Notes on Thrashers
at
40 Selborne Drive
Piedmont, California.
Feb. 1933
Topography of habitat.
The house at this place occupies the top of a rocky spur having
its principal axis running practically east and west. The spur pro-
jects from somewhat higher hills to the east and is virtually exposed
to all points of the compass. The property is roughly elliptical in
outlines with a major axis approximately 500 feet long and minor axis
of about 190 feet. The major axis is along the crest of the spur, so
that the ground falls off sharply in all directions, except to the east
where it forms a saddle where the ridge connects with the higher hills.
To the west is a canyon.(Indian Gulch originally, but now bearing
the hybridized sophistic-aesthetic commercialized name of Trestle
Glen imposed upon it about 40 years ago by a street railway organization
anxious to efface all pioneer crudities in its newly awakened civic
consciousness,and incidentally,attract picnickers to the terminus of
the railway leading into the canyon).
Location.
The spur projects out into this canyon like a peninsula and over-
looks practically all of San Francisco Bay to the north, west and south,
from Richmond to San Jose and all of the cities and towns between. Its
elevation is somewhat more than 500 feet above sea level. The latitude
is approximately 37 degrees 48 minutes N.; longitude about 122 degrees
13 minutes W. There is a difference in elevation between the highest
and lowest points on the property of about 55 feet.
Elevation.
When the property was acquired it was inaccessible except by
trail. There were no streets nearer than a quarter of a mile from its
center, although there was a seldom used road about half as far away.
Natural growth.
Except for a few open spaces, the entire top and western slope
and the upper portion of the southern slope were covered with a dense
growth of live oak (mostly stunted and gnarled through aridity and
shallowness of soil) California laurel, hazel, poison oak, toyon,
coyote brush (Baccharis), gooseberry, currant, old man (California
Coast Sage), monkey flower, cascara (Rhamnus Californica) and Monterey
pines along the northern boundary. The pines were planted there,
probably about 30 years ago, as they are not native to this section.
The smaller growth consisted of bracken, naturalized broom,
snow berry, yerba buena, strawberry, shooting stars (Dodecatheon),
hound's tongue, fritillaria, blue-eyed grass, rein orchid, pimpernel
(some of which were blue), poppies, brodiaea capitata, harvest brodiaea,
immense quantities of soap plant (Amole, chlorogalum, furnishing an
important fiber for birds' nests), pussy paws, columbine, blackberry,
mustard, wild radish, deer-weed (hosackia), bush lupine, wild pea,
wild hollyhock(checker-bloom), mule's ears, honeysuckle, golden eggs
(Oenothera ovata), wood-fern, golden-backed fern and brake.
The old oak
The pines are perhaps 40 or 50 feet high. The oaks in the thick-
ets 15 to 20 feet. A few more or less isolated oaks are from 25 to
30 feet high where growing conditions --although still unfavorable--
are a little better. These have spreads of about 20 or 30 feet. One
very old oak, slowly dying and now shorn of most of its branches is
about 3 feet in diameter and must have had a spread of 50 or 60 feet at
one time. At present it has a dense growth about the trunk reaching up
about 10 or 15 feet and a few stubs of branches a foot or two in diameter
which are dying. It is growing out of a rocky bank and overhangs a
miniature glade bounded by an irregular circle of smaller oaks that
evidently grew from acorns of the old tree, as their position shows.
The interior of this glade has been left in its wild state and now
(February 1933) forms the principal haunt of the thrashers.
The glade
Before beginning building operations late in 1926 a small shack
8 feet by 10 feet was put up near the highest point of the property.