46 University of Califorma Publications in Zoology [ Vou. 17 
stant attempts to find and introduce some natural enemy of the more 
injurious insects is proof that where the natural control is lacking 
the most energy must be expended towards filling the need. 
It must be granted that the roadrunner, like all others under 
natural conditions, helps to maintain the balance of nature. And 
even if its work in the destruction of economically important insects 
is apparently of a less degree of importance, it should be remembered 
that the bird may be performing a service which we cannot measure, 
and that the systematic destruction of any of the natural enemies of 
insects may be instrumental in increasing the economic importance 
of that insect. 
It is only when the roadrunner comes in contact with settled 
communities that it can be said to be injurious, unless it be proved that 
the number of quail accessible to the hunter is materially reduced. 
Since most of the roadrunners are confined to desert regions far from 
the haunts of men, the total harm done is much smaller than would 
be the case with species more abundant in settled country. Then, 
too, both the possible damage and the potential good are greatly 
minimized by the fact that there is no concentration of individuals at 
any one time or place. The number of roadrunners in any one 
locality does not vary greatly and is always relatively small. Probably 
the maximum numbers per square mile do not exceed ten or twelve 
even in favorable localities. 
SUMMARY 
The roadrunner (Geococcyx californianus) is unique in many ways. 
Of particular interest are its breeding habits and especially food 
habits. It is doubtful if an investigation of the food habits of any 
other American bird could have yielded such unusual and interesting 
results. 
The investigation here reported upon included the analysis of 
eighty-four stomachs of roadrunners taken in southern California in 
1911 and 1912 and also a survey of all available literature relative to 
the food of the roadrunner in California. The stomachs became 
available as a result of the inquiry into the food habits of non-game 
birds instituted by the California Fish and Game Commission in 1911. 
The eighty-four stomachs represented birds taken every month of 
the year with the exception of March. The analysis of the stomach 
contents showed that practically 90 per cent (90.07 per cent) of the 
