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

Western Snowy Plover Nesting at Bolsa Chica, 2008 December, 2008
initiated in mid April, one on NTI and one on STI. The third abandoned nest was initiated in mid-
July in Cell 19.
14
12
# of Nests
10
8
6
4
2
initiated
hatched
predated/lost
0
Mar 16-31
Apr 1-15
Apr 16-30
May 1-15
May 16-31
Jun 1-15
Jun 16-30
Survey Time Period
Jul 1-15
Jul 16-31
Aug 1-15
Figure 4. Biweekly Western Snowy Plover Nest Initiation, Hatching, & Loss at Bolsa Chica in
2008.
The abandoned nest on NTI was caused by harassment of the plover pair by elegant terns. The
plovers continuously failed to reach the protection of the ME over their eggs and after 2 days
abandoned the nest. In 2007, on NS1, 2 plover nests protected by an ME survived to hatch amongst
the elegant terns.
The nest abandoned on STI (Nest #19) was incubated by banded female WWYY. Prior to the
abandonment of Nest #19, Nest #12 hatched, but the brood was unattended by an adult. The chicks
from Nest # 12 gravitated to Nest #19 and, after initially attempting to drive off the chicks, the
female (WWYY) began to brood these chicks and to simultaneously incubate her own eggs. It was
apparent that she was confused by the situation and the next day after an adult from Nest #12
appeared and brooded its chicks, the female abandoned her Nest #19.
The nest in Cell 19, Nest # 65, was abandoned for unknown reasons. Subsequent examination of
eggs revealed semi-developed chicks.
A total of 193 snowy plover eggs were produced at Bolsa Chica in 2008, with 19 eggs abandoned,
predated, or failing to hatch. From the 193 total eggs, 174 chicks were produced. Of these 174 total
chicks produced in 2008, a minimum of 57 chicks (32.8%) and a maximum of 109 chicks (62.6%)
were estimated to have survived to fledge (Table 2). This is the highest number of hatched nests and
potentially the highest number of fledglings recorded at Bolsa Chica. Even the minimum number of
fledglings is surpassed only by 2004, 2005, and 2006 (Figure 5). Sixty-two nests survived to hatch
with a hatching success rate of 92.5%. This is the highest hatching success rate in all years surveyed
with the exception of 2007 at 96.0%.
Merkel & Associates, Inc. 11