of the waterfowl population (FWS 1950), but to the northeastern 
seaboard gunner the black is all important. In New England it makes 
up nearly half the annual bag. 
Of major importance in present-day management is a compre- 
hensive knowledge of the origins, destinations, and routes of water- 
fowl. Although the flight north in the spring has some significance, 
it is the return flight in the fall that counts most. This is the 
flight which commands the attention of the duck hunter, who wants to 
harvest his share, and of the technician and administrator who have 
determined what the annual take should be. 
Data Used_and Qualification of Terms 
This report is primarily an analysis of migration based on 
banding data. Therefore, at the outset it is desirable to define the 
data used and discuss the more important factors or biases involved. 
A discussion of the man-made and natural influences on the continental 
migration or movements of the black duck is important as a background 
for what follows. 
The data used are the records of fall shooting recoveries 
of black ducks that were banded at a series of points in the breeding 
and wintering ranges and along migration routes. All records of 
shooting recoveries (total 15,481) on file at the Patuxent Research 
Refuge, Laurel, Maryland have been analyzed. These records cover the 
period from the beginning of the black-duck banding, in 1918, through 
January 1951. 
Considering first the newly banded population at a particular 
point on the breeding grounds, the question arises: Just what does this 
banded population actually represent? Obviously, flightless juveniles 
banded during the summer are representative of birds raised on that 
particular marsh. They may be representative also of blacks raised on 
nearby marshes and conceivably may even typify populations from a much 
wider area covering an important geographic region. We know little of 
the geographic limits of areas producing black ducks with similar 
migration habits, nor do we yet have an accurate measure of production 
in much of the breeding range. Without this information, it is not 
possible to determine the number of blacks migrating from a particular 
banding locality and the importance of the bands from one location as 
compared witn those from another. For example, an equal number of 
birds might be banded on the breeding grounds at area A and at area B. 
Area A is extensive and supplies 10 times as many birds to the flyway 
as does area B. Recoveries from the bandings at A should be given 10 
times the value of those bandings at B. Since we do not have this in- 
formation, we cannot properly evaluate the data in comparing the two 
areas. 
Ou 
