San Francisco Bay National Wildlife Refuge (1 Viewer)

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)

Hi Arnel,

Why don't the reserve managers spread a ton or two of sand/gravel on the Skimmer nesting island? That's fairly common practice with artificial nesting islands for terns over here (if it was a natural site, I wouldn't suggest this, but this is after all an old industrial salt extraction site!)

Michael

Sounds like a great day out i would have seen 3 new birds.

Michael Frankis said:

Hi Arnel,

Why don't the reserve managers spread a ton or two of sand/gravel on the Skimmer nesting island? That's fairly common practice with artificial nesting islands for terns over here (if it was a natural site, I wouldn't suggest this, but this is after all an old industrial salt extraction site!)

Michael

Click to expand...

Perhaps they don't do this because the American Avocets
wouldn't nest there, and the American Avocets got there first?
Everywhere I've seen avocets nesting (around San Francisco
Bay, anyway), I see them nesting on barren mudflats that are
fairly devoid of rocks and gravel. I suspect they wouldn't like
nesting in gravel, although that is conjecture on my part. I
guess I'll have to ask the folks at SFBBO the next time I'm on
one of their walks.

Incidentally, the Black Skimmers apparently went through the
same kind of learning process when they colonized the Salton
Sea in southern California. So, even though it takes them a
while to learn, they do learn.

Hi Arnel,

I don't know about American Avocets, but ours (Pied Avocet) are definitely happy nesting on gravel / shingle, I think they prefer it (better camouflage for the eggs, too). Well worth a try, it needn't be the whole island, just a small area enough for a few pairs of skimmers & terns, say 30x30 feet

I'll be interested to hear what the SFBBO people think - it could even be that no-one has made the suggestion to them yet?

Michael

Their next walk is in a month, so I'll ask them then. Note,
however, that SFBBO is not directly tied with the refuge,
except in an advisory capacity. The refuge managers in
the US government may or may not take their advice into
consideration.

Another thought that occurred to me is that these mud
islands are actually dredged material from the bottom of
the salt pond. This material is constantly eroding back
into the pond, especially in the winter and spring, when
we get the rain. With the refuges getting as little funding
as they do these days, the cost of maintaining a gravel
bed on one of these islands may be problematic,
especially with some of the other projects going on in the
refuge. I do know that the refuge is currently trying to
increase habitat available for Burrowing Owls, a native
species that is in decline, and - of course - that costs
money.

Thanks for that info Arnel, sounds like a good spot.
We have relatives in sunnyvale so any local knowledge is useful,
hoping to visit soon when we can afford it.
Trying to lose weight so I can fax myself over and avoid the hassle of flying.

Gerry,

Wouldn't it be easier as an e-mail attachment? :-O

Michael

Late on Saturday, July 26, I made another visit to the San Francisco
Bay National Wildlife Refuge in Alviso, taking the same route that
I had taken on my previous trip there (on June 21). I arrived there
about an hour before the refuge closed for the day, so I rushed the
walk a bit and missed identifying a few species. Still, I did manage
to see some decent birds.

Nesting appeared to be largely done for the year, although there
was still a precocial BLACK-NECKED STILT chick wandering
around New Chicago Marsh under the watchful eyes of its parents.
On the mud islands in the salt pond north of the EEC, a few juvenile
FORSTER'S TERNS waited for their parents to return with food;
these young terns were nearly full grown, and should soon be
striking out on their own. The young BLACK SKIMMER at the
center of the easternmost mud island was now half the size of a
full adult. It was walking about the island, and seemed to be doing
well; however, it still retained its awkward appearance, with tail and
flight feathers that seemed to be one size too large for it.

The first migrant shorebirds had finally arrived, with roughly 100
adult WESTERN SANDPIPERS foraging in New Chicago Marsh.
Among them scurried a few LEAST SANDPIPERS, but (sadly)
no Semipalmateds. In the salt pond north of the EEC, 4 WILSON'S
PHALAROPES and 4 RED-NECKED PHALAROPES bobbed up
and down on the wind-driven waves. Most of the Wilson's
Phalaropes had already molted into basic plumage, but the Red-
necked Phalaropes still bore vestiges of their summer garb. I was
able to make some good comparisons of the two phalarope
species, as they frequently swam close together.

Finally, I checked the nest box that had been mounted in one of
the cottonwoods along Mallard Slough, a freshwater channel no
more than a hundred yards to the east of the EEC. This nest box
was occupied by a BARN OWL, who would occasionally poke its
head out to stare at me. On the drive out of the refuge, I looked
for the Burrowing Owls that have been hanging out recently near
the refuge's entrance gate, but saw no sign of them.

Good Birding!
Arnel Guanlao

___________________________________________

BIRD LIST
San Francisco Bay National Wildlife Refuge, Alviso
Santa Clara County, CA
7/26/2003

Snowy Egret (Egretta thula)
Canada Goose (Branta canadensis)
Killdeer (Charadrius vociferus)
Black-necked Stilt (Himantopus mexicanus)
American Avocet (Recurvirosta americana)
Western Sandpiper (Calidris mauri)
Least Sandpiper (Calidris minutilla)
Long-billed Dowitcher (Limnodromus scolopaceus)
Wilson's Phalarope (Phalaropus tricolor)
Red-necked Phalarope (Phalaropus lobatus)
Forster's Tern (Sterna forsteri)
Black Skimmer (Rhyncops niger)
Mourning Dove (Zenaida macroura)
Barn Owl (Tyto alba)
Barn Swallow (Hirundo rustica)
Bushtit (Psaltriparus minimus)
Northern Mockingbird (Mimus polyglottos)
California Towhee (Pipilo crissalis)
House Finch (Carpodacus mexicanus)

OTHER WILDLIFE:

Brush Rabbit (Sylvilagus bachmani)

Sunday, August 17, a friend and I spent the morning birding the San Francisco Bay National Wildlife Refuge in Alviso. We began with the shallow ponds along the western edge of New Chicago Marsh, which can be scoped from Spreckels Avenue in the small town of Alviso. Besides the many resident BLACK-NECKED STILTS and AMERICAN AVOCETS, we also saw large numbers of returning shorebirds that had come here to spend the night.

