of populations represented by the banded samples be determined, 
Information on the extent to which immature ducks are more likely 
to be shot than adults is necessary for tne determination of age 
ratios in the population from age ratios in the kill. 
The term relative recovery rate is used to express the degree to 
which one component in the population (in this case immatures) is more 
likely to be bagged than another component (adults). 
Relative recovery rates are calculated by dividing the direct 
recovery rate of immatures by the direct recovery rate of adults. 
A relative recovery rate of 1.50 indicates that the immature portion 
of a banded sample is 1-1/2 times as likely to be shot as the adult 
portion. This rate can be based on either all recoveries or on those 
from a particular harvest area. Relative recovery rates relate to 
the population at the time of banding and not to the individuals of 
each age group that are present in a given harvest area. 
The term relative recovery rate is used here instead of the 
term relative vulnerability rate as used by Bellrose et al. (1961) 
in order to restrict the latter term to a precise meaning; that 
characteristic of waterfowl such that when exposed to the same 
hunting pressure, one kind (immatures) will have a higher probability 
of being killed than will another kind (adults). The closer that the 
banding is to the time and place of recovery, the closer the recovery 
rates will reflect relative vulnerability, but as time passes, the 
selective kill or differential migration of an age group may change 
the age composition of the population available in an area. Thus, if 
a disproportionately large proportion of the immatures is harvested 
in a northern region, then in some southern region the recovery rate 
for immatures may become less than that for adults (and the relative 
recovery rate less than one) simply because fewer immatures have 
survived to reach the southern region. At the same time, additional 
age and experience may cause the immatures to become less vulnerable 
and further the decrease in the relative recovery rate. Bellrose et 
al. (1961) demonstrated how banding data could be used to estimate 
the extent to which immatures are more likely to be shot than adults, 
and discussed the factors which influence this difference, 
RESULTS IN 1959 AND 1960 
The numbers of mallards and black ducks banded and their direct 
recovery rates are shown in tables 1 and 2. Only birds banded during 
July, August, September, and October, prior to the hunting season in 
the State or Province of banding, are included. Ideally, pre-season 
banding should be completed before hunting begins in any area in 
which the banded birds might be shot. Thus, banding at stations in 
