Compensatory vs. Additive Mortality

One strongly held belief by wolf advocates is that the elk killed by wolves is compensatory. The principle of compensatory mortality or predation argues that the wolves kill only elk that would die in that cycle anyway and thus have no effect on the overall elk population. In other words, to paraphrase Mech, elk that die for one reason cannot also die by another reason.

The theory is based on the belief that the wolves select the weaker animals more likely to die anyway. I cannot doubt some of that happens at least by pure chance. But in a relatively stable system already populated by other predators that prey on elk (humans, grizzly bear, and cougar) the addition of wolves can only be additive. Although the wolves may indeed take some prey that would otherwise have died by natural means or the other predators, the other predators will make up for their losses of those animals.

The alternative is additive mortality; i.e. each wolf-caused elk kill adds to the total elk killed in a year. That seems a more appropriate model for adding wolves to a system inhabited by other predators, including humans.

So far although I have found some claims that observations support at least some compensatory mortality in some areas I haven't found research testing the hypothesis. Most of the research suggests "it depends" on things such as the predator to prey ratio and densities and the effects of other predators including human hunting. Some of the discussion suggests that human predation operates in a contrary manner, selecting the healthiest animals most likely to otherwise survive.

Clearly if the elk population in a wolf inhabited region is dropping that is evidence the wolf kills are not all compensatory. On the other hand some will be compensatory in all wolf inhabited environments through sheer chance.

Christianson discusses another, perhaps more important effect which he calls the "Risk Effect". Risk Effect

 

 

The figure summarizes his findings for 12 elk herds before and after colonization by wolves, showing a huge reduction in elk calf survival (recruitment) that cannot be predicted by direct predation and is not in line with predictions based on other factors such a snow pack. This suggests that the mere presence of the wolves as predators reduces the pregnancy rate of wolves leading to decline in the elk population. This more than offsets compensatory predation. He notes, " Recruitment, as measured by the midwinter juvenile:female ratio, was a strong determinant of elk dynamics, and declined by 35% in elk herds colonized by wolves as annual population growth shifted from increasing to decreasing....Collectively, these long-term, large-scale patterns align well with prior studies that have reported substantial decrease in elk numbers immediately after wolf recolonization, relatively weak additive effects of direct wolf predation on elk survival, and decreased reproduction and recruitment with exposure to predation risk from wolves."

Mech makes an interesting point that this principle can also affect the wolf population. Mech He also notes that higher wolf mortality can positively affect pup production and reduce the wolf mortality from other wolves. This leads to the need to cause relatively large (25% to 50%) reductions in the wolf population through hunting or other means to render it stable or reducing.

Models of Elk and Wolves

Predator/prey models have been around for a long time. I am sure that some quite sophisticated ones exist today to describe reasonably complex ecosystems. My research on existing models is only beginning.  I’ll do some simple scoping work on my own to help figure out what to look for.

My first model will address the relationship of wolf killing of elk (not necessarily the same as wolf eating of elk) and the relative populations. My first hypothesis is that the number of elk killed by the wolves in a given ecosystem equals the amount of new elk production each year; i.e. the total surviving calves accounting for reproduction rate (births) and all causes of death of both the calves and the rest of the herd except for the losses to wolves. Or,

kW = rE

Where:

W = number of wolves

E = number of elk

k = number of elk killed each year by each wolf

r = average surviving net overall reproduction of the elk, as a percentage of the total elk population, not accounting for those killed by wolves

There are many assumptions in this simple model which I will not address at this time. But I will note that elk kill by other predators and natural deaths can be included in r.

Now let’s consider some numbers that are at least close for the ecosystem of Yellowstone National Park. The number of wolves we are told they think they want to have is about 100. I haven’t heard how many elk they’d like to have but historical counts range from just under 20,000 to the last count in 2013 (they didn’t report one for 2014) of somewhat under 4,000.

Numbers in the literature for k range from a low of 11 (as used in the elk “reintroduction EIS) to a high of about 35, with a frequently claimed average of 21.6. The number varies depending on prey concentration and other factors. But I’ll use 20 as a start.

r also varies. The estimates are confounded by the makeup and quantity of predators included in the estimate. But about .20%, or .2, seems to be an average number for a healthy elk herd.

