ArnelGuanlao
Well-known member
Saturday morning, June 21, I joined the San Francisco
Bay Bird Observatory for a walk at the San Francisco
Bay National Wildlife Refuge in Alviso, California.
Located at the southern tip of San Francisco Bay, this
refuge's salt ponds, freshwater sloughs, and marshes
can attract thousands of ducks, shorebirds, and gulls
in the fall and winter months. Among them, there will
usually be small numbers of rarities for the area, such
as Eurasian Wigeon, Ruff, and Glaucous Gull.
Although June is the slowest time of the year for
the refuge, it is also the best time of the year to
see the refuge's resident birds raising their young.
I was especially curious to see how well the Black
Skimmers were doing in raising their young, as their
broods have experienced very high rates of failure
since the skimmers first tried nesting in the Bay
Area a decade ago.
We began the walk at the refuge's Environmental
Education Center (EEC) around 9:00 AM. The native
plant garden around the EEC did not contain anything
unusual; however, we did see a pair of KILLDEER
nesting near the parking lot in front of the EEC.
Their nest was the usual shallow scrape in the dirt,
in which four very well-camouflaged eggs had been
arranged to look like a small cluster of stones.
The poor parents were busy trying to distract us
with their broken-wing displays, so we decided to
leave them alone and head out on the boardwalk
through New Chicago Marsh, an expanse of saltwater
marsh that stretches to the west of the EEC for
maybe a half mile.
There were plenty of BLACK-NECKED STILTS and
AMERICAN AVOCETS in New Chicago Marsh; many of the
avocets were still sitting on their nests, but most
of the stilts were foraging actively in the marsh,
indicating that they had completed their nesting
for the year. We didn't see any stilt chicks
trailing behind their parents, so these chicks
were presumably hiding in the pickleweed - a smart
thing to do, with COMMON RAVENS flying back and
forth over the marsh and CALIFORNIA GULLS gathering
in the nearby salt ponds. However, we did see a few
nearly full-grown juveniles sitting on a patch of
mud near the boardwalk. They were close enough for
us to see the white edging to the brown feathers
on their backs - a telltale sign that they were
juveniles and not adults.
The boardwalk came to an end on the levee along
the southern perimeter of the large salt pond to
the immediate north of the EEC. In the past, this
pond was used for the commercial harvesting of
salt, but now it is used as a major nesting site
for FORSTER'S TERNS and AMERICAN AVOCETS. It is
also one of the known nesting sites for the BLACK
SKIMMERS.
On the mud islands at the center of this pond, we
could now see the nesting colony of terns, avocets,
and skimmers. Fortunately, chicks for all 3 species
were also present. Swimming in the pond, we saw an
adult American Avocet with three chicks trailing
behind it; two to three weeks old, these chicks
had already molted and now resembled their parents,
right down to the cinnamon coloring of their heads,
necks, and faces. On one of the mud islands, we saw
the fuzzy chicks of Forster's Terns snuggling up
against their parents' bodies for warmth and
protection. And nearby, we saw the Black Skimmers'
admittedly grotesque and awkward-looking chicks
begging for food from their parents.
The wildlife biologist leading the walk told us
that these skimmers have managed to raise 6 chicks
this year. One of these chicks died recently, and
two others seemed to be ill; nevertheless, these
are much better results than in previous years,
when very few of the eggs hatched, and nearly all
of the chicks died early. She attributed the higher
rate of egg hatching to the fact that the skimmers
have stopped partially burying their eggs in the
nesting substrate - a tactic that helps keep their
eggs warm on sandy beaches, but works poorly in the
heavy clay soil of these mud islands. In previous
years, spring rain would cause partially buried
eggs to sink in the clay soil, which would then
harden around the eggs as it dried. It would
then be impossible for the skimmers to turn their
eggs, resulting in a high rate of egg failure.
This year, the skimmers have learned to keep the
eggs on the ground, and so they have had more
success. The skimmers will undoubtedly have to
make more adaptations to their new home before
their numbers in the San Francisco Bay Area show
any appreciable gain.
The walk back to the EEC from the salt pond was
short and uneventful. We saw mainly the usual mix
of common birds for this time of the year - ANNA'S
HUMMINGBIRD, NORTHERN MOCKINGBIRD, BARN SWALLOW,
etc. However, on the drive out, I did see a pair
of BURROWING OWLS perched on the refuge's entrance
gate. To avoid stressing them, I paused only
briefly to take a look at them. Even so, they
were a nice way to end the visit and the morning.
