2010 Nesting Season - Biodiversity Centre for Wildlife Studies

Western Grebes at Duck Lake in the
Creston valley had an unsuccessful breeding
season due to weather events (see Long-term
Monitoring page 52).
Finding a Sandhill Crane nest is always
a highlight for any nest finder. It was really
disappointing then for Wayne Campbell to
discover two nests in Cariboo marshes that
had recently been predated by Common Ravens
(Figure 26).
Figure 24. In 2009, a pair of American Avocets
nested on a small islet in this lake along the
Meadow Lake Road in the south Cariboo
region. In 2010, water had receded significantly
exposing large expanses of alkaline shores.
Avocets abandoned the area. 22 June 2010 (R.
Wayne Campbell).
At a new site in the southeastern fringes of
the Cariboo region, a pair of avocets selected a
shore location to nest in late May. The site was
only 10 metres from water but by late June the
nest site was more than 50 metres from water
and no adults (or young) were seen.
At some locations, Red-necked Grebes
delayed egg-laying with unstable water levels.
This was really evident at Stump Lake where
a thriving colony has now been reduced to
isolated pairs trying to find flotsam upon which
to build their nests. At 108 Mile Lake, several
pairs finally started building nests and laying
eggs in mid-June with the site only a few metres
from shore (Figure 25).
Figure 25. After several attempts to build a
nest among aquatic surface vegetation, this
pair of Red-necked Grebes built a nest in only
nine inches of water and during incubation the
site became high and dry. 108 Mile Lake, BC. 6
June 2010 (Photo by R. Wayne Campbell).
Figure 26. Predated Sandhill Crane eggs. Near
Riske Creek, BC. 16 June 2010 (Photo by R.
Wayne Campbell).
Nesting Yellow-headed Blackbirds had
varying success depending on which part of the
province was being visited. Due to the late and
stormy spring, most colonies at high elevations
had poor success, some as high as 75% failure
compared to surveys in 2009. At lower elevations
in the Okanagan Valley, reproductive success
was above average (65 to 85%) while at some
sites in the Thompson-Nicola region of the
south-central interior high water levels were
a problem. This was a combination of spring
runoff and ranchers maintaining overflow in
aquatic systems for irrigation purposes. At one
site, less than 20% of nesting Yellow-headed
Blackbirds fledged young compared to totals in
2009 (Figure 27).
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