So, substituting in these numbers:

20 W = .2 E, or

E = 100 W

So if Yellowstone wants 100 wolves (W = 100) then E = 10,000. Oops. That means they need more than twice as many elk as currently remain to satisfy the 100 wolves they currently estimate. That means the remaining elk are going to be killed at a rate far above what they can match by reproduction. The elk herd is on its way to extinction.

Or, if Yellowstone has about 4,000 elk (E = 4,000), the stable number of wolves W = 40. Oops. They say there are currently about 100 wolves. So the current wolves are going to have to change their diet, leave, or starve.

Clearly 100 wolves and 4,000 elk are out of balance. Worse, as the number of elk declines because there are too many wolves killing them, the number of sustainable wolves also declines. From the current situation the only stable result for this simple model is E = 0 and W = 0. Double oops.

You might argue that the 20 elk killed per wolf is too high. But then so is the 20% recruitment not including the other predators;  in Yellowstone most notably grizzly bear.  I have found models relating the Elk kills by wolves to the ratio of elk to wolves. It appears to max out at over thirty Elk per wolf per year when the elk to wolf ratio is above about 60; i.e. about 6,000 wolves in Yellowstone with about 100 wolves. It reduces at lower elk to wolf ratios. Although it should go through zero kills when there are no more elk (elk/wolf ratio of 0) there does not appear to be good data on the relationship at the lower level. That is what would help predict a “stable” population.

Wolves also reproduce. Our simple model doesn’t account for that. So whatever the number of wolves, unless they are killing each other, taken by disease, or starving at a rate that matches their reproduction, then their number will increase. We have witnessed just how fast the wolves can increase over the last twenty years, where about 50 multiplied to nearly 2,000 in about ten years. It has been proposed that they reproduce faster when prey are abundant and slower when prey are harder to kill (and thus the kills per wolf go down).

One can move on to more complex models that bring into play second order and non-linear effects. For example the number of elk kills per wolf probably may depend on other factors such as competing predators (bear and cougar primarily) and weather. The number of elk depends on available forage; in particular that available for the winter.

One of the major assumptions of this model is an isolated population. Both wolves and elk move. Elk can move to escape their predators and wolves can move to another area once they have depleted the elk in their present area. They seem to be doing that in Idaho; e.g. after depleting the Lolo, Sawtooth, and Selway regions the wolves seem to have moved on to adjacent regions.

Finally I’ll note here that the classic predator relationship is expected to vary over time, as for example with jackrabbits and coyote. The prey goes through a sine like up and down population over time, with the predator population following but usually at reduced amplitude.  Or you can look at the other way: the prey follows the predator. Both perspectives are right. It is like chickens and eggs: neither comes first. They vary together.

In conclusion this very simple model provides some numerical insights to start with.  Things aren’t stabilized yet in Yellowstone. The final result is likely to be even fewer elk and wolves; possibly the wildlife desert that Lewis and Clark described when they traversed this area.

More Numbers

I know that numbers don't change most people's minds. But one purpose of this blog is to keep the information I find and develop.

When the wolf experimental re-introduction was agreed to it was also agreed that the goals would be met with about 100 wolves: ten packs of ten. Some suggest that might be for each of three different areas, so maybe 300 max. The following is actual MINIMUM wolf counts by the U.S. Fish and Wildlife Service. It is on their front page:

 

As you can see the actual numbers outstripped the agreed to numbers by over 500%. This is because the USFWS was supposed to manage the number under court order. They seem incapable of doing so.

Where Might This Go?

In my earlier years I was something of a wolf apologist. I had read Farley Mowat's "Never Cry Wolf" and believed it was non-fiction. He claims that most of the diet of the wolves he came into contact with was small animals such as mice and voles, etc., and that they had little to no taste for the Caribou in the area he went to. That might even have been true for areas where the Caribou herds are not resident throughout the year. But I didn't realize that didn't translate to Elk in Idaho.

My wife, with my agreement, even sponsored a wolf at a wolf recovery center. Little did we know.