Most of the returning shorebirds were DOWITCHERS, all of them molting into basic plumage. The vast majority of these Dowitchers were fast asleep, although a few of them had awoken and were busy preening their feathers. They all remained silent, however, so we could not identify them to the species. A GREATER YELLOWLEGS and several LESSER YELLOWLEGS plodded among the snoozing masses of Dowitchers, occassionally stabbing the gray mud for a bit of food. And, in more open water away from the Dowitchers, 19 WILSON'S PHALAROPES spun about in circles, as they foraged for their morning meal.

After it became apparent that there wasn't all that much variety in this set of ponds, we decided to walk along the railroad tracks that bisect New Chicago Marsh, in search of the Ruff that had been recently seen in this area. This Ruff has spent the winter here for the last 3 years, and every year, I have gone out to look for it, only to come away empty-handed. This year, that fine tradition has so far continued: we looked and looked for the Ruff, but could not find it, no matter how hard we tried. The bird certainly had many places to hide here, in terrain that was frequently obscured by dense mats of pickleweed and riddled with sloughs and small ponds.

It was probably a good thing that the Ruff was hiding, for about a half hour after we arrived, a PEREGRINE FALCON suddenly appeared in the sky above us. It hovered for just a moment above a small pond no more than 30 feet away; then, with amazing agility, it plummeted from the sky like a thunderbolt. A confusing blur of sinew and feather, the peregrine struck a hapless dowitcher that had been foraging in this pond, killing it instantly. As shorebirds streamed from the area in a mass panic, the peregrine propelled itself into the sky, with the limp body of the Dowitcher clenched firmly in its talons.

We were hoping that the peregrine had flushed the Ruff out of its hiding spot for us, but all it had really done was clear the shorebirds from the immediate area. It was probably just as well, for we hadn't seen anything new - just the same mix of shorebirds that we had seen in the ponds along Spreckels Avenue. Consequently, we decided to head into the refuge and bird the area around the refuge's Environmental Education Center (EEC). As the gate into the refuge was inexplicably locked (it is usually open all day on Sundays), we made the long walk down the access road to the EEC, observing a gorgeous pair of RED-TAILED HAWKS along the way.

At the EEC, we took the boardwalk out into the eastern third of New Chicago Marsh. The only returning shorebirds there were 150 to 200 LEAST and WESTERN SANDPIPERS. They were foraging fairly close to the boardwalk, so we decided to scope them for a while, comparing their field marks and examining their molt patterns. Sadly, there wasn't a single Semipalmated Sandpiper lurking amongst them. As a consolation prize, however, we did see 9 AMERICAN WHITE PELICANS soaring overhead in formation, always an amazing sight.

After about a half hour, we followed the boardwalk out to the levee on the edge of the large salt pond north of the EEC. This salt pond contained nothing but CALIFORNIA GULLS, who had moved in after all of the nesting Forster's Terns had departed. The young Black Skimmer that had been raised here fledged a week earlier, so both it and its parents were nowhere to be seen. Presumably, its parents were teaching it how to fish somewhere on the open waters of San Francisco Bay.

Finally, we took the dirt trail back to the EEC, making a short stop to see if there were any Barn Owls in the nest box along Mallard Slough. There was no sign of them there, so we continued on, making the long and uneventful walk back to our cars.


Good Birding!
Arnel Guanlao


_________________________________________________

BIRD LIST
San Francisco Bay National Wildlife Refuge, Alviso
Santa Clara County, CA
8/17/2003

American White Pelican (Pelecanus erythrorhyncos)
Snowy Egret (Egretta thula)
Turkey Vulture (Cathartes aura)
Mallard (Anas platyrhyncos)
Northern Harrier (Circus cyaneus)
Red-tailed Hawk (Buteo jamaicensis)
Peregrine Falcon (Falco peregrinus)
Killdeer (Charadrius voociferus)
Black-necked Stilt (Himantopus mexicanus)
American Avocet (Recurvirostra americana)
Greater Yellowlegs (Tringa melanoleuca)
Lesser Yellowlegs (Tringa flavipes)
Long-billed Curlew (Numenius americanus)
Western Sandpiper (Calidris mauri)
Least Sandpiper (Calidris minutilla)
Dowitcher sp. (Limnodromus sp.)
Wilson's Phalarope (Phalaropus tricolor)
California Gull (Larus californicus)
Western Gull (Larus occidentalis)
Rock Dove (Columba livia)
Mourning Dove (Zenaida macroura)
Anna's Hummingbird (Calypte anna)
Black Phoebe (Sayornis nigricans)
Common Raven (Corvus corax)
Barn Swallow (Hirundo rustica)
Bushtit (Psaltriparus minimus)
Northern Mockingbrd (Mimus polyglottos)
European Starling (Sturnus vulgaris)
Common Yellowthroat (Geothlypis trichas)
Red-winged Blackbird (Agelaius phoeniceus)
House Finch (Carpodacus mexicanus)