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

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Bolsa Chica Lowlands Restoration Monitoring2007 Annual ReportWestern Snowy PloverThe complete 2007 results for the western snowy plover breeding season atBolsa Chica can be read in the annual report (Knapp et al. 2007)(Appendix 1-G).The western snowy plover initiated its first nest on April 9, 2007 and the last nesthatched on August 12. The plovers nested on STI, NS1, NS3, and a number ofcells within the Seasonal Ponds (Table 1-9). The snowy plover did not nest onNTI or NS2. A total of 50 nests were located at Bolsa Chica. Seven completedclutches were 2-egg clutches, while 43 were 3-egg clutches. From the 143 totaleggs produced, 130 chicks were produced. None of the 50 total nest attemptswere lost to predators, however, 2 complete clutches, one with 3 eggs and onewith 2 eggs, failed to hatch. The 2 nests that were abandoned appear to beunrelated to each other. One was located on NS1 and was found on June 8. Thesecond abandoned nest was located in Cell 32 and was found on June 28. Ofthese 130 total chicks produced in 2007, a maximum of 25 chicks (19.2%) wereestimated to have survived to fledge.Male snowy plover with newlyhatched chick and unhatchedegg. Photo Peter Knapp.Table 1-9. 2007 Western Snowy Plover Nests, Nest Fate, and Reproductive Success Distribution by Cell andNest SiteLocation Total Nests Nests Failed*Nests Hatched(# chicks)FledglingsNest Site 1 19 1 18 (50) 17Nest Site 3 8 0 8 (21) 3Cell 11 6 0 6 (17) 4Cell 32 4 1 3 (7) 0South Tern Island 4 0 4 (11) 0Cell 13 3 0 3 (8) 0Cell 22 3 0 3 (9) 13 other areas 3 0 3 (7) 0Total 50 2 48 (130) 25*Both nest failures in 2007 were due to nest abandonment.Fledglings per nest (0.50 fledglings/nest) ranked the lowest out of 10 years of fledgling estimates. Onehundred five chicks were most likely lost to predation. Of this loss, the only documented take was byAmerican kestrel: one on NS1 and the other in the Seasonal Pond area. The most likely cause ofsnowy plover chick mortality in 2007 continued to be kestrels, as in prior years. They were relativelyabundant and can do great harm very quickly. Other chicks were potentially lost to predation bycommon raven, coyote, black-crowned night heron, and black skimmers. Raven loss was estimated at6 chicks by indirect signs. The loss to coyotes is estimated at one brood of 3 chicks that hatchedcoincident with coyote/pup activity on NS3. Coyote tracks substantiate the probable loss. The loss toblack-crowned night heron, as recorded for the California least tern, is probable on ST1 and possiblyon NS1. Heron tracks indicated widespread hunting coincident with chick production and loss of 13chicks. The probable loss of chicks to black skimmers was on NS1, where a total of 13 chicks wereMerkel & Associates, Inc. 55
Bolsa Chica Lowlands Restoration Monitoring2007 Annual Reportlost. Coincident with least tern chick loss in this area of NS1, 5 snowy plover nests protected by MEssuccessfully hatched; however, the chicks were never observed post-hatching.DiscussionReproductive success at Bolsa Chica for both the California least tern and western snowy plover wasextremely low in 2007. This is largely due to loss of nests and/or chicks to depredation within theproject area and black skimmer activity on NS1. The western snowy plover did not lose any nests topredation as a result of protection of the nests by the use of MEs. However, chick losses were stillvery high post-hatching.Management of the California least tern and western snowy plover nesting sites is expected to beadaptive due to enhancement of the Bolsa Chica area and the creation of new nesting and foragingareas. Management recommendations in 2007 were made to increase reproductive success and toenhance the newly created nesting sites (Knapp and O’Reilly 2007, Knapp et a.l, 2007). NS1 washighly utilized for nesting by a number of species including elegant tern, black skimmer, and Americanavocet (Recurvirostra americana). Black skimmers are the only species that appear to be detrimentalto California least tern and western snowy plover. Confinement of the skimmers by utilizing chickfence to separate the nesting species would be recommended in the event that the skimmers continueutilize NS1 in subsequent years. Increased cover in the form of vegetation and debris would decreaseleast terns and snowy plovers chick exposure to predators, lowering predation and aiding in increasedforaging areas for snowy plovers. Night surveys by predator control staff may increase chances ofdetermining and discouraging night predators, such as the black-crowned night heron, by detectingpredation early and limiting their activity. NS2 and NS3 are currently not utilized by the least tern andmay not be suitable for increasing reproductive success without further management.Merkel & Associates, Inc. 56
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BOLSA CHICA LOWLANDSRESTORATION PRO
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Bolsa Chica Lowlands Restoration Mo
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Page 20 and 21: MutedPocket MarshSTATION 1wq1STATIO
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Sampling Location CoordinatesCalifo
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Cordgrass Transplant in Bolsa Chica
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Shorebirds (cont'd)Upland birdsRudd
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2007 Breeding Season for the Califo
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Final ReportWestern Snowy Plover Ne
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StudyAreaMeters0 250 500 1,000Figur
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2007 Nest LocationsNest LocationAt
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Western Snowy Plover Nesting at Bol
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