In a few species where banded adult birds are found dead 
during the nesting season by the general public, it may be possible 
to plot the distances at which they have been recovered from the 
original points of banding. This phenomenon should be explored for 
both robins and blue jays. 
A third type of correction has been applied to retrapping 
data. In this, the number annually trapped has been compared to a 
census on the study area, and a correction made for untrapped residues 
of banded birds in the population. S. H. Low (1933, 193) has thus 
converted return data into survival data for tree swallows nesting on 
Cape Cod, and Leopold, Sperry, Feeney, and Catenheusen (193) and Buss 
(1946) have analyzed winter trapping results for ring-necked pheasants 
in Wisconsin. The validity of the correction factor here depends in 
part on local landscape and land-use conditions that permit the censused 
population to be identified as the sample being trapped. It also depends 
on the assumption that the banded birds always return to the study area. 
Accuracy of bird-banding 
The system of bird banding has so long been a valuable source 
of information to ornithologists that ordinary skepticism regarding its 
results seems almost out of place at this time. The program is known 
to work; the question is, how accurately? 
Issuance of bands.--From 1922 to 197 the U. S. Government 
has. issued about five million bird bands. Of these, 10,000 (numbers 
BO67000 to B677000) are known to have been issued in duplicate and 
presumably used in the field. This is an overall error of 0.2 per cent. 
Retrapping by banders.--Since I made no studies of the survival 
of birds based on retrap work by banders, I did not appraise the accuracy 
of this type of research. When a bander retraps birds he has previously 
banded, perhaps only an eyewitness can check the carefulness of his work. 
When he reports the trapping of a bird ringed by another bander, the 
Fish and Wildlife Service has an opportunity to compare his report of 
the species and sex with that of the original bander. Discrepancies 
between such reports were fairly frequently discovered by Mrs. Lois 
Horn, of the Fish and Wildlife Service staff, during the time I worked 
at Patuxent. In the case of one veteran duck bander, 7 out of 8 "foreign" 
recoveries he reported in 1946-7 were either spurious numbers or credited 
to a different species by other ornithologists. 
Banders' schedules.--Official forms (or schedules) are used by 
banders to report their work to the government. On the whole, the prepa- 
ration of these seems to be good, the more inadequate record-keepers 
having been quickly "weeded out" through revocation of their banding 
permits. (A large part of one clerk's time in 196-7 was still being 
spent, however, in clarifying the schedules of banders who should have 
been dropped years ago.) One regrettable failure of banders should be 
mentioned. This is the tendency to omit age and sex in their reports, 
18 