More information about the San Francisco Bay
National Wildlife Refuge can be found at the
following links:
http://desfbay.fws.gov/
http://www.audubon.org/news/press_releases/0502-salt_ponds052902.html
http://areas.wildernet.com/pages/area.cfm?areaID=CADONEDNR&CU_ID=157
More information about the San Francisco Bay Bird
Observatory can be found at the following link:
http://www.sfbbo.org/
Good Birding!
Arnel Guanlao
-----------------------------------------------------
BIRD LIST
San Francisco Bay National Wildlife Refuge - Alviso
Santa Clara County, CA
6/21/2003
American White Pelican (Pelecanus erythrorhyncos)
Great Blue Heron (Ardea herodias)
Turkey Vulture (Cathartes aura)
Canada Goose (Branta canadensis)
Gadwall (Anas strepera)
Mallard (Anas platyrhyncos)
Cinnamon Teal (Anas cyanoptera)
Ring-necked Pheasant (Phasianus colchicus) [heard]
Killdeer (Charadrius vociferus)
Black-necked Stilt (Himantopus mexicanus)
American Avocet (Recurvirostra americana)
California Gull (Larus californicus)
Forster's Tern (Sterna forsteri)
Black Skimmer (Rhyncops niger)
Mourning Dove (Zenaida macroura)
Burrowing Owl (Athene cunicularia)
Anna's Hummingbird (Calypte anna)
Black Phoebe (Sayornis nigricans)
Common Raven (Corvus corax)
Cliff Swallow (Petrochelidon pyrrhonota)
Barn Swallow (Hirundo rustica)
Bushtit (Psaltriparus minimus)
Marsh Wren (Cistothorus palustris) [heard]
Northern Mockingbird (Mimus polyglottos)
European Starling (Sturnus vulgaris)
California Towhee (Pipilo crissalis)
Song Sparrow (Melospiza melodia)
Red-winged Blackbird (Agelaius phoeniceus)
House Finch (Carpodacus mexicanus)
American Goldfinch (Carduelis tristis)
Bay Bird Observatory for a walk at the San Francisco
Bay National Wildlife Refuge in Alviso, California.
Located at the southern tip of San Francisco Bay, this
refuge's salt ponds, freshwater sloughs, and marshes
can attract thousands of ducks, shorebirds, and gulls
in the fall and winter months. Among them, there will
usually be small numbers of rarities for the area, such
as Eurasian Wigeon, Ruff, and Glaucous Gull.
Although June is the slowest time of the year for
the refuge, it is also the best time of the year to
see the refuge's resident birds raising their young.
I was especially curious to see how well the Black
Skimmers were doing in raising their young, as their
broods have experienced very high rates of failure
since the skimmers first tried nesting in the Bay
Area a decade ago.
We began the walk at the refuge's Environmental
Education Center (EEC) around 9:00 AM. The native
plant garden around the EEC did not contain anything
unusual; however, we did see a pair of KILLDEER
nesting near the parking lot in front of the EEC.
Their nest was the usual shallow scrape in the dirt,
in which four very well-camouflaged eggs had been
arranged to look like a small cluster of stones.
The poor parents were busy trying to distract us
with their broken-wing displays, so we decided to
leave them alone and head out on the boardwalk
through New Chicago Marsh, an expanse of saltwater
marsh that stretches to the west of the EEC for
maybe a half mile.
There were plenty of BLACK-NECKED STILTS and
AMERICAN AVOCETS in New Chicago Marsh; many of the
avocets were still sitting on their nests, but most
of the stilts were foraging actively in the marsh,
indicating that they had completed their nesting
for the year. We didn't see any stilt chicks
trailing behind their parents, so these chicks
were presumably hiding in the pickleweed - a smart
thing to do, with COMMON RAVENS flying back and
forth over the marsh and CALIFORNIA GULLS gathering
in the nearby salt ponds. However, we did see a few
nearly full-grown juveniles sitting on a patch of
mud near the boardwalk. They were close enough for
us to see the white edging to the brown feathers
on their backs - a telltale sign that they were
juveniles and not adults.
