Michigan deer season

[ChuckC]

You guys..  we are no different here in WI.  Battling the same problems, seeing fewer deer.  

Look at our gun deer kill stats for this year.  Dismal.  and of course, they blame the cold weather on the opener.  If it was hot they would have blamed that.

I don't know the answers.  I HAVE been on the other side during my long career with the FDA.  

What I said above, I believe as total truth.  I know more about FDA stuff than you do.  You know more about (your profession) than I do. Those folks in the DNR know tons more about deer biology and how it impacts the rest of the world than we do. That's what makes the world work.

They cannot be everywhere.  They cannot know that there are 100 deer per mile on Joe's private place down the road, and 3 deer on the public land I hunt.  Until we inform them.  Somehow there has to be a connection made.  A way to channel information from those that just walked those 100 acres and saw nothing, including tracks.  Then, once they KNOW that... well, what can they do ?  Yup, Joe has 100, he has crops and rotates his tree harvesting, and he doesn't allow hunting or access.  Their hands are kinda tied.

The difference between private and public agencies is huge, but, then again, not so huge.  All of it is driven by money and perceived power, at some level.

We need to do less "bitching" at the guys and gals who are out there, and somehow, someway, do more pushing and directing.  If they can't do anything because of the politics, then THAT is where the pushing needs to be directed.

For years we have "bitched" about some of our (Wisconsin's) hunting laws.  They were stupid, but they have always been there.  One day, our newest Governor said.. "they are stupid" (meaning, some high ranking political donors said they are stupid, and hindering commerce) and BAM... they were changed.  

The law enforcement side of the DNR said "oh oh, we are gonna see a big rise in * * * crimes because we can't trust anybody"  but they never happened.

We have the added pleasure of having CWD in our herd.  Anyone wanna guess how it jumped from Colorado to Wisconsin in a single bound ?  My guess involves money and commerce and power.

Right now, my little bit of forestry and wildlife training (I majored in Bio, but only superficially in wildlife related studies) says that Minnesota, Wisconsin, Michigan (esp the UP) was logged over years ago.  The new growth opened the doors for a huge growth in deer population, which wasn't there before. Right time, right place.  

That growth is now at the level where it mimics a climax forest with no understory.  My little place in the UP shows exactly that.  Lots of trees.... nothing growing underneath for food.  The soil is very poor.  Growth is agonizingly slow.  It can no longer support the large herds. Cedar and other browse plants are so overwhelmed by browsing that there is no real regeneration.  

But We all know this already.

So to change this, we need several things.  We need controlled removal of the trees, to start.  Regrowth follows, or.... we need to retrain our minds to what constitutes a good, healthy deer herd.  

The State doesn't do the tree harvesting, but it gives contracts to do this.  Again, money and power.  I perceive (but don't know) the lumber industry is not what it was in the past, at least in the north woods. Trees are probably not of the right size for lumber, but rather for pulpwood.  There appears to be less call for that.

There is also a call / push from a sizeable portion of our population to just leave nature alone.  Who is right ?  Who trips the Governors' chain and gets action?    Will it be us, or them ?

Coming up with a way to win / win with minimal cost to the public would go a long way towards successfully steering the politics.

Can we use trees to make ethanol (or methanol) ?

ChuckC

[ChuckC]

Mojo

Thanks for all that info.  We all need to read up on our history and what caused certain things to be.

We can make much more informed decisions and arguments that way.
ChuckC

[Mojostick]

I think bowhunting orgs need to reconsider everything they think they stand for. Many bow groups seem(ed) to exist mainly to fight crossbows, at least in the political/regulations arena. That was and is a losing plan of action. It's divisive for no reason, since crossbows will be coming to nearly all states in the next 20 years, except maybe a few western states. The baby-boomers, cash starved states that fund DNR's with large hunting populations and the hunting industry will see to it. As will the majority of hunters who want it. Trust me, I worked at Cabela's. Trad guys may not like crossbows, but literally 1,000,000's of US hunters want them.

I also believed and still believe that the political capital/good will with the non-hunting masses we Michigan hunters burned up over what is likely a 1 year wolf hunt over 40 some wolves will come back to haunt us for years, bigtime. The faux outrage many hunters have, who don't hunt within 100 miles of the closest wolf and who've never seen a wolf is like chasing a scapegoats shadow.

Instead of doing anything about the UP's real habitat problems, we as a group have PO'd the 80% of non-hunters and now the wolf hunt will likely be on the ballot in 2014. Let's just hope that liberal turnout is low in 2014 due to  all the problems in DC. But the wolf hunt is just a side issue. The bigger issue is groups realizing that if they take hunting issues to the ballot box, they win almost all the time. While many hunters hate the DNR, turning over natural resource management to suburban soccer moms and coffee house hipster dufus types at the ballot box will be the end of our world.

