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

Bolsa Chica Lowlands Restoration Monitoring
2008 Annual Report
Western Snowy Plover
The complete 2008 results for the western snowy plover breeding season at Bolsa Chica can be read in
the annual report (Knapp and Peterson 2008)(Appendix 1-G).
The western snowy plover initiated its first nest on March 17, 2008 and the last nest hatched on August
9. The plovers nested on STI, NS1, NS3, and a number of zones within the Seasonal Ponds (Table 1-
23). A total of 67 nests were located at Bolsa Chica. Four completed clutches were 2-egg clutches,
while 61 were 3-egg clutches. The remaining 2 nests were depredated prior to nest completion. From
the 193 total eggs laid, 174 chicks were produced. Two of the 67 total nest attempts were lost to
predators, one on Zone 22 early in the season and one on NS1. These nests were depredated prior to
placement of the mini-exclosure over the nest. The probable predators for these nests were corvid and
gull, respectively. Three nests, one with 3 eggs and two with 2 eggs, were abandoned. These nests
were located on STI, NTI, and Zone 19, respectively. Of the 174 total chicks produced in 2008, a
minimum of 57 and a maximum of 109 chicks (32.8 to 62.6%) were estimated to have survived to
fledge.
The minimum fledgling estimate per nest (0.85) is slightly below the average (0.95) of the study years.
The maximum estimate of fledglings per nest (1.62) would exceed the previous high of 1.47 in 2005.
Of the 67 nests, 24 nests did not fledge chicks. Of the 19 known nests producing chicks but not
producing fledglings, one brood was depredated by gulls and one brood by coyote. The remaining 17
broods were most likely depredated by red-tailed hawk (STI) or American kestrel (Seasonal Ponds).
There was potential for trampling of the chicks on NS1 due to overcrowding.
Table 1-23. 2008 Western snowy plover reproductive success for each nesting location.
Location Total Nests Nests Failed*
Nests Hatched
(# chicks)
Fledglings
Nest Site 1 37 1 36 (100) 33-83
Seasonal Ponds: 20 2 18 (51) 18
Cell 9 1 0 1 (3) 3
Cell 10 3 0 3 (8) 1
Cell 12 3 0 3 (8) 6
Cell 19 4 1 3 (9) 3
Cell 22 6 1 5 (15) 2
Road 3 0 3 (8) 3
Nest Site 3 5 0 5 (14) 3-5
North Tern Island 1 1 0 (0) 0
South Tern Island 4 1 3 (9) 3
Total 67 5 62 (174) 57-109
Merkel & Associates, Inc. 94