We live reasonably close to Yellowstone National Park (YNP). We have lived even closer and since 1970 have been sure to visit for multi-day trips at least a couple of times a year. We have backpacked through YNP for multi-day trips a number of times.

Elk by the hundreds greeted us in YNP on each of our multi-visits. Sharing them with our sons was one of our joys. Looking forward to the possibility of seeing bear and wolves was also enticing. We did see some bear but so far haven't seen any wolves.

Alas I began to notice a substantial reduction in sighting Elk a few years after the planting of the Canadian wolves. I didn't yet realize what was going on but began to get concerned. I started digging into what was known about the Elk herd in YNP, and was shattered by what I found. I had no clue that each wolf killed, on average, over 20 Elk per year...higher in some instances. When I looked at the exponential growth in the number of wolves that was happening under the mismanagement of judges and lawyers I was appalled.

I was also having bad experiences in my previous Elk hunting areas in Idaho. Live Elk were diminishing and signs of predator kills were growing.

It kind of came to a head this year. On my first day of Elk hunting I sat on a ridge and heard a pack of wolves yapping and then howling for several hours. I didn't see an Elk that day or for the rest of trip. On the second day a friend of my son came up and hunted with him in the morning. His friend had a deer tag (we were muzzleloader hunting mostly for Elk and also for doe deer) and shot a deer at first light. My son was right there. They went down to clean it and in a few minutes two wolves came crashing down from the ridge right at them. The wolves came within about ten yards and then split up, one staying above them and one circling below them. They were able to keep the wolves at bay as they retrieved the deer and left.

The next week (September 2014) wolves killed a dog in the yard at a house near mine.

I had also seen a couple of full-page ads in our local newspaper, and on their website, supporting the uncontrolled growth of wolf packs.

I decided it was time to get more active on this topic.

"This" in my topic statement isn't definitive. It might mean this blog. For that I intend to continue to research and contribute where I can to overall game management in Idaho. I don't consider the wolf as fundamentally different from other predators such as bear and cougar. But I now know wolf lethality in Elk is an order of magnitude larger. Thus their numbers need to be an order of magnitude smaller.

"This" might mean the whole wolf thing. I know I can't predict where that will end up. I doubt we'll be able to put the cat back into the bag and again eliminate wolves from Idaho. (I see estimates of over 60,000 Gray wolf in Canada and Alaska so remain confused as to what the Endangered Species Act has to do with wolves in Idaho). I suspect it is unlikely we'll even be able to get wolves managed in YNP and thus have to live in one with the  new animal desert numbers of both wolf and Elk in YNP.

Meanwhile I bought my first wolf tag yesterday.

And lament the poor Elk. I generated the following chart using the data from the USFWS in the following post (which I thought was a lost post but found sitting in "draft posts".) I multiplied the number of wolves in that chart by 21.6, the average number of Elk killed per year by each wolf. That is an average number and it is variable. The lowest I have seen as just over 11. The largest about 35. It is affected by predator/prey relative abundance, season of the year, other game, and other environmental factors. But whatever number in that range you might favor the result is the same for me: unacceptable.

Beaver and Wolves

I heard a Ranger in Yellowstone last month claim that one of the benefits of wolves in the Yellowstone Ecosystem was a resurgence of beaver. He claimed 100 beaver...but was misinformed in at least two ways. I reported in an earlier post how giving wolf killing of Elk credit for increasing beaver food was simply a lie.

I found this today in a YNP WEB posting: "To help restore the population of beavers on Gallatin National Forest, 129 beavers were released into drainages north of the park from 1986 to 1999. Park-wide aerial surveys began in 1996 with a count of 49 colonies and increased to 127 by 2007; dropping to 118 in 2009 and 112 in 2011."

The Ranger neglected to note that the beaver increase was due to planting. Young beaver travel upstream to create new colonies. Yellowstone is upstream from the planting locations. His other mistake was his number should have been colonies. And at least in this data the numbers are decreasing since the planting.

The more likely cause->effect chain is that beaver swam upstream and built new dams.  In other words Yellowstone beaver were planted. The new dams from the planted beaver encouraged more willow growth. I witnessed that last month as my Elk hunting campsite. There were several new beaver dams and the willows were going crazy. Since the Elk never hung out in that area on the road I'm sure the wolves that killed the Elk on the surrounding mountains had no impact on that.