Back to my point-what do we want as a group? More opportunity? How about adding bow season dates?That should be priority #1. Basing "killing" opportunity with real opportunity is the wrong approach, in my opinion. Nobody complained about lack of opportunity when antlerless deer tags were mostly by lottery. It's the "hunt" itself that's the opportunity. Whether one wants to kill 2 fawns with his bow is a choice he can make or if he wants APR's or hunters choice, he can choose where to hunt or what tags to buy. One never has to fill a tag, even on a big 8pt. The tag gives you the opportunity to be bowhunting. But when January 2 rolls around, unless you leave Michigan, your bowhunting opportunity has ended.

In DMU's with low deer numbers, maybe we should be considering more conservative harvest restrictions, not more liberal regulations. Then again, maybe not. That's something we should ask the biologists about.

Maybe in the UP, one should only get to use one buck tag all year? Maybe there should be tags by region, where if you hunt the NLP, you buy a NLP tag and you only get one buck in the NLP, all year?

I'm just throwing things out there, but we need to think proactively about positive changes we want vs basing our groupthink on things we're against. If all we are is against new idea's, all we'll end up with is fewer old idea's that are out of date. I don't think any changes should be off the table, without at least giving them fair consideration.

As far as UP habitat improvement, I just don't see any long term fix that's worth the expense. If habitat work is to be done, I'd suggest doing it and spending the money in the NLP, where more SLP hunters can access it with a 2-3 hour drive and if need be, the yoopers may one day have to swallow the shame of driving south across the Bridge, to access decent deer hunting habitat. Just thoughts.

[Jon Stewart]

Doing what I can afford to do at my place I call my "Field of Dreams".  Had 42 semis of pine trees/chips removed on two 4 acre strips within the pines, spent $10,000 on a backhoe to remove stumps left from the tree removal.  Just finished that up this past summer.  Looking to sell the backhoe and buy a tractor to work up the new small fields and other small spots BUT that just me.  My neighbor on 2 sides could give a rip and I touch some Federal property and, well its just plain government land.

The government in their infinite wisdom planted Autumn Olive.  Works for birds but it is very invasive. I have pockets of that stuff all over the place and am constantly removing the best I can.  That plant is as tough as poison ivy to get rid of.

So reading what everyone has written, I still wonder what the answer would be.  I can't see the government spending a bunch of money on habitat for deer and other game.

Thanks to everyone who posted here.  It is a good and informative thread.

[Bonebuster]

Money...that's what it`s all about.

Crossbows..."millions" wanted them...is it better for bowhunting? Does it generate more money? Sell more tags?

Habitat improvement? Check the difference between STATE and FEDERAL land and check the difference between how the STATE does it versus how the Forest service does it. It is a bonus that logging DOES help wildlife when the clearcuts regenerate...but when they begin to mature, the faster growing PULP wood forests become USELESS to wildlife. Thigh sized Poplar forests are way too common on State land...it is a cash crop. How much CLEARCUT versus SELECT cut do the Feds do versus the state?

I have been to meetings (TB and crossbows) where the public gets to "voice" their opinions and it is all just a feel good measure. I have NEVER had my questions answered as to how the DNR comes up with REAL population numbers. Pellet counts? Bridge surveys? Mail in surveys? On line surveys?
I am NOT the average deer hunter, but I am a citizen, and my questions were never satisfactorily answered. AND they SHOULD be!

In the late 1990`s I was with friends at a meeting in Harrisville when the DNR was revealing their plan about how to deal with TB. In the crowd, a concerned hunter asked the biologist at the podium how much of an effect the coyotes will have on a low deer population...the biologist responded by saying "NONE" and said with complete confidence that coyotes do not prey on deer, and at worst, they may catch a fawn from time to time. The whole crowd was made up of hunters and we all KNEW better...and the meeting was pretty much over from that point on as everyone then KNEW they (the DNR) were out of touch.

Make no mistake...my household had a good season thus far and it is not over. But the effort and EXPENSE has been tremendous. If not for the time off work, and available money, deer hunting would be a thing of the past for me. I assume many others feel the same way. It is VERY common topic of discussion.

A few pages back, someone asked "what do we do?"
Trust in what the state is doing? I for one am not fooled...it is a money grab, and the whitetail is a very resilient commodity. I truly mean no disrespect to anyone...my decisions are not made by emotion alone. And I know many other citizens feel the same as I do.

[Mojostick]

Please don't take this the wrong way, but it was likely the group of hunters that were out of touch.

While predators do take deer, and coyotes are #1 in fawns/deer followed by bobcats (oddly enough), then bear, then wolves with the fewest fawns/deer killed, it's one dimensional and counter-intuitive to assume that the predators hurt hunter success.

Deer populations are not a zero sum game. We cannot stockpile deer by killing coyotes or banning "doe tags".. Counter to conventional wisdom, predators could provide MORE deer sightings. If predators take some of the young and weak, it can avert a larger winter die off, which would impact the entire herd, even the otherwise healthy adult deer.

As mentioned, we cannot stockpile deer, especially in cruel environments like northern Michigan. If a habitat can support only 30 deer per mile, then winters will average that out, sometimes by killing far more deer than a winter otherwise should. That's the negative many hunters never see.

