154 THE CONDOR Vol. XXIV 
the result of stimulus rather than tutelage,—induced parallelism, rather than 
true mimesis? We have all heard bird notes that resembled those of insects 
which were vocal at the same time and place, but we do not suggest that one 
learned from the other! The sound of the rattlesnake has no connection with 
Fig. 35. NESTLING MOCKER; SAN CLEMENTE ISLAND, 
that of the ‘‘rattle-weed’’ save in similarity, and sometimes fortuitous propin- 
quity. Admit that the insect vocalization might activate the Grasshopper 
Sparrow, the weed might activate the rattler—then, by the same token, the 
Killdeer might activate, but not teach, the mockingbird. We have all seen a 
frisky calf set a sedate plow horse to gamboling in the same pasture, yet no 
