The Wisconsin DNR proposes to delist wolves as neither state endangered or threatened when a late winter count of 250 wolves are achieved outside of Native American reservations in the state. At the delisted level, landowner control on nuisance or problem wolves can occur, and control can be expanded for law-enforcement officers. The state population management goal would be a late winter count of 350 outside of Native American reservations. At the management goal, proactive depredation control can be authorized.
The Wisconsin Wolf Advisory Committee spent a great deal of time developing the delisting level and establishing a population management goal. Four major factors were considered in the development of the population goals:
The U.S. Fish and Wildlife Service (1992) Recovery Plan for wolves in the eastern U.S. recommended maintaining a minimum of 100 wolves in Wisconsin and Michigan to federally delist wolves in the region. Since the Wisconsin - Michigan population was located within 100 miles of the much larger Minnesota population (2450 wolves in 1998), 100 wolves was considered adequate for maintaining a regional viable population. The same plan recommended that if a second wolf population in the eastern U.S. was more than 100 miles from the Minnesota wolf population, it should consist of at least 200 wolves.
Therefore, 100 wolves in Wisconsin and Michigan represents the bare minimum level at which federal delisting can be considered for the region. The wolf population in Wisconsin needs to avoid approaching this level to prevent wolves from becoming relisted as Federally Endangered or Threatened.
A second concern was an assessment of the potential habitat base in Wisconsin. Studies done in Wisconsin using a Geographic Information System (GIS) with known pack territories, showed that 5812 mi2 of land had a high probability of being settled by wolf packs (Mladenoff et. al. 1995, Appendix C). As many as 300 to 500 wolves could occur on the most suitable habitat at full occupancy (Mladenoff et. al. 1997, Appendix C). If wolves also occupied secondary or marginal habitat, possibly 500 to 800 wolves could occur in the state. On the other hand, if wolves are unable to fully occupy the most suitable habitat, and few occupy marginal habitat, the potential population could be considerably less than 500. Based on this assessment, 500 wolves occurring on about 6000 mi2 of suitable habitat seemed to be a reasonable estimate of the potential carrying capacity of wolves in Wisconsin. Therefore, in the first draft of the wolf plan, an upper limit of 500 wolves was established for Wisconsin. Because of concerns expressed by many on the first draft, the figure was modified to a management goal of 350. The management goal represented the minimum level at which a full array of population control activities could occur including pro-active depredation control and the possibility of public harvest.
Long term viability of the Wisconsin wolf population was a third concern addressed by the Wisconsin Wolf Advisory Committee. Fritts and Carbyn (1995) conducted an extensive review of wolf population viability analysis, and determined that although no one really knows the minimum viable population of wolves, it appears that 100 or more wolves would be needed to maintain viability in isolation. Others have suggested that as many as 500 wolves may be necessary for long-term viability in isolation (Soulé 1980). Haight et. al. (1998) determined by modeling, that 16 wolf territories could maintain long-term survival in disjunct populations if immigration was adequate and portions of the population are highly protected; Haight et. al. (1998) considered packs to average 4-8 wolves, or an overall average of about 6 wolves. Thus, the 16 territories would represent about 96 wolves, and with an average 15% loners would consist of about 110 wolves. Therefore, Haight et. al. (1998) would further support the idea that about 100 wolves could maintain viability if adequately connected to other populations. Thus, the literature seemed to suggest that about 100 wolves would be adequate if highly connected, but if isolated, populations may need to be at levels of 200 to 500 wolves to maintain long-term viability.
We further examined population viability analysis by conducting analysis of the Wisconsin population (Appendix B). Population viability analysis provides a useful way of looking at the dynamics of a wildlife population, but needs to be cautiously interpreted and should not be used by itself to set management goals (Bessinger and Westphal 1998, Reed et. al. 1998). When examining varying levels of reproduction, environmental variability, and catastrophes, risk of extinction or relisting as endangered were often fairly high at 100 animals. But at populations of 200 or more animals, risk of extinction or relisting declined drastically, and the risks for 300 to 500 animals were similar and relatively low for most categories. The analysis was done on an isolated population to provide a conservative estimate of animals needed for long-term viability if exchange of wolves among the Great Lakes population declines in the future. Based on this analysis, a population between 200 to 300 seemed appropriate for delisting wolves in Wisconsin.
The fourth area of concern that needed to be addressed in developing a population goal is the social intolerance of wolves that may develop at a high population level. Habitat modeling, literature reviews, and population viability analysis provide somewhat systematic means for determining viable levels and potential populations for state wolves, but determining levels of social tolerance is more subjective. The Wolf Advisory Committee settled on a management goal of 350 wolves as a reasonable first attempt at assessment of social tolerance. The 350 level was intended to be the minimum level at which proactive control and public harvest would occur. This management goal falls about half way between the delisting level (250 wolves) and the perceived biological carrying capacity (500 wolves) for the state. During the review of the second draft of the wolf plan, of persons commenting on the population goal, 38% supported the goal, 38% felt it was too low, and 24% felt it was too high. Therefore, the goal seemed to be a reasonable compromise between population capacity, minimum level of viability, and public acceptance.
Delisting and relisting criteria for Wisconsin wolves are shown in table 2 and figure 7. Table 2 also illustrates federal listing criteria. State reclassification from endangered to threatened occured in 1999. The state delisting level may be achieved within 2 more years and the management goal could be achieved in 5 years (Figure 7). Federal criteria for downlisting to threatened were achieved in 1997 and the downlisting process may be finalized in 2000. The federal delisting process will probably begin in 2000 and should be completed sometime in 2001 or 2002.
| Table 2: Wisconsin Wolf Listing/Delisting Criteria | ||
| Wisconsin Wolf Population is: | State Listing | Federal Listing |
| less than 80 | Endangered | Endangered |
| 80 or more for 3 yrs. | Threatened | Threatened |
| 100 plus for five years Wisconsin and Michigan | Threatened | Delisted |
| 250 wolves for 1 year. | Delisted | Delisted |
| Decline to less than 250 for 3 yrs. | Reclassify as Threatened | Delisted |
| Decline to less than 80 for 1 yr. | Reclassify as Endangered | Not Specified |
Some management proposed under state delisting will not be possible until federal delisting also occurs. Federal reclassification from endangered to threatened will allow DNR and USDA-WS to kill wolves causing depredation to livestock and pets. Total federal delisting will be required before the following can occur: lethal control by landowners; and proactive control by government trappers and public harvest.