Hunters Vs Wolves
- A.L. Exley
- Jan 24
- 9 min read
A Sign of the Times
This photo surfaced on Facebook in a Voyageur's Wolf Project post of a billboard paid for by The MN Deer Hunters Association, blaming wolves for the loss of 54,000 deer fawns every year in Minnesota. Using words like 'devour' and the sweet image of a young fawn, the billboard appears to argue for the management of wolf populations to protect Minnesota's deer herds - for the benefit of more deer available to Minnesota deer hunters.
The Voyageurs Wolf Project brings up several concerns regarding the legitimacy of the numbers on the board, which will further be explained below. This post will also explore the research of wolf predation on deer fawns, and wolf and deer ecology.
To begin, we will start by discussing number-hurling, one of the most common misused of scientific information in the media.
Number-Hurling
Number-hurling is the act of using a number, statistic, or other forms of data to support a claim. The difference between this and sharing scientific information is that not much (if any) further information is given.
Numbers without context are arbitrarily. Take this quote: "150,000 people die every day". That seems like a lot - until you consider that the human population on Earth is approaching 8 billion, meaning .001% of the human population dies every day.
With that in mind, the next question should be: what does 54,000 mean for deer in Minnesota?
Deer, Deer, Deer
Most sources estimate Minnesota has a white-tailed deer population of about 1 million, give or take a ten-thousand. Since it is difficult imposable to count the exact number, most population information comes from statistical models and hunter harvest data.
Links to Deer Population information:
This PDF talks more in-depth about estimating animal populations using methods like Plot Sampling and Distance Sampling. These methods involve surveying a randomly selected area for the animal. The number of animals counted is then divided by the survey area, presenting an animal density.
There are 86,943square miles in Minnesota. If we randomly selected 1-square-mile study areas across the state, and calculated 11.5 deer/square mile, that would give us about 1 million animals. The animals are obviously not perfectly spread out across the state, but we have a population estimate for statical purposes.
54,000 divided by 1 million and multiplied by 100 is 5.4. This means according to the billboard, wolves killed 5.4% of deer in a single year. But there's a problem with this math - the number 1 million references all deer, while the number 54,000 only refers to fawns. In order to find out what percentage of fawns are being killed by wolves in Minnesota, we have to estimate of the population of deer under 1 year old.
How Many Fawns are in Minnesota?
The truth is - we don't know how many fawns are in state.
Fawn populations are more difficult to estimate than adult populations because fawns >6months old are very good at hiding. For the first couple weeks, a fawn's main survival method is curling up in the grass and hiding. Conducting any sort of survey to count fawns by hand is simply not efficient due to the number of fawns that would be missed.
A mature doe has 2 fawns per year on average (young mothers with smaller body sizes typically have 1 fawn, and older, healthier does have twins, or sometimes 3 - 4 in a single spring). So, why can't we multiple 2 fawns for every adult female deer? We don't know the number of female adult deer either.
Even if the sex ratio of a population was 1:1 (one male for every female), we don't know how many of those animals are mature. If we tried to multiply 2 by half of the population, we would be assuming that female fawns are also giving birth to two fawns. The ratio is most likely not 1:1 either. A healthy deer population has more females than males, since they reproduce polygamously. (More males than females leads to more reproductive competition, which could reduce survival rates of mature bucks).
For Heaven Sakes - What DO We Know?!
We can estimate fawn survival rates. This website from the University of Georgia talks in depth about whitetail fawn research and methods.
A common tactic is to use VIT's on mature does during the winter. In the spring when the doe gives birth, the tracker falls out and sends location data to researcher. Using the data, researchers find the newborn fawn, take measurements, and fit it with a radio collar to monitor it's movements. The collar expands as the fawn grows, and if the fawn survives after the study ends, the collar falls off. If the fawn dies during the study, the collar sends out a mortality signal after a period of non-movement.
These mortality studies cannot be used in estimating fawn population for a couple reasons.
The location the fawns are found at is not random. The randomized selection of study areas prevents skewered data. If we count deer at a known feeding location, and use that survey data to estimate the population of other locations, that data would reflect only the area where deer are being feed. In other words, the population estimation would read as if deer have food everywhere - which they do not. Food resources are not equally distributed everywhere. There are places animals go often and places they avoid entirely. Randomized location provide a middle-ground. In monitoring surveys, the priority is to collect as many fawns as the survey needs. Researchers will purposefully choose locations they can catch the most does (over bait, at a water source, along prime bedding and feeding habitat).
There are a limited number of fawns. Part of the goal of a survey is to count as many animals as possible. In mortality surveys, the opposite is true - use as few animals as possible. Wildlife research is bound to the same laws and guides as laboratory animal research under the Institutional Animal Care and Use Committee (IACUC), along with state and federal regulations. The goal of any research project regarding animals is to be as non-invasive as the study allows, and use as few animals as possible, or substitutes for live animals whenever possible. Read more about the 3R's in Animal Research.
HOWEVER - data from fawn mortality studies can give us information about wolf predation.
This paper from the US Geological Survey looks at mortality rates of white-tailed deer fawns who were predated on by wolves and black bear in Minnesota in 1994. In this study of 21 tagged fawns, 51% were predated on by wolves, and 49% were predated on by black bears. This paper from Todd Fuller also points to wolves being the biggest cause of mortality on the sampled fawns.
Natural Selection At Work
By now, we've all heard of Charles Darwin and his theories of evolution and natural selection. Part of natural selection regards overproduction.
