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.

Dr. L. David MechWolf Biologist

“A 50-year Career of Wolf Research”Friday, April 17, 2009

4:00 pmMarshall Auditorium

Reception to follow

Summary

• 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

here

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.

• Habitat is the medium in which energy is captured…or not.

• So ecology is the play, habitat is the stage.

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!

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…

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.

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)

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???

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

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.

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.

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!

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

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!

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).

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!

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.

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

And besides…

• Wildlife populations were “endless”!

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.

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

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.

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.

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.

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!

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.

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!

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).

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?

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

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.

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.

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!!

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%.

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!

Induced rate of increase

• 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

here

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.

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.

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.

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.

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.

N K

Net recruitment

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.

N K

Net recruitmentor

harvest

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

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.

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.

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??

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.

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.

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!

Results?

• Basically, can be shown that eventually, you will overharvest the population and it will decline, possibly to extinction!

• Gave you this model to show you the rational used to manage wildlife!

Better models?

• Fixed quota harvest is not good in most cases, are there others?

• Fixed proportion harvest strategy

• How does it differ? Still fixed but now it uses proportions.

• So number harvested changes depending on density.

Makes sense, kind of…

• Thus, if population declines for stochastic reasons, percent taken is the same but the absolute number is less.

• Result should be a changeable but sustainable yield with a stable population density even in the presence of stochastic variation

• Sounds good!

But…

• This requires managers to have perfect information on abundance of the species to set the quotas.

• Rarely do they have this information and even if they do, usually not in time to set quotas.

• Usually they base it on past success!• Needless to say, they are often wrong and

overharvesting is possible.

What else?

• Constant effort harvesting strategy

• Instead of controlling the harvest, this attempts to control the harvesting effort.

• This is done via setting hunting seasons or limiting the number of people harvesting the population.

How does this differ?

• So now instead of saying you can hunt until you remove x or a proportion of N,

• You say you can only hunt x number of days or only so many hunters can hunt the area (usually also over a fixed time).

• This has a built in control mechanism in that the number of animals killed over the fixed time will be dependent on abundance.

High density/high success

• If population is low, hunter success will be low and the total harvest will be low.

• If population is high, just the reverse.

• So it is somewhat self regulating and IF you set the season length or the number of hunters for the lower population levels, should avoid overharvesting

Others?

• Fixed escapement harvesting strategy

• This is based on the idea of maintaining a population at a given level and only if it goes over that level, can you harvest individuals.

• Excess individuals above this target threshold are termed escapement.

• Insures a minimum level of population

Is it used?

• Fairly new and is not favored by managers because of the variation in the harvest, including no harvest in low years.

• But it begins to recognize that game species are not just to shoot and actually are “used” by others in non-consumptive ways.

Do they work?

• These are the harvest models and look good on paper (maybe) but do they work in the real world?

• Needless to say, it is hard to strictly apply a mathematical model to real world, real people situations.

• “Most harvesting of wildlife… has been managed largely by trial and error”.

Seat of the pants

• So taking in consideration all the fancy models and math, we still control the harvest based on “what we feel is right”!

• Usually managers have been conservative so as to not overharvest but sometimes mistakes are made, still can’t predict what populations will be like

Additional harvest technique

• Age or sex biased harvesting.

• So far have talked about removing whatever animal from the population.

• This is common in species where sexes and age are hard to determine.

• Grouse/woodcocks (sex nor age)

• Ducks (sex yes but age no)

If you can tell the difference

• Most ungulate species can tell sex and age (at least in males)

• When this is possible, many argue should protect reproductive base (females) and reproductive output (young).

• This leads to adult males only seasons.

• Is this desirable?

Should we kill only the males?

• Population wise most expendable

• But… can lead to reduced hunting opportunities.

• Example: start out with 100 animals

• 50 females/50 males.

• If we just kill of males, can lead to skewed sex ratio where more of the population is females and less room for males!

• IF area can only support given number of animals AND you want to manage for hunting opportunities male only harvest can lead to reductions in these opportunities.

• Strategy is to maintain females at an adequate level for maximum production but low enough so that all the energy is not tied up in them.

Having enough males

• Danger of producing skewed sex ratios is not having enough males to go around!

Within males

• In New York, recently have seen the use of age harvest criteria within males (deer).

• Point limits, can only shoot bucks with greater than x number of points.

• Idea is IF we consistently kill off the young males (which often happens because they are more numerous), they never get a chance to grow into big ones!, which are more desirable to many.

