June 22, 2007
RIVER WATCHER
THE BRINK OF THE BANK
SWALLOW
Rex Burress
The environmentally aware manager of the Avenue 9 art gallery in Chico,
Maria Phillips, reminded me of the dilemma of the Bank Swallow. One of her
photographs, taken by Dawn Garcia, showed a colony occupying an embankment, a
rare sight in recent years as it seems a scarcity of banks has developed, much
like animals finding fewer tree crevice homes.
The Bank Swallow, (Riparia riparia), is the most stressed
of the swallow family and has been listed as threatened in California,
primarily because its major habitat, the Sacramento River corridor, has fewer
bare banks because they have been extensively rip-rapped with rock for flood
control. Up to 80% of CA’s bank swallows are found along the Sacramento, and
50% are threatened by river projects.
The tiny bank swallow, the smallest of 74 swallow and martin
species found around the world, gallantly undertakes a laborious task of
digging a three to four foot tunnel into an embankment where a nest is tended
in darkness at the end at end. The birds are sensitive to intrusion, and since
they often build their tunnels near the top of a bank, they can cave in under
heavy weight. The packed dirt is pecked and clawed determinedly until the nest
is built, the only swallow to dig a hole. In CA, Cliff Swallows build mud nests
under bridges, Rough Winged Swallows use found holes, Tree Swallows use tree
cavities, and Barn Swallows built a mud/fiber nest on manmade structures, but
they all soar and swoop for a living, spending more time in the air than
perching...and they all consume large numbers of insects caught on the wing!
I observed one pair of bank swallows construct a hole/nest in a
rough flood-eroded bank opposite the Oroville Dam one year. Usually they gather
in colonies, but this one pair chose a difficult site to dig their hole. Tall
sheer dirt banks are rare along the Feather River watershed, forcing them to
use a-less-than-perfect place. I could lean over the edge of the bank and run
my arm into the finalized excavation, and I marveled that I couldn’t reach the
end of the narrow run through pebbly soil. Once in Missouri boyhood when I was
an egg collector, I scaled a cliff to reach back into a bank swallow burrow to
obtain a pearl-white egg.
I have seen the excavations of the colony at Fort Funston on the
beach cliffs just south of the San Francisco Zoo. In 1988, a 12 acre refuge was
made of that cliff area to help save the birds that were being affected by
human intrusion. They also contend with the severe winds that buffet the sea
edge, and starlings sometimes steal their holes. Numbers decreased from 500 to
140 between 1993 to 1996. They feed over nearby Lake Merced and share the air
with gulls and hang gliders. The only other coastal colony is at Ano Nuevo
State Park.
The tiny bank swallow is a neotropic bird, migrating to South
America each year, and returning in mass to northern nesting sites in April.
The energetic life of a swallow is devoted to flying as if spiritually obsessed
to living on the wing. And what greater privilege than to have wings able to
lift the bird above earthly conflicts and mingle with the heavenly chorus!
"Oh that I
had wings like a dove! For then would I fly away
and be at
rest."
Psalm 55:6