Dr. L. David Mech Wolf Biologist

1. THE DENCE LECTURE Dr. L. David Mech Wolf Biologist “A 50-year Career of Wolf Research” Friday, April 17, 2009 4:00 pm Marshall Auditorium Reception to follow Dr. Mech has studied wolves in Yellowstone Nat’l Park, Minnesota, Isle Royale, Alaska and Canada's High Arctic (80°N). These photos are of High Arctic wolves.

2. Summary here Habitat MAKES a difference! Non-lethal effects may be more important to wildlife management than lethal ones. May be able to manage impact of predation via habitat. Landscape of fear/opportunity may be the most valuable management tool in management AND conservation. Example?? Go to sheep presentation

3. So what do we have? • Habitat…Habitat….Habitat • Brings us back to the beginning: wildlife management is habitat management. • Not just measure landscape of fear, modify it! • All we talked about, food, reproduction, predation, population dynamics, energy flow…. All rooted in habitat.

4. Habitat is the medium in which energy is captured…or not. • So ecology is the play, habitat is the stage.

5. Wildlife management • Ok, covered the ecology part of the course, lets look at the management part. • First we will look at how we have been managing wildlife • Last we will look at how we should manage wildlife!

6. Chapters 13 and 14 • Deal with more practical aspects: counting animals (13) • Age structure (14) • Mostly techniques stuff which game agencies spend a lot of time doing! • Annual herd counts, flock censuses, etc. • If we have time, we will look into but…

7. Goal of wildlife management • Reasons for these is to aid in the REAL goal of wildlife management: how many can we kill! (wildlife harvesting, chap 19) • The harvest • The off take • The whatever you want to call it, • Human predation on selected wildlife species.

8. Second goal of wildlife management • Aside from trying to put more game in the bag and more fish in the creel. • Game agencies have a second goal of: • Keeping other species from getting OUR game! • “wildlife control” (chap 20)

9. Management in a nutshell • These two goals: more for us, less for them. • Have and continue to be the center focus of wildlife management in the U.S. • So we need to look at them and end up by asking if that is how it should be???

10. But first • Need to put current wildlife management in its context. • If we start from a point in time, theoretically can go in an infinite number of different directions. • Once wildlife management got started, why did it take the direction it did? • A little bit of history

11. A bit of history • Where does the basis for wildlife management come from? • When Europeans arrived, came to a continent “teeming” with wildlife. • Deer, waterfowl, turkeys, abundant and viewed as having no end.

12. In less than 300 years • First settlements in North America were around the 1600’s • In less than 300 years (late1800’s) our ancestors had devastated these “endless” wildlife populations. • The list of overuse and abuse is long and legendary, and in some cases is still growing.

13. Low points • Eastern region had rid itself of all large game except deer, and even these were nearly eliminated from many areas • The Midwest became the farm belt at the expense of wildlife numbers rivaling the plains of Africa • The western regions reduced and eliminated many wildlife populations: At one time in the state of Colorado there were 0.00000 deer!

14. But was this new?? • But even so, what continent had was a shadow of what existed before. • Mammoths, ground sloths, BIG animals and their predators. • One theory as to why disappeared was when other group of humans came. • Pleistocene overkill

15. Imitating first immigrants • The new immigrants were just doing what the first ones had done, only more effectively because of advanced technology. • Impact of earlier Americans limited by their technology • Now: guns vs arrows, horses vs feet • Steel saws vs stone hatchets, and the technology kept on growing!

16. Compounding factors • In Europe, socially, there existed few landowners: kings, lords, etc. • Owned the land AND the wildlife • Wildlife in a large area were private property of ONE person. • Predation rate low (illegal killing severely punished) • Game keepers cared for the wildlife (that the owner wanted).

17. Majority of the people • Had no use for wildlife because they could not benefit from it • Viewed as one of those privileges of the rich. • Now all of a sudden 100,000’s came to a land were wildlife was free for the taking!

18. A continental killing spree. • European immigrants, raised in a social environment where game were owned by the large landowners, responded like turning a wolf loose in a sheep pen! • It became our “right” to use wildlife as we saw fit. • Commercial hunters had the same social status as commercial fishermen still have today.

19. Double barreled • So added to an individual’s right and need to kill wildlife • The commercialization of hunting added the free enterprise aspect, except with a twist. • If supply was low and demand high, kill more because you will get more and they will then be worth more. • If supply was high and demand and price low, kill more to make up for the low price

20. And besides… • Wildlife populations were “endless”!

21. What was to be done? • Some began to realize that the killing could not continue. That some control had to be exerted. • Wildlife management was born as an attempt to control the slaughter. • Earliest “game laws” in the late 1600’s and 1700’s were attempts to limit our effectiveness as a predator.

22. Was that wildlife management? • One can argue that these early attempts at controlling the kill were not actually wildlife management as a collective effort to “manage” wildlife and certainly not a science! • Many argue the science of wildlife management got started in the 1920’s and 30’s

23. Aldo Leopold • argued that modern science and technology could be used to restore and improve wildlife habitat and thus produce abundant "crops" of ducks, deer, and other valued wild animals.

24. But what model should we use? • If your going to start something like wildlife management, usually creativity of ideas is limited by historical and cultural confines. • Trained in forestry (tree farming) • So with this the mold was struck: Wildlife were to be managed as livestock.

25. Talk the talk • The livestock model can be seen in most aspects of how we talk about wildlife. • Herd, flock • Harvestable surplus: Harvest!! • Sustainable yield • Carrying capacity. • Talking to a wildlife manager is like talking to a cattle rancher.