Sea turtles, rabbits, insects, and fish are all examples of animal that produce more offspring in a single breeding event than can reasonably survive. This overproduction is a natural remedy to predators who will eat the excess offspring before causing a dip in the population.
This is why researchers make a distinction between fertility - the number of young that are born to an individual, and recruitment - the number of young that reach sexual maturity. As cute as those baby animals are - they don't do much for a population until they reach the age they can breed. If a population is decreasing, fecundity, fertility, and recruitments are all factors that should be investigated.
With all that in mind, we have no idea what the population of deer fawns is in Minnesota, therefor, the number 54,000 can not give us any information, aside from the fact it is only 5.4% of the total estimated deer population.
Where did 54,000 come from?
According to the International Wolf Center, there are about 2,699 wolves (give or take 700) in Minnesota as of the 2020 Wolf Survey. We could estimate the number of fawns killed by wolves by multiplying the number of fawns an individual wolf kills by the total number of wolves. However, as the Voyageurs Wolf Project points out, that is also a difficult number to figure out.
According to a Wisconsin News article, wolves kill 17 - 20 deer per year (no distinguishment made between fawns and adults). This study from Northern Michigan University claims 12 wolves killed 217 fawns over the course of 4 years. That means that each collared wolf ate 18 fawns - over the course of 4 years. Just for laughs, if we assume each individual wolf killed the exact same amount of fawns every year, that means that one wolf killed 4.5 fawns in a single year.
Search "how many fawns do wolves kill a year" and you will find a string of news articles with 'he-said-she-said' quotes and blog threads of passionate deer hunters. When it comes to raw data from researchers in the field, the answer becomes illusive. The fact that non of these estimates repeat is as big of a red flag as you can get in the science world, as reliable experiments have repeatable data.
In their post, the VWP referenced a paper that estimated wolves killed 17-20 fawns in Upper Michigan. If there are 2,700 wolves in Minnesota, multiply that number by the number of fawns killed, and you get 45,900 - 54,000. The billboard strictly assumes that each wolf kills 20 fawns per year. However, the statistic of 17-20 fawns per wolf was pulled from an article that made no distinction between fawns and adult wolves. Not only is the 54,000 based on questionable sources, but the sources it is pulled from makes it unreliable for not distinguishing between fawns and adults.
Every Year, a Wolf Counts to Twenty and then Stops
Funny enough, the billboard leads one to believe that the number of fawn killed by deer each year is a static number. It is not. How many fawns a wolf kills changes year to year, and depends on multiple factors.
In their own surveys of wolf kills, VWP saw breeding pairs kill more fawns than single wolves. This makes sense - breeding animals require higher calorie intact while pregnant and nursing.
It is also well-known that wolves change their predatory behavior depending on resource availability. In late summer, fawns are strong enough to follow their mothers instead of hiding, so wolves in northern Minnesota will turn to eating beavers, fishing, and even eating berries. Late summer is a particularly lean time for wolves, and is when most wolf pups die of starvation. This paper from Scandinavian research on wolves hunting moose determined that the age of the breeding male was a significant factor in a hunt's success, meaning older adults have more experience.
One important factor in fawn survival to consider is the health of the mother. Though they are born precocial, fawns are highly dependent on their mothers for the first couple of months on their lives, and typically stay with their mothers for their first year. Not only are they given food and groomed, but they learn foraging behavior and predator avoidance. This article goes into dept about how maternal health and dominance can affect survivability of fawns.
Another variable to consider is habitat. Deer can live in a wider variety of habitat that wolves and other predators can. Wolves, black bear, and mountain lions prefer habitat away from busy metropolitan areas, whereas deer can live in wooded patches of suburbs in the middle of a small city. Fawns living in these areas would not be predated on by wolves because there are no wolves around (though there are coyotes). This article talks more in depth about the different mortality rates of different habitat types of whitetail deer.
In Summary
While its known wolves consume a lot of fawns, their predation rates on fawns change through out the year, and vary by habitat, season, and experience. Fawn survival rates are also influenced by environmental factors and the health and dominancy of the mother.
The number of fawns killed by wolves each year is not a static number. There is little evidence to defend 54,000, and even if it were accurate, it is insignificant since the population of fawns and the birth rate of fawns in the state of Minnesota is unknown.
Wolves killing deer fawns in Minnesota is only one line in a vast ecological web. No single factor has ever been recorded causing a significant decline in a species. When a species is declining, there are always multiple factors at play.
According to the MN Office of Traffic Safety, between 2016 and 2020, there have been over 6,000 vehicle collisions with deer on the road. 1,000 of those incidents involved serious injuries or fatalities to the people in the car.
The MN DNR website says in 2022, the harvest report was 170,000 deer taken by hunters - which is also 7% lower than the harvest rate of 2021. Even then, that number is significantly higher than 54,000.
The billboard fails to mention black bear and coyote predation on fawns. Coyotes are significant because unlike wolves and black bear, they can live closer (even within) city limits, meaning they can affect deer populations in places wolves and bear cannot.
The Bigger Message
Wolves serve a role in the ecosystem that no other species, including humans, can fulfil. While they should not be evicted from the landscape, this doesn't mean hunting them should never be allowed.
As important as wolves are, they do often cause conflict over livestock, and people's general fear of the animals. Allowing controlled hunts mitigates conflict as well as reinforcing a fear of humans - a thing that helps keep the species alive.
Comments