Pros and cons

• Obviously aimed at “quality” of harvest.

• Makes sense IF this is your goal.

• Some argue that by doing so you are killing off the good genes (tested big bucks) and allowing inferior genes (untested) ones replace them.

• Again cattle: do you send your biggest bull to market??

So arguments go on

• Sex and age biased harvests have always been and will continue to be controversial.

• When I was in Michigan and they wanted to start a doe season, accused of killing bambi’s mom!

• Of course you could shoot good old dad!

Politics and harvest management

• This brings us to probably the most influential harvest strategy:

• Politics!• As mentioned, game agencies may

manage wildlife but the public are the owners!

• So a wildlife biologist may say all he wants about what is the best way to manage the harvest, but it is the public that decides!

Here

Political structure• This public input is insured by the structure of

most game agencies.

• There can be an agency director but above that person is the game commission.

• Commissions are noted for not being wildlife people, except that sometimes they may be hunters (but it is not necessary). They often are political appointees.

The process

• Field biologists make recommendations to their superiors.

• The superiors get together to propose policy.

• That policy is the adapted or not by the commissioners, often after they get input from Joe the hunter.

Joe the hunter

• Joe the hunter bases his opinion on how well he did last year!

• If he did good but the “experts” are proposing decreases in the harvest, they must be wrong, and visa versa!

• So we can have all the models we want but when it comes to harvest strategies, the final decisions are made by politicians who know little or nothing about wildlife ecology.

Summary

• How do we manage the harvest?

• Have models based on:

• 1) Agricultural heritage

• 2) mass action, no behavior of “prey”

• 3) biggest weakness, based on constant populations.

Summary

• Rarely work in real world so often managers do what they think is best or

• What they are politically told to do.

• Last important aspect: They are by nature single species concentrated.

• This we will address later.

Next: wildlife control (Chap 20)

• So, managing how many we can kill is difficult.

• BUT… if we can keep other species from killing them, we should be able to kill more our self…right??

Manage vs control

• How do they differ?

• In control we desire to purposely REDUCE a population to some lower level but not for some sustainable harvest level.

• In fact, most controlled species are not considered “harvestable”

• Harvestable meaning a species we kill for its use.

Control

• In control we are killing them because we don’t want them!

• So they are rarely used and discarded.

• Laws against “wasting” game species

• But ok to discard 1,000s of kg of controlled animals!

Why would we want to control?

• Before we go further, lets look at reasons we would want to control a species.

• Basic reason is competition:• Can be in two forms.• 1) one species is competing for resources

of a desirable species.• If we can control the first, leaves more

resources for the desirable one, more harvest!

Reasons for control

• 2) A species is competing directly for a resource desirable by us.

• Can be plant foods: they are eating our apples

• Can be for animal food; they are killing our animals (domestic or wild).

Need for control?

• So for one reason or another, WE decide there are too many of a given species.

• Often we make that decision capriciously without any sound basis, faith based!

• E.g. Eradication programs for predators

• How should we make those decisions?

When is control appropriate?

• Some may argue never, we are imposing our view on the natural systems!

• Some, who view the natural world as OUR garden and anything we can’t use are “weeds” needing to be controlled!

• Most see needs for control under certain circumstances

• E.g. introduced species, cats on islands (or is that the real case?)

Circumstances for control

• 1) when benefits exceed the costs

• 2) when “pest” species is in fact the cause of the perceived problem

• 3) when control has an acceptable impact on non-target species.

Cost/benefits

• A control action is undertaken to provide some benefit (should be real and not perceived!).

• Conducting the control action has costs (monetary/environmental).

Example: coyotes

• 2007 killed 90,326 coyotes

• Congress allocates $10M per year to kill 100,000 predators: mostly coyotes!

• Reasons: kill domestic stock, kill game species.

• 270,000 sheep/year (4% of total sheep population)

• ?? Game animals/year

Perceived benefit

• Less coyotes/ more sheep

• Less coyotes/more game

Is it worth it?

• It costs over a $100 for each animal that is killed while the damages incurred by the animal average $22.50

• Impact on game species debatable• Other costs:• 1 coyote eats 2,000 to 3,000 rodents/year• 90,326 = 180 million/year!• Rodents eat grass/plants that livestock

eat!

Benefits of coyotes!

• Jackrabbits: 100/year/coyote

• 90,326 x 100 = 9 million jackrabbits!

• Arguments made both ways, not sure which is the case because lack of studies!