I suspect the relationship of Grizzly Bear to beaver is more profound. I have seen beaver houses dug up by Grizzly in the Bechler area. I don't think wolves do that. They are too busy killing Elk.

 

Here is a surprisingly realistic view on this topic by a pro-wolfer:  Wolf Blog  The article notes,

"Mech’s primary point–that correlative evidence is insufficient for establishing causation–is important, and I hope it does not get lost here."

 

Just to be clear: I don't argue that the wolves have not had an effect in Yellowstone or elsewhere. Clearly they have devastated the Elk herd in Yellowstone and other locations. Crashing the Elk population by 80% is certainly going to allow more growth of their winter browse. I have also recently seen more deer and antelope in Yellowstone than in the previous 40 years. This is only an anecdotal personal observation but it caused me to wonder what that might be about. I recently found a suggestion as to causality that might be worth investigating. The suggestion is that the wolves have killed off many of the Coyote, and the Coyote used to preferentially eat the antelope and deer fawns. It also suggested wolves don't bother with the small fawns of deer and antelope. That's something worth following up on.

 

 

Another Elk Death Sentence

A court in Washington D.C. just took away Wyoming's ability to limit the devastation caused by wolves in their state. How our government can allow people in Washing D.C., who have probably never seen an Elk, take control over our lives and allow the predators that can come onto our property is beyond me. They have no accountability for their actions.

They have sentenced thousands of Elk to untimely deaths by the vicious Canadian predators. Here's what one of the ladies who visits my yard thinks of that:

 

Here's a helpful video on the topic:  Elk Video

 

Some recent info from the Rocky Mountain Elk Foundation suggests this atrocity might be solved soon:  http://www.rmef.org/NewsandMedia/PressRoom/NewsReleases/RMEFSilverLiningsinWyomingWolfManagementRuling.aspx

Why These Canadian Wolves are an Invasive Species

The wolves introduced into the Northwest do not appear to be the same as the ones that used to live here. There are tens of thousands of wolves in Canada (where they were taken from) and thousands in Alaska. Thus it is beyond me how they are considered an "endangered species".

Here is a source of information on this:  Not a Local Wolf at All 

 

Imagine a couple of these racing down the mountain at you as you are starting to clean a deer...as happened to my son and his friend a couple of weeks ago in Idaho not far from where I live.

To quote, "It was and is common scientific knowledge that the native male wolf (Canis lupus irremotus) of the Northern Rockies averaged 90 to 95 pounds at maturity. The wolf USFWS brought in as a replacement was a noticeably larger wolf (Canis lupus occidentalis) from north-central Alberta, with mature males topping 140 pounds, and some specimens weighing up to 175 pounds."

The article goes on to note, "Under the direction of Mollie Beattie, USFWS developed the Environmental Impact Statement for the reintroduction of wolves. That EIS made a number of assumptions about bringing wolves back to Yellowstone and the Northern Rockies. Almost none of those assumptions has proven to be correct, according to Toby Bridges of the Montana Chapter of Sportsmen for Fish and Wildlife. Writing in 2010, on the group's website, Bridges says: “Instead of getting just the 150 wolves Montanans agreed to back in the mid 1990s, the state is now home to likely 1,000 to 1,200 wolves… This year a minimum of 43,500 elk will be eaten alive or killed and left behind by wolves in the Northern Rockies...”

Bridges also states that “The U.S. Fish and Wildlife Service manipulated science, and replaced the native wolf of this region with a totally non-native...larger...and more aggressive wolf, and has consistently underestimated wolf numbers by half or one third of actual numbers.”

Article with Scientific References

Wolf proponents claim with great vigor that the Canadian wolves are representative of the wolves that lived in the northern Rockies. (Great vigor does not equate to good science). They quote skull studies that show only about a 10% larger average for the imported population from historic skulls. The wolves that live in Minnesota are 30% smaller than the imported Canadian wolves.

You can draw your own conclusion on this topic. Even if they were the same wolves my that would not affect my conclusion that they should not have been planted here. What was gone is gone. I don't see anyone arguing to reintroduce polio into our environment (thankfully).