118 THE CONDOR Vol. XXIV 
small in comparison with the eight or ten miles which separated the large-hole 
from the small-hole trees as indicated above. 
However, observations of quite different character suggest rather strongly, 
though they do not prove, that the birds do at times move about for considerable 
distances. These observations I now present in brief, not, however, so much for 
their bearing upon the general economic problem, as it may rightly be called, of 
these woodpeckers in the Cuyamaca region. The problem concerns the abund- 
ance and distribution of the acorn crop from one year to another and in the 
same year. 
The black oak acorn crop was bountiful in 1921 in a small area on the south 
side of the lake, but was almost nothing in any of the other areas I was able to 
visit. Of the several hundred trees which J examined more or less carefully be- 
tween the lake and Julian and Pine Hills, a distance of about fifteen miles, not 
a single one was well loaded, and very few indeed bore any nuts at all so far as 
T could see. 
And quite similarly was it with both black and live oaks in the opposite di- 
rection from the lake; that is, toward Descanso distant about twelve miles. AI- 
though I devoted considerable time to inspecting many trees over several square 
miles, I saw surprisingly few nuts—though obviously the birds were more suc- 
cessful in finding them, in at least a few places, than I was, for as already shown 
they were able to garner in a good supply of live oak nuts for a few storage trees 
far from the lake. 
And this distribution of abundance of acorns certainly corresponded closely 
with the abundance of birds during the harvest period. I saw more birds on the 
square mile, more or less, at the lake where the acorn crop was good than on all 
the rest put together of the twenty or more square miles covered by my examina- 
tion. So far as I could determine there were something like two dozen birds at 
work in the area adjacent to our camp during the week of our sojourn there: 
and I surely did not see as large a number in all the rest of the area. It must 
be said, however, that my observations were much fuiler on the lake area than 
anywhere else. 
Now this distributional state of things, both as to acorns and birds, strongly 
suggests, as already hinted, that the birds had gathered into the small area of 
abundant crop from many miles around. And this suggestion has a clear bear- 
ing on the question of what birds drill the different sized holes. 
These observations and reflections on the general economics of our wood- 
pecker, fragmentary though they are, yet suffice to call attention to a research 
problem in natural psycho-biology which appeals to me not only as fascinating. 
but as promising rich returns for any one who would take it up and follow it up 
in dead earnest. The concatinated queries involved fairly strike one in the face 
so sharply do they stand out: and they seem numberless. 
Take those connected with the acorn crop, for example. What about its var- 
lation from year to vear, and from place to place in the same year? What vart 
do heat and cold, wetness and dryness. and other climatic factors play in the busi- 
ness? Are there really barren oak trees as well as barren fig trees, in nature? 
And what of the various nut moths that depend upon acorns for their exist- 
ence? How hard are they on acorn production and so upon the oak forests; and 
how much harder on acorns and oaks would the insects be if the woodpeckers 
were not in turn hard on the insects? . 