Is the coyote responsible?

• Livestock: 273,000 sheep but likely inflated in that often, if a sheep does not return, assumed it was killed by predator: coyote!

• Again, still NO study showing definite negative impact on wildlife populations.

Impact on other species?

• Often use poisons to kill coyotes AND other species.

• Coyotes are part of ecosystem. What impacts are there upon its removal?

Is it ever advisable?

• So when is control advisable?

• Exotics your best bet

• Natural systems???

Why exotics?

• Often times easy to demonstrate they are the cause of the problem: but how?

• Cats on islands:

• Introduced to control house mice from ships (other exotic!)

• Killed mice but also ground nesting birds.

• How do we show it is the cause?

Controls

• In any effort to demonstrate effect, need controls.

• In this case, had islands where cats were not present.

• Removed cats and saw increase breeding success – 100% and decrease in chick mortality – 0 %!

• Was it from cats? Comparison with cat free island supported it.

So it can be done

• But it is rarely so.

• Why?

• Objectives of control often poorly defined or nonexistent!

• In any control effort, control in itself should NOT be the objective!

• It is a management action to achieve the objective

Objectives of control

• The reason for the control action should be clearly stated:

• E.g. increasing the density of a food plant from one density to a higher one.

• Usually “objective” of control effort is defined as trying to reduce the density of the species being controlled.

• E.g. we need to reduce this species by x percent.

• The management action then becomes the goal!

• Example: never any clear objective and eventually, just did it because….

• Some “objectives” shown not to be accurate: deer had little effect on erosion.

Back to coyotes

• Coyotes (and predators in general): we know they kill sheep and game but have very little data to demonstrate that “controlling them” leads to x # less sheep killed or y # more game in the field.

• In fact, we kill over 90,000/year and sheep industry suffers the same level of loses/yr!

• Control becomes a means in itself!

Length of control operation

• How long should you control a species?

• Important because once you start the cost/benefit depends on how long you need to commit resources to this.

• One year? two years? Forever??

• To understand what your getting into lets look at the process of control.

Process

• In any control operation, biologically we are doing same as in harvesting:

• Lowering population via some form of killing.

• In the harvest we WHAT the population to rebound.

• In control we don’t want it to do so but…

Same process

• Same process that we hope gives us sustainable yields (higher recruitment rates because of more resources/individual), also applies to controlled populations.

• Population will spring back!

Coyotes again!

• In control operations against coyotes, find that remaining coyotes have increased litter sizes!

• Wild horses/donkeys U.S.: same trends, remove animals but population just comes back!!

So control is forever!

• Desert bighorn and cougars: attempting to keep sheep populations going in the face of other factors by reducing predation.

• Sheep will never get to a point where they will be self sustainable WITHOUT cougar control!

Conclusion

• Be sure you have clear justifiable objectives for control….not just because you think it will work!

• Be sure you have data on collateral effects from control efforts

• Be aware that you are embarking on a long term commitment.

• DON’T enter into it lightly!!

here

Ok, it is justified

• How do you do it?

• First is by manipulating mortality: killing them!

• Humane considerations need to be taken into account (often difficult to do). Even the most obviously deleterious species will have defenders.

• The worse thing to do is make a sport of it!

Your set to kill

• What should be the appropriate control strategy?

• Return to harvest strategies: the one that was most prone to overharvest?

• Fixed quota harvest!

• Saw earlier that even if you have a stable population, can remove enough to cause overharvesting.

That is what you want!

• You want to exceed the maximum sustained yield!

• Add to that the instability of populations, a fixed quota harvest, set to overharvest would provide the maximum control and could even cause the population to go extinct.

Again, trick is how many

• Because you can overharvest anywhere on the curve, setting the target kill then affects the time it takes to reach eradication.

Examples

• Setting the kill rate of feral goats in aNew Zealand park at 90%, each year would lead to eradication in 12 years.

• If it was only 50% it would take 50 years!

Other factors?

• Again, easy to say we will kill certain number of animals/year but… as mentioned, the less there are, the harder they are to get!

• Adjust to hunting pressure

• Adjust habitat to hard to get to places,

• Adjust behavior: cows in Mexico.

• Judas goats

Besides hunting them?

• Biological controls

Is this the way it should be?

• If all we want is to “ranch” a single species, ok.

• But is that all we want?

• Is that what is good for the ecosystems that support these desired species?

• Sacrificing keystone species and ecosystem health for one single focused use of the ecosystem.