Now, we can slightly alter age class, like with APR's, but all that's going to do is shift the bulk of the harvest from 1.5 year old bucks to 2.5 year old bucks. The key is to have stable populations, in balance with what the habitat can support. The days of boom-bust-boom-bust has done decades worth of needless harm to our northern forests. It will take 20 more years to recover from the 1990's damage done.

Here's a good read on the impact of predators...

Many deer hunters tend to believe that every deer killed by a predator results in one less deer available for a human hunter to harvest. Research has found the truth to be more complicated. Predators do not, in fact, always reduce the population growth rates of prey.

Biologists use the terms "compensatory" and "additive" to describe the impact of predation on any given wildlife population. If predation is "compensatory," it means the total number of prey to die in any given year does not change as a result of predation. It means the predators remove the number of animals that would have been lost anyway to other causes.

If predation is "additive," then the predator is killing prey animals that otherwise would have survived the cycle of seasons. In these cases, the predator is slowing the growth of the prey population, or in some instances, causing that population to decline.


Here's an excerpt from biologist C.J. Winand...

The word coyote is an Indian term, which means God’s dog. Native Americans gave the animal reverence and admiration. However, white man has waged war on coyotes. The case could be made that no other animal in North America has withstood more intense efforts by man to wipe them out, than coyotes.

Even today’s modern hunters curse the coyote because they take deer. The fact is, coyote do take deer, but the question is, “How many?” Do coyotes really compete against hunters, thus negatively hurting our hunting opportunities? Are there any states importing coyotes to control burgeoning deer populations? These answers have been determined through scientific research.

There is a lot of controversy among hunters, who insist that their state wildlife department has imported coyotes. Although most of this is simply based on emotions, one fact is clear, before any state imports animals across state lines they must have proper permits. I know of NO documentation to support such claims. And believe me, no state wildlife agency would ever jeopardize any kind of funding for such a project.

If the states did not break any laws, “Where did the Eastern coyote come from?” The answer to their establishment in the East is

 
In some areas of the Northeast, bowhunters are often faced with the dilemma of choosing between tracking too soon and losing the deer to coyotes.

still speculative. Theories suggest that the present day eastern coyote was probably a cross with a timber wolf that dispersed across Canada into the eastern US, a cross between a feral dog or was the same animal we used to call the brush wolf. Genetic studies lean toward cross-breeding with wolves as the most likely reason why we have coyotes in every state east of the Mississippi River. Research has proven that coydogs simply don’t pass the natural selection test and only survive a generation or two.

Coyotes are omnivores, which means they will eat almost anything. One research project in Texas showed that predators, primarily coyotes were responsible for 60 percent of all fawn deaths in one year. It should be pointed out that the study area experienced severe drought for two years. During the third year, rainfall amounts were back to normal and fawn survival increased up to 80 percent. This study basically proves that given adequate cover or hiding places (which most of the US has), coyotes will NOT impact a deer herd.

Hunters also point out, they actually see coyotes with deer parts in their months or they notice the amount of deer hair in a coyote’s scat. The real question is, “Are these animals the coyotes eating already dead?” Being an opportunistic critter, chances are the deer are already dead or carrion. From an energetics point of view, “Why would you chase a deer half way across the county when you could eat a road kill?” The answer is, no animal would waste the energy.

Where deer densities are too high and hunting pressure light, the coyotes are actually doing the deer herd a favor by taking out a few deer. On the other hand, where we have deer populations less than 10 deer per square mile, coyotes may have a negative impact. But, there are very few places in the country where this exists. Do coyotes negatively effect our deer herds? The answer is generally NO! In fact, in the big woods with an average deer herd and normal precipitation, I doubt whether it’s even measurable. Do coyotes take deer? Yes, but there is no doubt we loose more deer to road kills, birthing complications, disease, abdornmalities, etc. than coyotes would ever take to significantly effect our hunting opportunities.

CJ Winand is a whitetail biologist from Randallstown, MD. He is a staff writer for Bowhunter as well as Deer and Deer Hunting Magazine.

[Mojostick]

I hope I haven't ruffled any feathers here, that is not my intention. I hope people can consider what points I'm trying to make on a pretty complex situation and for those who disagree, then we'll agree to disagree for now.
I'm going back to trad bow talkin'!    

[Bonebuster]

Whenever someone says they "KNOW" for sure and are "certain" and "no doubt"...and they are rarely or NEVER in the woods...well take it for what it`s worth.

And I STILL have never gotten and answer as to HOW the DNR knows ANYTHING about the modern population in REAL numbers...not made up ones or excuses for a poor deer kill because it rained on opening day.

[no]

This could be NY

[Mojostick]

From Michigan State University...

 http://deer.fw.msu.edu/management/assessment.php/


Assessment of Deer Populations
 
Successful deer management requires some form of population assessment so that population objectives and goals can be formulated.  Management agencies assess deer populations using a variety of methods.  Some methods, including counting of deer and utilizing intensive surveys to estimate populations or identify trends are often labor intensive and expensive.  Other estimation methods are more easily implemented, yet perhaps less accurate, and may not provide the reliability or precision desired by some agencies and stakeholders.  Other assessment techniques based on specific outcomes such as hunter and landowner satisfaction, or measurements of deer impacts on agricultural crops, forest regeneration or native plant communities can also be used.  The Michigan DNR, like most agencies, relies on a suite of assessment methods to provide information needed to make management decisions.

