04-09-2007 Council Agenda - Laserfiche WebLink

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1997) but there has been no research on the population control efficacy. Christens et al. 1995, Christens 2001, and Cummings et al. 1997 investigated the effectiveness of egg oiling. The spraying of the eggs with mineral oil killed nearly 100% of the embryos, but the actual or potential (through modeling, c.f. Cooper and Keefe 1997) population impacts were not measured. Schmutz et al. (1997) concluded that adult goose survival rather than variations in reproduction were the primary determinant of population change. In 1998, the Michigan DNR in cooperation with the Humane Society of the United States initiated a major egg removal study (Gormley and Luukkonen 2000, Gormley et al. 2001). This program utilized volunteers to locate nests and replaced clutches with wooden eggs to prevent renesting (c.f. Cooper 1978). The wooden eggs were then removed to limit extended nest attentiveness (c.f. Cooper 1978, Cooper 2001a). While 1,390, 2,309, and 3,875 eggs were removed from 1998 to 2000 respectively (Gormley et al. 2001), the population impact was not measured or modeled. In fact, Gormley and Luukkonen (2000:7) concluded, without presenting data, that "It is unlikely egg removal will have a long -term effect on regional goose demographics." Cooper and Keefe (1997) recorded the time and cost of locating and removing 97% of the eggs from three large ( >20 ha) Twin Cities Metropolitan Area wetlands during the 1990 -96 period. Egg removal was 4X more expensive and population modeling indicated that it was 25% as effective as summer removal of flightless adults and young. The time spent searching for nests was calculated from search start and stop times and the time spent locating and removing eggs (2.6 hr /egg) was computed. The drawback of this approach is it does not permit estimation of the effort needed to locate a given proportion of the nests, for example 50%, 75 %, etc. Cooper and Keefe's (1997) data are also not representative of the efficacy of egg removal in habitats where nest detection is easier, e.g., islands, small wetlands, etc. In 1998, the nest search data recording was modified so that the effort expended to find each additional nest could be calculated, thus allowing the computation of a diminishing returns function for the large wetland nest searches. The proposed study would expand the TCMA egg removal research to island nesting (Lake of the Isles, Moore Lake, Battle Creek, Normandale, etc.) and small ( <20 ha) wetlands locations. Diminishing returns functions will be developed for 2