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Breeding Population Inventories and Measures of Recruitment

VII. The Future

Dzubin (1969a:225) stated that "there are no published, standardized methods recognized to enumerate indicated duck pairs nor to estimate pair numbers accurately from direct count data." Certainly, this is still true for estimates of breeding pairs and even more so for estimates of recruitment. Many of the recommendations that Dzubin made are not being heeded today. Unfortunately, many research investigations and all operational surveys lack the resources to conduct the repeated surveys that Dzubin considered necessary for determining the proper timing of surveys for each species and for correcting counts for unbalanced sex ratios. There remains a lack of consistency among studies in the methodology used for estimating breeding populations and recruitment. Thus, comparing results from different studies or examining long-term trends in recruitment is difficult. Perhaps even more disturbing is the current lack of long-term data from carefully conducted field studies.

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