Using Waterfowl Harvest Data to Investigate Efficacy of Non- toxic Shot Regulations

The Illinois Waterfowl Hunter Harvest Survey has been collecting waterfowl harvest and crippling data from hunters since 1981. Lead shot was banned for waterfowl hunting in Illinois beginning with the 1994 waterfowl season. We employed time series analysis to investigate efficacy of non-toxic (“steel shot”) regulations on waterfowl crippling rates for ducks and geese among Illinois hunters across the 33 years of waterfowl harvest data. Crippling trends prior to 1994 (R2 = -0.356) suggest the same trend in decline as that from 1994 to the present (R2 = -0.353); however, number of crippled ducks was greater prior to the lead shot ban. Crippled ducks per 100 ducks bagged showed a steady trend prior to the ban (R2 = 0.001) and declined after the ban was in place (R2 = -0.617) with number of crippled ducks greater prior to 1994. Standardizing crippled ducks per hunter per day produced differing trends: Cripples were greater and trend line for decrease lower (R2 = -0.153) prior to the ban, and trend for crippled ducks (R2 = -0.540) declined following the ban. Trends for geese showed crippled geese per year increasing (R2 = 0.478) prior to the ban, and declining afterwards (R2 = -0.178). Trends for crippled geese per 100 bagged were similar to ducks: R2 = 0.0003 prior to the ban and R2 = 0.-535 after it was in place. The trend for crippled geese per hunter per day was increasing prior to the ban (R2 = 0.142) and declined afterwards (R2 = 0.331). Discussion will focus of the effectiveness of the lead shot ban on waterfowl crippling in Illinois and use of harvest data to denote trends in regulatory effects.