26. Set in motion • Within this paradigm we began to try and determine how many animals can we send to slaughter each year and still maintain the herd. • Little more difficult because: • 1) often don’t know how large the herd is. • 2) have limited control over the harvest. • Reason is because every hunter is a rancher!

27. But that is how it is, still… • So, you as potential managers need to be exposed to all this. • Will go through chapter 19 and pull out the information necessary to understand how wildlife managers attempt to control the harvest of wildlife species.

28. Central theme • Thru all of this runs one central theme regarding wildlife harvesting • Harvesting of wildlife must result in a sustainable yield that can be taken year after year without jeopardizing future yields. • Again, sound livestock ranching but true!

29. Idea of a sustainable yield • Strategy to achieve a sustainable yield is: • To harvest the population at the same rate as it can increase! • Example: If population is increasing by 20% per year, then you should be able to harvest around 20%/year! • This is a net rate of increase: after all factors figured in (e.g.various other mortality factors).

30. How do we achieve it? • Obviously sustainable yield levels are affected by factors not under direct control e.g. resource levels • So most important aspect (controllable) is the regulatory strategy (legal limits) used to set harvest levels. • Or basically, how do we actually control the harvest?

31. Fixed Quota harvest • Obviously various techniques can be used. • We will review them to see the philosophy and logistics behind them. • The first is the Fixed Quota Harvest strategy. • Will look at this one in detail to get feel for how they are developed

32. Fixed quota • Most unharvested populations have a rate of increase that averages zero! • So what is the sustainable yield? • The philosophy behind the fixed quota harvest is: • If you harvest a given number of individuals (fixed number) then you stimulate that population to increase by setting into motion a chain of events.

33. How is it done? • Based on the idea that IF you increase resource levels, a population will grow. • More food = more animals • The reason for this is because there are more of the resource PER animal. • So the key is increasing the amount of the resource per animal.

34. How is it done…cont. • Ok, so if increasing the level of resource increases per animal amount….. • Keeping resource level the same but DECREASING the number of animals will give the same result! • By removing individuals (the harvest), more food to go around, more food, greater fecundity/lower juvenile mortality and population increases back toward original level!!

35. But how many should we remove?? • In general the further the density is reduced, the higher the yield as a percentage of the population size. • That is, If you remove 50 % of the population and it “grows” back to original level, your yield would be higher than if you only removed 25%.

36. But is there a limit? • IF you do remove 50%, WILL it recover?? • Just how many can you remove? • Based on intrinsic rate of increase of the species. • Based on maximum fecundity, maximum survival, etc. • This is based on maximum resource levels!

37. Induced rate of increase here • So intrinsic rate of increase is based on maximum resource levels, fecundity, etc., which only occurs when population is at a minimum! • Any N greater than that, rate of increase decreases, eventually 0 at K • So any reduction we do, will result in an induced rate of increase < intrinsic

38. Some declining function • Induced rate of increase will be close to intrinsic at a minimum of N but decline as N increases. • So higher N, lower induced rate of increase. • Based on that, we need to determine what is the sustainable level we can harvest.

39. How do we calculate it? • First remember: we are attempting to imitate how a population would respond “naturally” without harvest • The idea is that below K, there is a natural induced rate of increase that will lead to a net recruitment of new individuals as population moves toward K.

40. Harvest replaces recruitment • So, IF population is reduced “naturally” to some level, recruitment then replaces this lose, if we harvest the same number of animals, we reduce N and expect recruitment to replace these animals. • Trying to mimic recruitment under natural conditions. • Harvest can be what will be replaced by this recruitment.

41. But how much recruitment will there be? • Since induced rate of increase is density dependent, the recruitment level will vary across densities. • At any given density it will be the result of the combination of induced rate of increase and density.

42. Bell curve • This can be envisioned as a bell shaped curve over the range of density up to K • At low N, low recruitment because of low numbers of reproducers • At high N, close to K so little recruitment because of environmental resistance. • In the middle somewhere it will peak. Net recruitment N K

43. Now change recruitment to harvest • IF we harvest back the population to a certain level, should expect a response similar to what we would predict naturally. • Sustainable yield any point along that line. Net recruitment or harvest N K

44. Rule of thumb • Best sustainable yields will be at intermediate densities, highest recruitment rates. • Example • Small harvest of large population, induced rate of increase small (large x small) 12 x 3 = 24 • Large harvest of population, induced rate of increase large but remaining population small (small x large) 3 x 12 =24 • Intermediate: 6 x 8 = 64

45. So…How do we calculate it? • Maximization problem: • Trying to maximize the absolute yield • Highest yield is at a density where the induced rate of increase multiplied by the density is maximum.

46. Looking for ideal sustained yield • If we set harvest at a given level (20) note that it intersects curve in two places. • Called sustained-yield pair.

47. So naturally • Naturally, a recruitment rate of 20 would be replaced either if the population had been reduced to 80 OR 20. • Means we could harvest back to 20 if we want??

48. Not necessarily • To harvest these 20 is harder at lower density • Also it is unstable and any reduction below the lower density would lead to overharvest and population decline because recruitment is declining. • The upper population level is stable because any decrease in density results in increasing recruitement.

49. But is this the maximum?? • How high should we push it? • Maximum would be a little above 30. • This is the maximum sustained yield. • It is unstable because any reduction in N will result in declines. Usually avoided.

50. But…. • The major assumption of the fixed quota harvest model is that there is no stochastic variation in factors that influence net recruitment. • Means no uncontrollable changes in population density due to weather, etc. • Cows in a pen, which wildlife populations are not!