Biological Problems With Delisting and Hunting Wolves
 
On the advice of his biologists, Secretary of the Interior Ken Salazar has decided to remove wolves from the endangered species list throughout most of the northern Rocky Mountains.         Delisting means that individual states will assume management responsibility and can allow wolves to be hunted.  Agency biologists and other proponents of delisting argue that there are no worries about the population’s genetic variation and that the population will therefore remain viable, i.e., persist overall albeit at some smaller size, in the face of regulated state hunting. Opponents argue that the Interior Department has not yet shown there is enough genetic mixing for the population to be viable in the face of hunting, that wolf numbers could end up declining much more sharply than expected.  The Interior Department has replied that it will monitor the situation carefully, to ensure that wolf numbers will not drop below certain levels.
 
The underlying problem with the arguments on both sides is that ultimately they place too much emphasis on numbers of wolves and their population and not enough on the biological features and primary functional units that most define this species and set it apart.  This is also the fundamental biological flaw in the thinking behind delisting wolves of the western Great Lakes region and in allowing heavy killing of wolves across the North in general.    
 
Routine public ground hunting (without direct use of airplanes, helicopters, snowmobiles, etc.) is unlikely to suppress numbers as in the worst-case scenarios being envisioned particularly for the northern Rockies and in some cases might even temporarily result in higher numbers, because of social fragmentation.  However, any substantial ongoing exploitation of a species with a long evolutionary history of and complex adaptations for cooperative breeding and cooperative hunting, but with no comparable history of being exploited, stands to degrade its biology in other important ways.
 
As noted in previous blog entries, the biology of organisms, societies, and systems is described by behavior, patterns, processes, and much more, at multiple scales and across scales, not just by the number of individuals present or how fast they bounce back from losses (Haber 1996, 2007).  The number of individuals present at any given time, i.e., abundance, is more of a manifestation of the biology - of the behavior, patterns, and processes, etc. - and, for wolves, not a very sensitive manifestation.  
 
Genomes and patterns of genetic variation across populations and within and between primary functional units (e.g., families, societies) are of central importance in defining the biology of a species.  But so, too, is the large amount of information that is transmitted across generations via learning, especially in ultra-social species like the wolf that feature prolonged dependency of the young, cooperative breeding, and cooperative hunting.  Ultimately such behaviors – or predispositions – are encoded in the genome.  However, simply preserving the genome is not enough to ensure their expression in the face of hunting or trapping.
 
Wolf numbers often rebound from public hunting, trapping, and heavier agency killing, at least in the short term, without reflecting anything obvious to most observers about other impacts. Nonetheless, there is evidence (Haber 1996) of lingering impacts (after numerical recoveries) on the social structure and other behavior, hunting patterns, distribution (including territories), genetic variations, and mortality patterns of survivors and recolonizers.  These impacts begin showing up by the time annual areawide hunting and trapping losses have reached 15-20 percent (Haber 1996), i.e., at rates below what usually would be needed to offset annual reproduction.
 
The primary functional units of wolf biology are families and extended families (“packs”) featuring among the most sophisticated forms of cooperation known for vertebrates (Haber 1977, 1996, 2007; see also other blog entries on this Web site).  A relative few of the oldest, experienced wolves, especially the primary (“alpha”) breeders, typically assume the key roles. Because these core adults commonly stand out near the forefront as leaders or with other assertive behavior, they are disproportionately vulnerable to ground and aerial shooting. Although young, inexperienced wolves generally sustain most of the trapping losses, the behavior of the core adults leaves them vulnerable to this killing method as well.  For example, high-ranking adults commonly try to help other family members who get caught and in the process risk getting caught in nearby traps and snares themselves.  
 
The assertive behavior of core adults also means that they are often the wolves most likely to be killed or injured during natural intergroup conflicts.  However, the frequency of these conflicts can vary dramatically with foraging variations; thus the conflicts constitute a much less significant source of mortality in some large areas than in others (Haber 2007).    
 
Biologists often equate the well known 30-40 percent or higher average annual areawide losses that wolves sustain under natural conditions to losses from hunting, trapping, and agency killing programs, in terms of their impacts.  They commonly argue or imply that hunting, trapping, and other killing merely replace the natural losses and are therefore of little biological consequence. A common variant of the argument is that wolves should be able to sustain higher harvest rates than ungulates (e.g., elk, moose, caribou) because they have higher reproductive rates.
 
