The reliability of information based upon banded birds bagged which are reported depends upon the extent to which the following conditions are met: ....1. The reported ratio is the same between years with the same areas of interest....2. The reported ratio is essentially the same between different areas of interest....3. The reported ratio is known for each area of interest....If the first two conditions are met, the banded birds bagged which are reported will always have the same relationship to total banded birds which are bagged. Under these conditions the reported ratio is substantially a constant, and, once it is determined, the investigator could use this ratio for estimating the total number of banded birds bagged. Currently, the necessary conditions leading to the above relationships are not being met, and the situation with respect to reported ratios is as follows:...1. The reported ratio is different between years within the same area of interest. This situation is common but its limit is unknown....2. The reported ratio is different within the same year between different areas of interest. This situation is very common but its limit is unknown. ...3. The reported ratio is different between waterfowl species. The difference between several species has been demonstrated. ....4. The reported ratio is not known for each area of interest. Because of item 2 above, the potential number for different reported ratios is as large as the number of areas of interest. The large number coupled with their lack of constancy (item 1 above) has created a very difficult problem relative to determining reported ratios for all areas of interest....A number of activities which contribute to increased variability in the proportion of bands taken that are reported include:....(1) band reports from those conservation agency employees who make particular efforts to report all the bands they note at checking stations, or in other special bandcollecting programs in which efforts vary from area to area and from year to year; ...(2) publicity campaigns, which are sporadic and not uniform: efforts of writers of some sports columns have had serious effects because of their strong influence..... (3) reward-band programs, which are difficult to administer and finance. and which are almost certain to have variable effects in different areas and different years;....(4) lucky-band contests which have the disadvantages of both (1) and (2). There is some evidence, also, that color-marking programs may have an effect on band returns, and it is suggested that these effects be evaluated.....In view of the above, the chances appear good for obtaining a substantially constant reported ratio in the same area of reference between years by removing these activities. It is believed that the reliability of information based upon banded birds bagged which are reported will be increased in proportion to the degree to which the above practices are decreased.
Additional publication details
Problems associated with practices that increase the reported recoveries of waterfowl bands