Sunday, December 07, 2014

What Happens When A Breeding Wolf Is Killed

“Lethal Control of Wolves Provides No Benefit to Livestock”

“Why A Ravening Wolf is a Sheep’s Best Friend”

Those were the headlines yesterday, as media outlets continue to hype a flawed Washington State University research paper that I panned over on Wolf Watch. The WSU researchers noted that through a certain time period:

1) the wolf population increased;

2) livestock depredations by wolves increased; and

3) control (killing) actions wolves to limit livestock depredations increased.

The WSU paper concluded that it was the increase in wolf control that caused the increase in livestock depredations (rather than the very large increase in the number of wolves).

Reminds me of the Ice Cream Murders which found that large cities have increased murder and violent crimes during hot months. During the same time period, sales of ice cream skyrocket. Does this mean ice cream turns people to murder?

Looking for a diversion, I checked my social media feed and found numerous posts about how killing wolves only increases the population when one of a pack’s lead wolves is killed, disrupting the pack’s social structure and making way for more members of the pack to breed. So, you silly ranchers, if you want to save your sheep, don’t kill wolves. Argh!

That someone would believe this stuff makes me crazed. If you’ve got wolves killing your sheep, often the only way you are going to stop it is to kill the wolf/wolves doing the damage – or remove your livestock. The wolves won’t have some Kumbaya moment by the light of the moon that turns them into vegetarians instead of meat eaters.

It’s time to review what is actually known about the effects of the loss of a breeding wolf from a wolf pack – not theory, not modeling, but what has been documented. This issue was addressed in a paper in the Journal of Wildlife Management in 2008: “The Effects of Breeder Loss on Wolves,” written by Scott Brainerd and 18 contributors. The Brainerd paper summarized nearly 150 records of breeder loss in wolf populations around the globe from 1970-2003 and found:

• Wolves reproduced within territories the season after breeder loss in about 47% of cases. (Less than half.)

• Breeders were more likely to be replaced within 12 months where breeders of one sex remained (60%) than where breeding pairs were absent.

• After a breeder loss, if the pack doesn’t reproduce the next season, the pack size is smaller than if the pack does reproduce. (Yes, this is a duh).

• The ability of wolves to reproduce the season after breeder loss was greater in cases where one breeder had to be replaced, than in cases where both breeders had to be replaced.

• The average time it takes for breeder replacement differs with the size of the wolf population. Recolonizing populations with less than 75 animals take an average of 19 months for breeder replacement, while populations with more than 75 wolves take just over 9 months. Average times to next reproduction were 22 months in small wolf populations, and 12 months for larger recolonizing populations.

• In 38% of cases, wolf packs dissolved and abandoned their territories after breeder loss, leaving territories vacant or occupied by solitary wolves. Of these dissolved groups, 53% became reestablished when occupied by new wolves, or when the remaining solitary wolves found new mates. In 21% of cases, neighboring wolves usurped vacant territories. When the cases in which neighboring packs usurped territories were excluded after breeder loss, wolves became reestablished in territories after an average time of 2.72 years.

Montana State University researchers Scott Creel and Jay Rotella co-authored a 2005 paper on human-caused mortality and wolf population dynamics (entitled “Meta-Analysis of Relationships between Human Offtake, Total Mortality and Population Dynamics of Gray Wolves”) that examined 21 North American wolf populations and the relation between total annual mortality and population growth to annual human offtake. The paper noted that the Northern Rocky Mountain wolf population increased 15-fold over the preceding 15-year period. The paper’s findings “reinforce the expectation that harvesting is not likely to increase reproduction or decrease natural mortality by reducing competition for resources.”

The complexity of breeder loss on social structure was also revealed in “Impacts of Breeder Loss on Social Structure, Reproduction and Population Growth in a Social Canid,” by Bridget Borge and three co-authors (including Brainerd), published in July 2014 in the Journal of Animal Ecology. These researchers examined a 26-year dataset of 387 radiocollared wolves in Denali National Park and Preserve, Alaska. Borge, et. al, concluded: “The importance of individuals to the dynamics of populations may depend on reproductive status, especially for species with complex social structure. Loss of reproductive individuals in socially complex species could disproportionately affect population dynamics by destabilizing social structure and reducing population growth. Alternatively, compensatory mechanisms such as rapid replacement of breeders may result in little disruption. The impact of breeder loss on the population dynamics of social species remains poorly understood."


