(Ecology paper of 1934) and a couple of more years to demonstrate them
somewhat better (Errington and Hamerstrom, Research Bull. 201, 1936). After
then, of course, we were interested in seeing how well the patterns were
maintained, and I think it is most fortunate that we were; for some of the
Roff-points' showing up later proved to be important parts of the picture,
though we cannot even yet appraise their full significance.
It was only after we had groundwork enough to establish the reality
of the thresholds and inversities and to judge that b&nding wouldn't interfere
with our preliminary exploration thereof that we felt the time had come to
see what could be learned through banding and related techniques. Now,
twenty years after its inception, the study is taking us continually nearer
to an understanding of basic population mechanisms--and those of the greatest
importance from the standpoint of practical management--yet there is much
farther to go. I wouldn't say that, without it, modern conservation philosophy
would still be in the era of artificial stocking and "vermind control (which
hasn't entirely passed) but it has indeed meant advances that ordinary P-R
projects could never hope to achieve.
For that matter, just what practical information can one get out
of the usual run of P-R presentations of population data unless the problem
is exceptionally simple? Generally, how adequately can one appraise rates
of loss or gain, age ratios, movements, etc., without reference to such things
as thresholds of security or possible "cyclic" phases? I find the usual run
of P-R reports on short-term investigations of the most limited value, and,
in a lot of cases, they consist chiefly of undigested and practically indigesti-
ble figures.
The case histories of our long-term muskrat investigations zbow
parallelisms in some respects similar to those of Prairie du Sac, but I shall
refrain from outlining them here.
As Aldo says in his letter to rutermuth)a big need is to convince
state administrators that P-R is unbalanced and T   -1lad that he is mking
a start on the job.
Sincerely yours,
Paul L. Errington
Research Associate Professor
PLE:PK T

cc: Prof. Leopold