Voluntary Deer Check
 Michigan’s voluntary check system gives the DNR the opportunity to collect biological and physical data from a sample of the harvested deer. This data is used in a variety of formats to monitor the size, composition, and health of the deer herd.  The percent of harvested deer checked varies across years, seasons, and regions, but has recently averaged around 10 percent of the total deer harvest. Wildlife management agencies in some states utilize mandatory deer check or telephone or internet based deer check systems, but in many instances, little to no biological data are collected from harvested deer.

At the check station, a trained DNR employee or volunteer records the age, as determined by the tooth wear patterns, and sex of the deer, the location and season of harvest, and the size of the antlers for bucks or the lactation status for does. Voluntary deer check stations also provide the opportunity to monitor the deer herd for diseases as some hunters are asked to submit samples to be tested for bovine tuberculosis and chronic wasting disease. As a secondary benefit, for many hunters, a visit to the deer check station represents a rare opportunity to discuss issues, share their thoughts and experiences, and ask questions as they directly interact with DNR personnel. This also provides valuable anecdotal information to DNR personnel regarding hunter opinions and impressions of deer hunting and management.

Mail Survey
 The annual deer harvest mail survey uses a statistically based, stratified sampling design to develop estimates of the number of antlered and antlerless deer harvested, the number of hunters pursuing deer, and the number of days hunters spent pursuing deer.  This information is collected by county, Deer Management Unit (DMU) and season.  The survey is sent to a randomly chosen sample of people who purchased Michigan deer hunting licenses.  The survey asks hunters to report where and for how many days they hunted and to report the number of antlered and antlerless deer they were successful in harvesting.  Although only a sample of hunters receive the mail survey, all deer license buyers can report their hunting effort and results online.  The harvest survey data helps to assess the effects of regulations on hunting seasons and to assess the potential effects of the hunting season on the deer population.

Sex-Age-Kill (SAK)
 The primary method for generating deer population estimates in Michigan is the SAK technique.  Data taken at deer check stations includes sex and age composition of the deer harvest while data acquired by the post-season mail survey provides an estimate of the buck harvest for that season.  This data is used to reconstruct the pre-hunt deer population.  The key assumption for SAK is that the buck kill should go up when increases in the buck population occur and should go down when decreases occur.  To minimize effects of assumptions and biases on SAK population estimates, local biologists may adjust standard SAK estimates based on local knowledge of hunting conditions and generally only biodata collected from deer harvested within the firearm season is used.

Winter Severity Index (WSI)
 The Michigan DNR implemented a technique to index the severity of winter weather conditions starting in 1964 in the UP and 1986 in the LP.  This WSI was composed of air chill and snow hazard ratings.  The current WSI uses data collected hourly at automated weather stations located throughout Michigan and the surrounding area and reported by the National Climatic Data Center.  Temperature, wind speed, and precipitation data are downloaded and calculations performed on a weekly basis from November 1 through April 30.  The WSI values from individual stations can be averaged together to give a regional perspective on winter severity. Weekly index values may be plotted to identify the pattern of severe weather events throughout the winter season (such as the very early or very late peaks in severity that tend to have the greatest impact on deer) or they may be summed throughout the year to track the cumulative effect of the winter weather on deer (a less informative approach).

Pellet Surveys
 Hunters frequently use the presence of pellet groups (deer scat) to assess whether areas are occupied or unoccupied by deer, or as a measure of deer abundance. Pellet surveys are best used as an index for tracking annual changes (increases or decreases) in deer density and to help evaluate other population indices and estimates.  Pellet surveys previously conducted in much of northern Michigan on a regular basis have become less frequently implemented over fewer areas.  The most recent implementation was limited to use in the western UP to assess trends identified by other methods, and is no longer commonly used.

Observations, Spotlight Counts and Aerial Surveys
 Spotlight counts and aerial surveys offer several advantages over daytime observations.  These methods are sometimes implemented in surveys in order to assess trends in local populations.  Rather than being conducted as highly structured, formal surveys, these efforts often complement other sources of knowledge or information.  They allow biologists to draw inference regarding distribution of deer on different land ownerships or distinct areas within a larger area at which other data are summarized.

Deer Camp Surveys
 Many deer hunters in the UP return to the same “permanent” deer camps during the November firearm season.  Camps are typically occupied by five to ten individuals who hunt on the same parcels of land year-after-year.  Deer camps tend to keep records of their deer sightings and kills over the years or are willing to do so if they believe the resulting information can help manage the deer herd.  The DNR devised a cooperator deer camp survey that is distributed to select camps during the 16-day firearm season.  The survey allows hunters to provide their assessment on local deer herd levels and the quality of hunting.  This survey has been conducted in the western UP since 1994 and the eastern UP since 2003.  

