the more useful index of habitat becaOse May ponds often go dry by July; breeding 

 waterfowl are forced to move elsewhere when this happens. Thus the best index 

 of available habitat is the number of July ponds. Extensive bird counts 

 established the number of adult ducks returning to the prairie potholes each 

 spring as well as the size of the recruitment class for the 1955-1958 period. 

 The marginal physical product of prairie potholes was established from the 

 estimated coefficient for the number of ponds in a regression model in which 

 the size of the annual recruitment class was the dependent variable. The size 

 of the adult population was the other independent variable in this multivariate 

 regression model . 



Waterfowl breeding habitat has been declining rapidly during the postwar 

 years. In 1955 there were 5 million July ponds; in 1968 there were only 850,000 

 July ponds. The estimated marginal physical product of i pond was 2.2 birds; 

 since the estimated' willingness-to-pay for a bagged waterfowl was $3.29 (1974 

 dollars), the estimated marginal value product of a Canadian prairie pothole was 

 $8.88. The cost of an annual easement fee for a Canadian prairie pothole was 

 estimated to be $4.73 for all Canada in 1974 dollars. Using this cost and output 

 data, Hammack and Brown estimate that the socially optimal number of prairie 

 potholes is between 5 and 20 times the historical average. The historical 

 average is the average number of July ponds for the 1961-1968 period, 1.3 

 million. 



11. Gupta, T.R., and J.H. Foster. 1975. Economic cri'teria for freshwater 

 wetland policy in Massachusetts. American Journal of Agricultural 

 Economics 57(l):40-45. 



The authors present some original techniques for estimating benefits 

 conferred by various functions performed by Massachusetts wetlands. The socially 

 beneficial functions include wildlife habitat provision, visual aesthetic 

 benefits, groundwater recharge (water supply), and flood prevention and 

 amelioration. The most interesting valuation procedures are those for wildlife 

 habitat provision and visual aesthetic amenity values. To estimate the benefits 

 conferred by wildlife production, Gupta and Foster analyzed the prices paid for 

 wetlands by the Massachusetts Division of Fisheries and Game for more than 8,000 

 acres bought during 1969-1971, to estimate per acre benefits conferred by these 

 land parcels. 



The five highest prices paid for wetland parcels ranged from $584 to $2,387 

 per acre. Thus Gupta and Foster concluded that the capital i'zed value of per acre 

 wildlife habitat provision by wetlands was the most representative price paid 

 for these land parcels; they chose $1,200 per acre as the representative price 

 of the wetlands producing the highest per acre wildlife production benefits. 

 Thus $1,200 is, according to this methodology, the capitalized wildlife benefits 

 provided by the wetlands that are most productive with respect to this particular 

 function. After adding in an appropriate figure ($100) for the cost of 

 operation, Gupta and Foster convert the $1,300 capitalized value into a $70 per 

 annum net benefits flow by multiplying by a 5.375% discount rate. The valuation 

 methodology was extended by Gupta and Foster to encompass wetlands with varying 

 degrees of productivity with respect to wildlife habitat provision. They 

 accomplish this by establishing a point scoring system for wildlife habitat 



18 



