Chica Lowlands Restoration Mo
Page 6 and 7:
Page 8 and 9:
Page 10 and 11:
Page 12 and 13:
Page 14 and 15:
Page 16 and 17:
Page 18 and 19:
Page 20 and 21:
Santa Barbara Los Angeles Outer Bol
Page 22 and 23:
Page 24 and 25:
Page 26 and 27:
Page 28 and 29:
Page 30 and 31:
Page 32 and 33:
Page 34 and 35:
Page 36 and 37: Bolsa Chica Lowlands Restoration Mo
Page 44 and 45: BS PM Rep3 Muted Pocket Marsh BS PM
Page 58 and 59: Topsmelt January April July October
Page 74 and 75: 22 Temperature 20 Temperature (C) 1
Page 78 and 79: PM 50 66 47 Full Tidal Basin Future
Page 94 and 95: Zone PM 2 9 10 11 12 13 14 19 20 21
Page 108 and 109: Aug06 to Jan07 Jan07 to Jun07 assum
Page 136 and 137:
Page 138 and 139:
Page 140 and 141:
Page 142 and 143:
Page 144 and 145:
Page 146 and 147:
Page 148 and 149:
Page 150 and 151:
Page 152 and 153:
Page 154 and 155:
Page 156 and 157:
Page 158 and 159:
Page 160 and 161:
Page 162 and 163:
Page 164 and 165:
Page 166 and 167:
Page 168 and 169:
Total Future Full Tidal Basin FFTB
Page 170 and 171:
Page 172 and 173:
Western Snowy Plover Nesting at Bol
Page 174 and 175:
Page 176 and 177:
Page 178 and 179:
Page 180 and 181:
Page 182 and 183:
Page 184 and 185:
Page 186 and 187:
Page 188 and 189:
Page 190 and 191:
Page 192 and 193:
Page 194 and 195:
Page 196 and 197:
Page 198 and 199:
Page 200 and 201:
Page 202 and 203:
Page 204 and 205:
Page 206 and 207:
Page 208 and 209:
Page 210 and 211:
Page 212 and 213:
Page 214 and 215:
Page 216 and 217:
Page 218 and 219:
Page 220 and 221:
Page 222 and 223:
Page 224 and 225:
Page 226 and 227:
Page 228 and 229:
Page 230 and 231:
Page 232 and 233:
Page 234 and 235:
Page 236 and 237:
Page 238 and 239:
Page 240 and 241:
Page 242 and 243:
Page 244 and 245:
Page 246 and 247:
Page 248 and 249:
Page 250 and 251:
Page 252 and 253:
Page 254 and 255:
Page 256 and 257:
Page 258 and 259:
Page 260 and 261:
Page 262:
show all

2008 Annual Monitoring Report (pdf 10.9MB) - Bolsa Chica ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?