The deer camp survey has several objectives:
•Assess deer herd size compared to past years (more, same, less) based on the number of deer seen, harvested, and camp opinions of deer herd trend.
•Monitor doe-to-buck and fawn-to-doe ratios from hunter sightings.
•Assess the quality of hunting based on hunter success rates and their written comments.
•Monitor trends in sightings of select furbearer species by deer camps.  
•Detect and address emerging deer management issues based on written comments submitted by camps.

The information resulting from this survey provides an early and localized view of deer herd size, trend, and hunter satisfaction.  This survey, while hindered by small sample sizes in some deer management units, provides information immediately following the deer season.  Thus, it fills a gap in information until other survey data are available.  

Deer Tagging
 Trapping and tagging deer during the winter months can provide information on seasonal migrations.  Deer have been tagged for over 50 years in Upper Michigan to catalog the migration patterns for deer in different wintering areas.  Objectives of tagging studies include: determining the distance and direction of seasonal migrations and measuring the size of the total annual range for deer associated with each wintering area.  Trapping and tagging are done during the months of January through March when deer were most concentrated and natural foods are in short supply.  Subsequent observations of tagged deer by the public are provided to the DNR.  Observations of tagged deer include live free-ranging deer, hunter-harvested animals, and deer struck by vehicles.

Other Indicators
 In addition to formal population estimates, indices and measures, other factors are considered when evaluating deer populations. Local wildlife biologists monitor deer-vehicle collisions, crop damage and forest regeneration issues as well as hunter satisfaction and hunter success rates. These indicators, when tracked over time and evaluated in the context of other changing factors can provide insight into local deer population trends.

In summary, precisely estimating population size of free ranging white-tailed deer at the local, DMU or statewide level is difficult. Conditions vary across the state and no known single population estimation technique can be successfully applied statewide. By applying a consistent technique (SAK), in combination with consideration of a variety of locally appropriate measures and factors, biologists in Michigan can provide a reasonably accurate population estimate that is useful when making deer management decisions and evaluating population goals and objectives.

[Mojostick]

Here is a good explanation of SAK from WDNR...

 http://dnr.wi.gov/wnrmag/2009/10/deer.htm


While the Sex-Age-Kill (SAK) calculation has used the same factors since the 1960s with some modifications, there are misconceptions about how the agency arrives at its annual population estimates. In most areas of the state, "the count" is made by compiling and analyzing the mandatory stubs provided by hunters registering each deer harvested in each Deer Management Unit (DMU). The stub tells the location and sex of each deer harvested and an age is determined for a representative sample of the registered deer. This data is combined with information gathered during field studies to calculate an estimate of what the deer population was like when the hunting season began.

Since the early 1960s, the DNR has used a statistical formula called the SAK model to estimate, not count, Wisconsin's deer population. Information from hunter harvests is the foundation for making this estimate. There is no way to duplicate the details about the deer herd that more than 600,000 hunters help us capture each year, and the SAK method capitalizes on this power. The specifics that hunters provide when registering their deer are the most important parts of the deer population estimate.

SAK incorporates the registered buck harvest and other data collected by hunters and field biologists using a series of equations developed with decades of sound population data to estimate the size and makeup of the buck, doe and fawn populations as they were prior to the hunting season.

SAK in detail

Let's look at the SAK method in more detail. There are several parts to the SAK model: the buck harvest, the buck harvest rate, the age structure of bucks and does harvested (the adult sex ratio), and the fall fawn-to-doe ratio.

The buck harvest is the combined registered buck kill from all seasons and includes bucks taken using damage permits. In Wisconsin, this harvest data comes from the registration stubs hunters have provided since 1953. At registration stations, DNR staff and volunteers age a representative sample of deer brought in by hunters – more than 20,000 animals are aged each year. These data are critical for accurately estimating the buck harvest rate and the adult buck-to-doe ratio.

The buck harvest rate relies heavily on the data collected by aging bucks harvested statewide and on past research gauging the proportion of all bucks taken during legal hunting seasons. In heavily hunted populations, about 90 percent of buck mortality is due to legal harvest. In more lightly hunted populations, the legal harvest may account for only 60 percent of buck mortality. The buck harvest rate is generally higher in the southern farmland areas of Wisconsin where the deer range is more fragmented and hunter densities are higher than in the extensive northern forests, although this has been changing recently.

The adult sex ratio of adult does to bucks in the fall population is estimated by measuring the proportion of yearling does to yearling bucks from the harvest data. This is another factor that relies on the information we gather when aging deer at the registration stations. The comparisons year to year show that does live much longer than bucks.

Let me show how this factor is used. Hypothetically, if buck and doe fawns were born in approximately equal numbers and if bucks were to die about twice as fast as does do, then the proportion of yearling does in the harvest would be about twice that of yearling bucks. In this example, the adult sex ratio would be about 2:1 – two does per buck. In reality, there are between 1.2 and 2.3 adult does for every adult buck (at the start of the hunting season). Generally, there are more does per buck in southern Wisconsin where hunting pressure on bucks is higher.