This thinking overlooks two important points: (a), the natural losses consist largely of pups and subadults, who die and disperse; (b), the natural losses, including of key adults, typically vary in ways that are related to social and food variables, such that they may compensate for changes in group sizes and prey availability and thereby enhance the ability of groups to persist (Haber 1977, 1999, 2007; Mech et al 1998).
 
In contrast, hunting, trapping, and other human-caused losses across large areas are more likely (above) to include adults with key roles in maintaining the integrity of groups and determining how they function but are unlikely to vary in adaptive ways (spatially or temporally). This probably explains why hunting and trapping impacts begin showing up at loss rates well below the natural average annual areawide rates (at 15-20% vs. 30-40%+).
 
Most of the wolf behavior and wolf-related ecological patterns and processes that prevail in the prolonged absence of hunting, trapping, and other human killing are adaptive, including the foraging variations that result in area-to-area differences in the frequency of intergroup conflicts. Shredding and sometimes even temporarily distorting them via hunting and other killing is therefore likely to diminish, e.g., simplify, something about the species, its groups, its interactions with prey, and/or broader system interactions.  
 
When this happens, it amounts to an important biological loss even if wolves recolonize an area or their numbers have not yet declined much.  As I pointed out in Haber (1996) regarding wolves and Darimont et al (2009) and Stenseth and Dunlop (2009) observed for hunting and fishing in general, it should be assumed that hunting- and fishing-induced evolution might occur with unforeseen biological consequences that could be difficult or impossible to reverse. For species like wolves with little or no significant evolutionary history of being exploited, selective pressures induced by hunting and other human killing are likely to act in the opposite direction of those induced by natural mortality.
 
Complex systems such as wolf societies can be expected to behave in counterintuitive, nonlinear ways, including with lags and discontinuities.  This provides all the more reason for not assuming that all is well simply because there has been a numerical “recovery” (or series of annual recoveries) from human killing, particularly in the case of a relatively new wolf population. State management plans scheduled to take effect with federal delisting will allow sufficient ongoing killing to risk changes in the fundamental behavior that sets wolves apart as a species, including by fragmenting/simplifying and otherwise diminishing the primary functional units, if not an eventual longer-term decline in numbers.  The comments in the third paragraph of the right column on page 1075 of Haber (1996) might be the most important of all to consider. Endangerment can happen via diminished numbers of individuals but also by diminishing the numbers of individuals and groups behaving in ways consistent with the species’ natural direction of evolution.
 
While I disagree with proponents of delisting that there is a biological rationale for allowing routine hunting and trapping of this species (Haber 1996), I agree that there will be a need to remove problem wolves now and then, most commonly when wolves begin moving into areas of heavy, incompatible human use.  The present legal status of northern Rocky Mountains and western Great Lakes wolves already allows officials to take these measures; it is not necessary to delist them for this purpose.  Delisting would result in widespread, indiscriminate hunting impacts on many established groups of wolves in areas where there are no major conflicts with people and the wolves are essentially controlling their own numbers (group sizes and number of groups), as wolves do under natural or near natural conditions (Haber 1977, 1999, 2007; Mech et al 1998; Meier et al 2006).
 
Literature cited
Darimont, C.T., S.M. Carlson, M.T. Kinnison, P.C. Paquet, T.E. Reimchen, and C.C. Wilmers. 2009.  Human predators outpace other agents of trait change.  Proceedings of the National Academy of Sciences 106: 952-954.
Haber, G.C. 1977. Socio-ecological dynamics of wolves and prey in a subarctic ecosystem.
Ph.D. dissertation, Univ. of British Columbia.  817 pp.
Haber, G.C. 1996. Biological, conservation, and ethical implications of exploiting and controlling wolves.  Conservation Biology 10: 1068-1081.  Available on Reports page of this Web site.
Haber, G.C. 1999. A selective view of wolf ecology.  Conservation Biology 13: 460-461.
Reports page.
Haber, G.C. 2007.  Wolf foraging and related social variations in Denali National Park.
Alaska Park Science 6(2): 73-77.  Reports2 page.
Mech, L.D., L.G. Adams, T.J. Meier, J.W. Burch, and B.W. Dale. 1998.  The wolves of Denali.
Univ. of Minnesota Press, Minneapolis. 227 pp.
Meier, T., J. Burch, and L. Adams. 2006.  Tracking the movements of Denali’s wolves.
Alaska Park Science 5(1): 30-35.
Stenseth, N.C. and E.S. Dunlop. 2009.  Unnatural selection.  Nature 457: 803-804.  
 
 
Mar 19, 2009