Anonymous said...

all these statistics, percentages, hypotheses make my 67 yr old head swim. methinks let the wolves be wolves & populate and let the ranchers utilize guard animals to thwart wolf attacks. too simple theory? where am I going wrong?

Franklin said...

Clearly, the wolves were feeding and doing their thing in their native habitat long before someone decided they could make some $$ raising tasty sheep on the latter real estate.

Not unlike the Native Americans that got in the way of "progress," it became simply more "expedient" to simply KILL them (you decided which....) to solve their elusive dilemma.

Nowadays, the really clever $$$ seekers simply conduct a Govt. funded "study" that concludes with the proverbial caveat: "More research is in order....."

Cha Ching!

Anonymous said...

I've hesitated responding here, not wanting to stir the hornet's nest too much, but, well, being the token wolf-hugger commenter on this blog, I figured it was expected of me. So, here goes.....First, yeah, I agree with 67 yr. old Anonymous, AND, lupine lover though I am, I fully agree that ranchers/farmers should be allowed to target individual wolves or packs taking their livestock. I mean, that just HAS to be done eventually--even the most radical AR often has a change of heart regarding predators when little Snoozie or Muffin gets snatched from the back porch....And being a longtime wolf aficionado, even long before the wolf pendulum swung to a more positive outlook by the general public regarding wolves, I've read reams of what amounts to propaganda both for and against wolves. Both sides of the issue can get rather unrealistic, and twist study results to favor their views, so I always take these "statistics" with a large grain of salt. Make that a 50 lb. mineral block! And truth is, those statistics, even if they ARE true, may not make a bit of difference regarding someone's individual experiences with wolves--wolves have a way of "breaking the rules" we humans are always trying to label them with! There is no doubt that killing alpha wolves in a pack can most assuredly cause a pack to disperse(in other words, the original pack no longer exists as a social unit), and subordinate wolves that would NOT have bred will now pair up and breed, and CAN, in some circumstaces, temporarily raise the numbers of wolves in a given area. Temporarily. And 47%? Man, that sounds like a LOT, to me! I guess that's a glass half-empty/glass half-full sorta outlook, though. Whatever. And what pro wolf people often forget, is that other WOLVES kill Alpha wolves in rival packs and cause natural(not manmade, in other words) dispersals of this nature all the time. But if intense human wolf "control" continues, however, especially in the way it did in the past, subordinate wolves can pair and breed till their tongues hang out, and it won't do the species' numbers any good--wolves cannot reproduce like ungulates or rodents--apex predators are always vulnerable to severe controls, which is why they got wiped out over most of the continent(North America). Us wolf enthusiasts would like to see the spread of wolves to more of their original ranges, where they have the land and prey base to do so, but if they get "controlled" strictly in the few areas where they now are, that ain't happenin' except with anal federal government control of the wolf controllers! Yeah, please; people on both sides of the wolf issue would just as soon the feds stayed away! As I said, I'm all for people being allowed to defend their livestock and personal safety, if necessary. Canada has allowed this forever, of course, and they have plenty of wolves. What I AM NOT for is sport hunters wanting wolves killed so they have more wild game to shoot themselves, disrupting packs and causing grief and misery to wolves in wilderness areas far removed from any human concerns or potential problems--there OUGHT to be SOME places wolves can live their lives out according to their own dictates, without human interference. Gunning down wolves from frikkin' airplanes in wilderness areas in Alaska, for instance? PLLLEEEAAASSSEEE! Game Departments want to increase ungulate numbers?(really? Above and beyond the carrying capacity of the habitats? When has THAT ever worked long term?) How about controlling the number of sport(as opposed to subsistence) hunters for awhile? Well, of course, wolves don't BUY hunting liscences or supplies, etc. It ain't about doing what's right(in my opinion, anyway), it's about economics!....L.B.

Jack Elliott said...

I always love nature's counter-intuitive ways, and find it amusing when humans, stepping in to "correct" a "problem," do something that turns out to have the exact opposite effect.

Anonymous said...

.....and though not entirely on subject, let me plug Cat's new book out--it IS partially about wolves! "When Man Becomes Prey", available at Amazon fairly cheaply--even for a financially challenged peasant like me!(see my review on Amazon). And it is very fairly, sensibly, and interestingly written(even from a Predator-Huggers point of view)--not sensational or unrealistic as many of these critters-eating-people books can be(I know, as I read them ALL!). Highly recommended to anyone going for a ramble(or living in) areas where large North American predators inhabit(or soon will)--as well as for the critter geek types like myself who just enjoy reading and learning more on the subject....L.B.