The fall fawn-to-doe ratio is created by data collected by department staff and volunteers who keep records of deer observations from July through September. Biologists, foresters and many other volunteers record the number and type of deer they see and the DMU (management unit) in which the observation was made. The compiled data are used to estimate the yearly fawn production per doe around the state. That number is multiplied by the number of adult does to estimate the fawn population.

Essentially the number of bucks in the herd is estimated by dividing the number killed during the hunting season by the harvest rate. The doe estimate is made by multiplying the number of bucks harvested during the deer season by the ratio of adult does to adult bucks. The number of fawns is judged by multiplying this doe estimate by the fawn-to-doe ratio. Adding these three totals together provides an estimate of the deer population on the landscape before the hunting season opened.

To estimate the number of deer remaining after the hunting season, the total harvest is multiplied by 1.15 (to account for 15% of the population that we estimate may die from wounds or poaching mortality). That total is subtracted from the pre-hunt population to form a post-hunt population estimate. Those post-hunt estimates are built into the overwinter goals for the herd.

What SAK can and can not do

SAK is a time-tested model that has been independently reviewed for reliability and precision several times. According to outside experts, the amount of data collected and the way SAK is used make Wisconsin's deer population estimate one of the best in the nation. The SAK uses harvest information from hunters to estimate the deer population at two points:
1.pre-hunt (September 15) and
2.post-hunt (February 1)

The information used to form the SAK is robust because it is re-calculated every year from data collected when deer are harvested by more than 600,000 hunters. However, this model does have limits. SAK is not designed to predict how many deer will be in Wisconsin woods and fields before the fall hunting season begins. The harvest data can only be used to estimate the pre-hunt deer population in hindsight.

Long-term averages of historical data are used to estimate how deer herds change between February and September. Indices like the Winter Severity Index estimate how well the herd survives under various winter conditions. These averages are applied to project what may be expected to happen in any given year. Predicting the fall status of the herd is less accurate since these predictions are based on historic data on herd growth and are influenced by many factors, including winter weather and spring weather conditions that affect fawn survival.

For those of you who are a bit more interested in mathematics and statistics, we'll delve into the SAK a bit deeper. The precision of SAK decreases as the sample size decreases. So the population estimates are much more precise and accurate for larger Deer Management Units covering a larger area. The SAK cannot estimate the deer population on a single parcel of property. This can be frustrating to hunters as the average deer density calculated by SAK for a whole management unit is not likely to be reflected in what they see right under their treestands. Deer are not distributed evenly across the landscape and their travel patterns change with time.

SAK also does not directly estimate the impact of predators on deer populations. However, since the estimate is valid immediately prior to the hunting season, the impact of predation is accounted for in the population estimates.

[Mojostick]

Here is some more, a bit of a rehash. But hopefully this answers the question of how they establish the estimates...


MDNR Estimating Deer Population Numbers

by MS.com staff on August 26, 2011


Scientific estimates of wildlife numbers and information about population trends (increasing, decreasing, or stable) are necessary to successfully manage wildlife. For more than 50 years, the Michigan Department of Natural Resources (DNR) has worked very hard at estimating deer population numbers. Each year, wildlife biologists use this population estimate to adjust hunting season rules and regulations to meet the DNR’s long-range deer management goals to.…

Maintain a deer herd that is in balance with its habitat and that yields healthy fawns, does and bucks;

Maintain a quality deer herd to meet the social, economic, and recreational demands of the public, while considering public safety and the carrying capacity of other native species, native plant communities, agriculture, horticulture and silviculture; and

Maintain a quality deer herd to provide diverse quality recreational experiences for those wishing to hunt deer and those wishing to view them.

White-tailed deer populations, like other wildlife species, fluctuate in size from year to year, as well as from season to season. Annually, they reach their highest number by early summer, following the birth of fawns. Predation, disease, vehicle-deer crashes, hunting harvests, and winter losses due to starvation reduce their numbers during the rest of the year. Various survey techniques have been designed to assess these losses and provide wildlife managers with information to estimate the size of Michigan’s deer herd. These techniques fit together like the pieces of a jigsaw puzzle all of them are needed to see the entire picture. Following is a brief description of the time-tested surveys that the DNR has relied upon for managing Michigan’s white-tailed deer.

Deer Harvest Surveys

Hunting harvest information is the foundation for monitoring the deer herd. Hunting is the major source of population reduction. Mail surveys, rather than mandatory registration, are used to estimate the legal deer harvest each year. Following the 1999 deer season, nearly 1-out-of-16 deer license buyers were mailed a survey questionnaire requesting information about their hunting season results. These scientifically random samples of license buyers provide reliable estimates of the deer harvests by county. Hunter success and the ratio of young to older-aged deer in the harvest provide wildlife biologists with additional information about the status of local deer populations, such as population growth and sex ratios. Scientists around the world recognize our mail survey techniques for their excellence.

