The Cassin Kingbird 
and Bendire 1 adds, “Cassin’s Kingbird is neither as noisy nor as quarrel¬ 
some as the preceding species, and appears to be more of a mountain- 
loving bird and to nest at higher altitudes.” 
As to this last, we can only say that the rule does not appear to hold 
good in California. Cassin's Kingbird, at the nesting season, barely 
exceeds the upper limit of the Lower Sonoran faunal zone; and it is not 
even mentioned in the exhaustive reports on the San Jacinto and San 
Bernardino mountain regions. It is apparently of very irregular dis¬ 
tribution over the two California deserts, and in the lowlands of the 
San Diego-Santa Bar¬ 
bara region. I have 
found what I believe to 
be its local center of 
abundance in the sparse¬ 
ly timbered valley of 
the Estrella, in northern 
San Luis Obispo Coun¬ 
ty, and in the connecting 
tributaries. Here its 
close and all but invari¬ 
able association with 
T. verticalis is worthy of 
special notice. 
In this region of 
scattering oak trees and 
of stream beds lined with 
cottonwoods, both birds 
are exceedingly com¬ 
mon. As surely as a 
pair of oak trees 
boast some degree 
of isolation from 
their fellows, one 
will be occupied by 
a pair of Cassin 
Kingbirds and the 
other by a pair of 
Westerns. Or if 
the trees are only 
^ . . „ , . „ members of a ser- 
1 aken in ban Luis Obispo County 
ies, next door 
Photo by the A uthor . 
neighbors will be 
CASSIN KINGBIRD IN LIVE OAK _ 
860 
1 Life Histories, Vol. II., p. 250 
