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Comparable methods were used on these areas. Wetland habitat was classified and inventoried, and each year a record was made of those ponds that contained water. Breeding populations were estimated by direct counts and "beat outs" along roadside transects. Intensive nest searches were made to determine numbers of nests and their success, and broods were estimated from repeated searches of wetland areas. Hen success was estimated by the pair-brood ratio. Interpretation of the data is in many cases difficult because of biases, some of which were discussed by the authors, such as the difficulty in observing broods of dabbling ducks. Other biases, such as those described by Mayfield (1961), were not recognized at the time.

The most important characteristic of these pioneering studies was their longevity (Trauger and Stoudt 1978). The data gathered on these areas over a period of years furnished a base of knowledge upon which to build. The surveys were continued, at least in part, on some of the study areas, and new studies were occasionally initiated on the same areas to the present time, but most of the ground studies have been abandoned. A number of papers, exploring basic concepts in waterfowl biology and management, drew heavily on data derived from these study areas (Trauger and Stoudt 1978, Bailey 1981, Vickery and Nudds 1984).

Data from the Canadian study areas illustrate a dilemma. On the one hand, a few small study areas cannot possibly represent average conditions over the broad heterogeneous breeding habitat of ducks (Crissey 1984:262). On the other hand, data derived from numerous transects visited only once each year by aircraft cannot furnish the detailed information required to interpret data on breeding population and recruitment (Dzubin 1969a). Smith (1969:122) suggested the only obvious solution to the dilemma, "that men must be kept on intensive ground studies of waterfowl while others are engaged in extensive aerial surveys." Recently there has been a return to intensive ground studies (Greenwood et al. 1987), but these studies were of relatively short duration.