The boardwalk came to an end on the levee along
the southern perimeter of the large salt pond to
the immediate north of the EEC. In the past, this
pond was used for the commercial harvesting of
salt, but now it is used as a major nesting site
for FORSTER'S TERNS and AMERICAN AVOCETS. It is
also one of the known nesting sites for the BLACK
SKIMMERS.
On the mud islands at the center of this pond, we
could now see the nesting colony of terns, avocets,
and skimmers. Fortunately, chicks for all 3 species
were also present. Swimming in the pond, we saw an
adult American Avocet with three chicks trailing
behind it; two to three weeks old, these chicks
had already molted and now resembled their parents,
right down to the cinnamon coloring of their heads,
necks, and faces. On one of the mud islands, we saw
the fuzzy chicks of Forster's Terns snuggling up
against their parents' bodies for warmth and
protection. And nearby, we saw the Black Skimmers'
admittedly grotesque and awkward-looking chicks
begging for food from their parents.
The wildlife biologist leading the walk told us
that these skimmers have managed to raise 6 chicks
this year. One of these chicks died recently, and
two others seemed to be ill; nevertheless, these
are much better results than in previous years,
when very few of the eggs hatched, and nearly all
of the chicks died early. She attributed the higher
rate of egg hatching to the fact that the skimmers
have stopped partially burying their eggs in the
nesting substrate - a tactic that helps keep their
eggs warm on sandy beaches, but works poorly in the
heavy clay soil of these mud islands. In previous
years, spring rain would cause partially buried
eggs to sink in the clay soil, which would then
harden around the eggs as it dried. It would
then be impossible for the skimmers to turn their
eggs, resulting in a high rate of egg failure.
This year, the skimmers have learned to keep the
eggs on the ground, and so they have had more
success. The skimmers will undoubtedly have to
make more adaptations to their new home before
their numbers in the San Francisco Bay Area show
any appreciable gain.
The walk back to the EEC from the salt pond was
short and uneventful. We saw mainly the usual mix
of common birds for this time of the year - ANNA'S
HUMMINGBIRD, NORTHERN MOCKINGBIRD, BARN SWALLOW,
etc. However, on the drive out, I did see a pair
of BURROWING OWLS perched on the refuge's entrance
gate. To avoid stressing them, I paused only
briefly to take a look at them. Even so, they
were a nice way to end the visit and the morning.
More information about the San Francisco Bay
National Wildlife Refuge can be found at the
following links:
http://desfbay.fws.gov/
http://www.audubon.org/news/press_releases/0502-salt_ponds052902.html
http://areas.wildernet.com/pages/area.cfm?areaID=CADONEDNR&CU_ID=157
More information about the San Francisco Bay Bird
Observatory can be found at the following link:
http://www.sfbbo.org/
Good Birding!
Arnel Guanlao
-----------------------------------------------------
BIRD LIST
San Francisco Bay National Wildlife Refuge - Alviso
Santa Clara County, CA
6/21/2003
American White Pelican (Pelecanus erythrorhyncos)
Great Blue Heron (Ardea herodias)
Turkey Vulture (Cathartes aura)
Canada Goose (Branta canadensis)
Gadwall (Anas strepera)
Mallard (Anas platyrhyncos)
Cinnamon Teal (Anas cyanoptera)
Ring-necked Pheasant (Phasianus colchicus) [heard]
Killdeer (Charadrius vociferus)
Black-necked Stilt (Himantopus mexicanus)
American Avocet (Recurvirostra americana)
California Gull (Larus californicus)
Forster's Tern (Sterna forsteri)
Black Skimmer (Rhyncops niger)
Mourning Dove (Zenaida macroura)
Burrowing Owl (Athene cunicularia)
Anna's Hummingbird (Calypte anna)
Black Phoebe (Sayornis nigricans)
Common Raven (Corvus corax)
Cliff Swallow (Petrochelidon pyrrhonota)
Barn Swallow (Hirundo rustica)
Bushtit (Psaltriparus minimus)
Marsh Wren (Cistothorus palustris) [heard]
Northern Mockingbird (Mimus polyglottos)
European Starling (Sturnus vulgaris)
California Towhee (Pipilo crissalis)
Song Sparrow (Melospiza melodia)
Red-winged Blackbird (Agelaius phoeniceus)
House Finch (Carpodacus mexicanus)
American Goldfinch (Carduelis tristis)