Summer Deer Observations

For nearly 70 years, DNR wildlife biologists, conservation officers, foresters, and other field employees have recorded the numbers of deer seen during daylight hours during the period from July 1 to October 31. Changes in sighting rates (the number of deer seen per hour of effort) reflect changes in the deer population. Summer deer observations provide wildlife biologists with one measure of fawn production that is critical for estimating population size. Deer observations are also useful for forecasting upcoming hunting seasons, identifying areas where deer numbers are changing, and for assessing the sex and age composition of local deer populations.

Check Station Data

Last year, DNR employees checked and recorded physical data for approximately 43,000 hunter harvested deer brought to highway deer checking stations and DNR offices. Experienced deer “agers” determine the sex and age of each animal, count antler points, measure antler beams, and check the general condition of each deer. Deer are also examined for bovine tuberculosis. Antler points and beam diameter measurements provide biologists with an index of the physical condition of local deer herds. Age and sex information for harvested deer is compared with similar information obtained from summer deer observations, to assure that the best available data are used for estimating the deer population size each year.

Traffic Survey

The sole use of the deer traffic survey is to provide an early estimate of the firearm season deer harvest. Michigan’s strong deer hunting tradition has always captured the interest of news reporters who are eager to report the deer hunting season results. DNR employees count deer on vehicles as they pass by observation points along the four major north-south highways in the Lower Peninsula. Deer “agers,” who are stationed at deer checking stations at highway rest areas, help with this estimate. They determine whether deer are visible to highway counters. The traffic survey results are then adjusted for those deer that are not visible to highway counters. The results of the deer traffic survey closely match with mail survey results, which are not available until spring.

Pellet Group Surveys

DNR field employees are busy with deer pellet surveys during the spring season. This survey provides a useful index of deer distribution and abundance from year to year in the northern-forested areas of the state. Pellet group surveys do not work well in areas where intensive agricultural activities disturb evidence of deer. Since 1950, field employees have counted pellet groups along random survey courses to determine the relative number of deer within a defined area. These counts are generally expressed as deer per square mile.

Dead Deer Searches

Dead deer searches are done in conjunction with pellet group surveys. Teams of Wildlife personnel count the number of dead deer they locate while walking pellet survey courses. When a carcass is found, a determination is made whether the loss occurred during early or late winter. Over-winter loss is a major source of non-harvest mortality to deer on the northern fringe of their range. The results of dead deer searches are used with pellet group surveys to estimate spring deer populations.

Car-Deer Crashes

A common deer population index in the Midwest is the number of car-deer crashes reported to law enforcement officers. Several research studies from across the country indicate that car-deer crashes are related to road densities, traffic volumes, and deer densities. The Michigan State Police and the Michigan Department of Transportation maintain data on the number of car-deer crashes and traffic volumes. Recent findings by Michigan State University demonstrate the usefulness of these data to wildlife managers since a correlation exists between county car-deer crashes and the buck harvest. Car-deer crashes are also used to estimate additional non-harvest mortality.

[Mojostick]

Here's a good explanation of the SAK model from Michigan State University...

The Sex-Age-Kill Model
 By Justin S. Hall

 Last month I looked at the ways that the Michigan Department of Natural Resources collects the data that is used to estimate the deer population. Two different types of data collection were discussed. Indices, which reflect trends in populations, such as the summer deer observations, and samples, which estimate parameters of the population, such as the pellet counts. Indices can only give an indication of whether the population is moving up or down while samples can potentially be used to give an estimate of the size of the population.

 One of the main ways that the DNR estimates the population of deer is by using a mathematical model known as the Sex-Age-Kill model. Models can be very simple or very complex but at their heart they are merely a way to quantify what you observe. In the case of modeling the deer population of Michigan it is important to look at what is easily observable. In Michigan we harvest a lot of bucks each year in the deer seasons. Since we kill a large percentage of the bucks each year and we can put a good estimate on the number killed, estimating the total number of bucks seems like a good place to start for estimating the overall population. Then, if you can get an idea of how many does are out there for each buck, you can estimate the number of does based on of the number of bucks. Finally, if you can get an idea of the average number of fawns per doe at the start of hunting season you can estimate the total number of fawns based on the number of does. Add all this up and you have an estimate of the deer population. This is basically what the Sex-Age-Kill model does.

 The Sex-Age-Kill model was adapted from fisheries population models for use in deer population modeling in the late 1950’s and early 1960’s. Much of the development was done here in Michigan by Lee Eberhardt of the Michigan DNR. The methods for estimating the number of bucks, both those that are harvested, that die and are not retrieved, and those that survived, along with estimating the buck to doe ratio, and the fawn to doe ratio, are all based on scientific studies conducted in Michigan and other states. Since the early 1960’s, this approach and similar harvest-based models have been adopted as the primary deer population estimation technique in much of the Midwest.

 So how does the Sex-Age-Kill model work? Let’s say that you own a hunting camp of 640 acres, one square mile. You and your friends are the only people that legally hunt deer on that square mile and you live on the property year round and you like to spend a lot of time observing the deer. Last hunting season you and your friends killed four bucks and three does on the property. You took them into the DNR check station and they aged them for you. Three of the bucks had small racks, a spike, a forkhorn, and a nice 6 point, and the largest buck had a wide rack with eight points. The biologists aged the first three bucks and one of the does as 1-½ year olds. The large buck and the other two does were aged as 2-½ year olds. As you were leaving home one day you noticed a dead buck in the ditch along the road on the east side of the property which you are pretty sure wandered out of your woods. So now you want to get an idea of how many deer there will be on your property next year so you know how many friends to invite.

