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2015-07-08 Saltworks

Biologists at Work - n/aIts always a pleasure to hang with the science team when they march through the levees at the Saltworks to survey the terns and skimmers nesting there. I’ve been lucky enough to take part in these walks since my time contributing the San Diego County Bird Atlas in 2003. The sensory overload that comes on a trek through 20,000 nesting Elegant Terns is not easily forgotten … ever. It’s the sights, the sounds, even the smells that overwhelm anyone who experiences such an encounter.

On this day Brian and Robert had guests. It was a crowd. Besides Brian, Robert, Kate and myself, were five students affiliated with the San Diego Zoo on this outing. The Elegant Tern chicks were nearly all hatched on this day so I held back while the rest of the crew walked the levee to investigate the colony. At this age, the chicks gather in large groups called creches. Since flight is an ability that they do not have at this age, they can easily be pushed into sticky mud or water, which is problematic to their well-being. By staying back there was an added advantage that I could use my long lens to record the team’s activities candidly.

Banding Black Skimmers was the focus of much of the team’s efforts this day, but Gull-Billed chicks got some attention as well. When the day was done, a good time was had by all.

Images in this set include Black Skimmers, Black Skimmer Eggs, Black-Necked Stilts, Elegant Terns, Forster’s Terns, Gull-Billed Terns,  Red-Necked Phalaropes, Belding’s Savannah Sparrows, Western Sandpiper and the Science Team at Work.

On July 10, Robert Patton added the following report:

Current status at saltworks for WSP is 83 total nests, 16 active; 31-37 chicks of 16-18 broods seen but likely more since not all areas thoroughly covered last visit.  This season’s nest and breeding adult numbers are a record highs for saltworks.  Although it likely reflects a redistribution of birds usually nesting at other sites, it also reflects the continuing trend of numbers gradually increasing in San Diego County.
For California Least Tern is 29 total nests, none active; at least 4-6 chicks and 4 fledglings seen.  The statewide population trend of California Least Terns continues to decline after peaking in the mid-2000s.
For Gull-Billed Tern is 33 total nests, 1 active (due to hatch); 15-20 chicks seen.  This dramatic recovery from the parasite-induced mass mortality event of 2013 is primarily due to the return of birds that had hatched at saltworks in 2011-2012 and had remained at wintering grounds in Mexico until they reached breeding age in 2014-2015.
Overall seabird numbers were low early in the season and nesting started much later than usual, suspected to be related to above average sea surface temperatures over winter and spring and resulting reduced prey fish availability.  Local numbers of birds and apparent fish availability increased in May to June.  Reports from the Gulf of California in mid-May reported that fisheries in the Midriff area had crashed due to high water temps and that elegant terns had not attempted to nest; they then showed up in record numbers in Southern California and began nesting here.
(See http://advances.sciencemag.org/content/1/5/e1400210  for previous fluctuations in elegant tern distribution).
Most nests of larger species have now hatched, with others abandoned or depredated, but most species currently have nests still active and chicks present.  Total numbers of nesting attempts including depredated eggs have not been tallied up yet, but the maximum number of nests active within a 2 week period are:
DC cormorant – 54
Caspian t – 229
Royal t – 192
Elegant t – 23928 (record high)
Forster’s t – 49 (+ 70 at CVWR)
Blk skimmer – 370 (+ 1 at CVWR)

Black-Necked stilt, Am avocet, killdeer, horned lark, Belding’s sav sparrow each have multiple nests and broods of chicks throughout.

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