Trend in Population Size

The remarkably high intrinsic population growth rate makes wolves one of the world’s most prolific and resilient vertebrates. This life history fact underlies much cause for optimism for wolf recovery globally. For Scandinavian wolves, the primary risks to continued population growth are indiscriminate killing by humans (especially poaching) and – to a much less extent – inbreeding depression if the population remains small and isolated. The trend in population size over time integrates how well the population is dealing with stressors on vital rates. Thus, a stable or increasing average stochastic growth rate is an obvious FRP criteria, and one that is relatively easily monitored in the field using methods already developed by Scandinavian wolf researchers. Appendix I has some specific thoughts on analysis of trend using the count data. 2) Connectivity With the Functional and Greater Metapopulation

As described above, the Scandinavian wolf population can be considered a

subpopulation of a larger greater metapopulation that extends from Norway to the eastern edge of European Russia and south to Poland and northern Ukraine; functionally, dispersers are most likely to arise from the Finland / Karelian region. While Sweden can only legally manage its portion of the Scandinavian wolf subpopulation, metapopulation viability and connectivity

19 between the subpopulations remains a crucial component of both short and long-term viability of wolves in Sweden.

The benefit of connectivity is especially obvious for Swedish wolves because of its high profile history, with population growth increasing dramatically after the arrival of the single male immigrant to the tiny (<10) Scandinavian population in 1990 (Vila et al. 2003). More broadly, wolves in general remain perhaps the best ‘poster child’ species for the concept of genetic and demographic rescue, whereby immigration breaks inbreeding depression, provides new mating opportunities, and steers small populations away from threats of stochastic

extinction. For example, evidence for genetic rescue exists in North America for Mexican wolves (Hedrick and Fredrickson 2010, Rocky Mountain wolves (vonHoldt et al. 2010, Hebblewhite et al. 2010), and wolves on the island of Isle Royale National Park (Adams et al. 2011).

Of course, genetic rescue to minimize or erase the demographic consequences of inbreeding depression can only work if the local conditions remain favorable to stationary or increasing population growth. It is instructive that for all of the cases of genetic rescue in wolves mentioned above (Scandinavian, Mexican, Rocky Mountain, and Isle Royale), the consistent conclusion is that demographic gains from genetic rescue can be completely overwhelmed by lack of human tolerance or drastic change in habitat (Mills 2013: 171).

In sum, we believe that after controlling poaching the single most important

management action to sustain Scandinavian wolves is to nurture natural connectivity into the Scandinavian population from other regions of the functional metapopulation. Although the challenges are daunting, the benefits include eliminating inbreeding depression, decreasing local stochastic extinction probabilities, increasing resilience to mortality such as hunting, and fostering a sufficiently large metapopulation to undergo adaptive changes in the future. Next we address the levels of connectivity and mode of immigration.

2a) Required Level of Connectivity

Based on intense consideration of specific criteria for metapopulation connectivity, some reasonable thresholds have emerged for Scandinavian wolves. We conclude that at least 1 or more effective (reproducing) immigrants from elsewhere in the greater metapopulation into the

Scandinavian population per wolf generation (5 years) would be sufficient for FRP status.

Importantly, this amount of immigration is, in this case, more of an optimum than a minimum; that is, negative effects may arise not only from much less immigration, but also from much more. The negative effects of ‘too much’ connectivity have not received much attention in the Scandinavian wolf literature. Several factors underlie the potential negative effects of too much connectivity. First, very high levels of gene flow will swamp local adaptation (Mills and Allendorf 1996); too much gene flow will therefore risk obviating the ability of Scandinavian wolves to respond via evolution to future environmental challenges. Second, high levels of gene flow may increase the risk of transmission of disease or breakdown in local social structure. Finally, the very high numbers sometimes suggested (eg 2-4 actual immigrants per year; Hansen et al. 2011) would not only create unnecessary strain on logistics and social acceptance but also force the undesirable option of needing to physically translocate animals from other populations or from captivity (addressed below).

20 Clearly, however, the maintenance of at least one naturally dispersing, effective

immigrant per five years from elsewhere in the metapopulation into the Scandinavian population will require hard work and deep dedication by policymakers.

2b) Achieving Connectivity Through Natural Versus Managed Translocations The challenges of sustaining immigration into the Scandinavian subpopulation inevitably raise the possibility of managed translocations based on physically moving individuals from wild or captive populations (eg Hansen et al. 2011). Although this ‘human assisted migration’ might seem a more logistically and politically feasible alternative than nurturing ‘natural’ immigration from elsewhere in the metapopulation, we urge extreme caution before considering such actions (see also Räikkönen et al. 2013). First, depending on where the animals come from, managed translocations could compromise local adaptation or break up coadapted gene complexes, leading to outbreeding depression (Edmands 2007); this concern will be exacerbated with captive animals, whose genomes can diverge quickly from wild animals due to rapid artificial selection to captivity. Second, manually transporting animals substantially increases the risk of disease transmission and its catastrophic

consequences. Third, pack structure and mating systems could be negatively affected by import of animals of arbitrary age or sex. Finally, and most importantly, managed translocations creates in the public an illusion of meaningful action to sustain a wild population when fundamentally the opposite is occurring. The use of frequent translocations to overcome anthropogenic dispersal barriers violates the notion of a self-sustaining population, and creates a ‘conservation reliant’ species (Scott et al. 2005) dependent on intense human management in perpetuity.