122 THE CONDOR Vol. XXIII 
The study of birds from a behavioristie standpoint has been relatively 
neglected, and those investigators who have given the matter some attention 
have usually gone to ‘one of two extremes: the field observers, being better 
naturalists than psychologists, have interpreted the behavior of birds in an 
extravagantly anthropomorphic fashion; and the experimentalists, being bet- 
ter psychologists than naturalists, have with amusing seriousness taken caged 
birds into the laboratory and assumed that they would there behave in normal 
fashion (ef. Porter, 1904 and 1906). What we need would seem to be a new 
science of ‘‘field psychology’’ which should combine in due proportions the - 
observational and experimental methods. 
The studies in behavior which follow* have been limited to the coast race 
of the Bush-tit (Psaltriparus mimmus ninimus), which occurs in considerable 
numbers on the Berkeley Campus, ranging over more or less definite areas of 
live oak and chaparral associations, or cultivated shrubbery. The birds are gre- 
garious during the greater part of the year, pairing off in February or March 
for the breeding season, and congregating into flocks again when the young 
are reared. The flock formation is relatively simple and loose, so that a much 
better opportunity is offered for analyzing flock-behavior than would be the 
case with birds manifesting a more complicated flock organization. More- 
over, observation has convinced me that the birds remain pretty much in the 
same locality all through the winter, so that the complication of a changing 
series of flocks is not introduced. 
The University Campus and neighboring hills and canyons have served as 
the field of operations. 
Three flocks of Bush-tits have frequented the territory under observation 
during the past winter (1920-21). The largest of these numbered about sev- 
enty individuals, the other two, respectively, twenty-five and twenty. These 
figures are based on averages, as the number of birds in a flock often varies 
in a puzzling manner, even while under actual observation. Such discrepan- 
cies are doubtless due in part to the difficulties involved in making accurate 
counts. The little creatures are in constant motion, popping in and out among 
the bushes, appearing and disappearing in a confusing manner, so that they 
can be successfully counted only as they occasionally straggle across an open 
space along the forage route. But allowing for a margin of probable error, 
the impression is still conveyed that there is an actual variation in the number 
of birds in a particular flock at different times, individual birds perhaps be- 
coming lost, or passing from one flock to another. 
These three flocks were observed on August 28 and again on October 16 
and subsequently, but not until the middle of the winter did the idea oceur 
to me that they might represent the entire Bush-tit population of the region 
under observation. Thereafter I made a practise of ‘‘rounding up’’ the Bush- 
tits in the locality from time to time, always beginning by scouring the campus 
thoroughly, then working up Strawberry Canyon. In every case I was able 
to locate the three flocks above mentioned. 
In addition to these periodic round-ups, I have made a practise of keeping 
record of every flock of Bush-tits seen on the campus, with time of day, general 
*NOTH.—This paper is chiefly an abridgement of a Master’s thesis written at the 
University of California during the current year. I am indebted to Professor Joseph 
Grinnell, under whose guidance this work was undertaken, for many helpful suggestions 
as to method, as well as much valuable information from his personal observations.— 
AUTHOR. 