 We’ll start by figuring out the number of bucks at the beginning of hunting season. You already know that there were at least 4 bucks since those are the ones you harvested. You found one more dead. We don’t know how many deer died for other reasons, like the one you spotted along the road, but studies have shown that 85 to 90% of bucks will die by legal harvest. This is known as the recovery rate. That leaves 10 to 15% that die from other causes. How many got away? We know that some do survive, otherwise you would never have gotten that 2-½ year old. At this point we rely on research from New York and Michigan that shows that the percentage of 1-½ year old deer in the harvest is approximately equivalent to the percentage of bucks killed in the harvest. In Michigan the percent yearling bucks in the harvest is about 70%, and it is highest in the southern lower and lowest in the UP. First we determine the total percent mortality of bucks.

 Percent Mortality = Percent Yearling Bucks x Recovery Rate

 To determine the percent mortality we multiply the percent yearling bucks by the recovery rate. We multiply by the recovery rate to take into account the non-harvest mortality. So, on your square mile 3 of the 4 (75%) bucks killed were yearling bucks.

 Percent Mortality = 75% yearling bucks x 90% recovery rate

 Percent Mortality = 67.5%

 We then determine the total number of bucks by dividing the buck harvest by the percent mortality.

 Total Number of Bucks = Buck Harvest

 Percent Mortality

 Total Number of Bucks = 4 adult bucks

 67.5% mortality

 Total Number of Bucks = 5.9 adult bucks

 (Now of course you can’t have 0.9 deer on a square mile, but if you look at 10 square miles there will be 59 bucks.)

 So, we know approximately how many bucks were on your property, now we need to use that information to determine the number of does.

 To determine the number of does we first need to know the adult sex ratio. If the buck harvest is indicative of the bucks out there, is the doe harvest indicative of the number of does? Not necessarily. First, the number of does harvested is limited by the number of doe tags available and by the willingness of the landowner and hunters to harvest does. However, we can use knowledge from other researchers that shows the ratio of yearlings in the harvest can be used to determine the adult sex ratio. In determining the adult sex ratio it is assumed that there are about an equal number of 1-½ year old does to the number of 1-½ year old bucks.

 Adult Sex Ratio = Percent Yearling Bucks

 Percent Yearling Does

 75% of the bucks you harvested were 1-½ year olds and 1 of the 3 (33%) does you harvested was a 1-½ year old.

 Adult Sex Ratio = 75% yearling bucks

 33% yearling does

 Adult Sex Ratio = 2.3 does per buck

 Using that sex ratio and the total number of bucks we can now determine the total number of does.

 Total Adult Does = Total Adult Bucks x Adult Sex Ratio

 Total Adult Does = 5.9 adult bucks x 2.3 does per buck

 Total Adult Does = 13.6 adult does

 The last thing to do is to estimate the number of fawns. As you wandered around the property you noticed some does with twins and some had single fawns. You also noticed that a couple of young does didn’t have any fawns and you also came across a couple of dead fawns in the woods. The DNR check station data for your area shows an average of 0.6 fawns per doe in the harvest, this seems to agree with your observations on the property. The total number of fawns equals the total adult does multiplied by the fawn to doe ratio.

 Total Fawns = Total Adult Does x Fawn to Doe Ratio

 Total Fawns = 13.6 adult does x 0.6 fawns per doe

 Total Fawns = 8.2 fawns

 To determine the total population on your square mile all that is left to do is to add up the number of bucks, number of does, and number of fawn.

 Overall Population = Number of Bucks + Number of Does + Number of Fawns

 Overall Population = 5.9 adult bucks + 13.6 adult does + 8.2 fawns

 Overall Population = 27.7 deer

 Translate that to the land around your hunting camp and you have about 28 deer per square mile.

 28 deer represents a mathematical estimate of the number of deer that were on your square mile on October 1st, just before hunting season. It seems strange that you would estimate the number of deer before the hunting season after the hunting season is over but you can then adjust the number for the number of deer you killed. So, subtract the seven deer that you killed and you still have about 21 deer on the property. You also need to subtract the number of deer that are killed by means other than harvest. You add 10% of the number of bucks harvested so subtract another 0.4 deer leaving you with approximately 20 deer to start the herd for the next year. If we examine those 20 deer more closely we see that 2 bucks survived, 10 does survived, and 8 fawns survived. Since fawns are evenly split between buck fawns and doe fawns, come hunting season next year there will again be 6 bucks on the property, and 14 does, one more than last year, so the herd is slowly growing.

 Due to the effect that changes in habitat from year to year can have on deer distribution, this model this model works best for larger areas than on the individual square mile. For this reason the DNR collects data from all over the state and uses information from much larger areas (county to several counties) to incorporate into these models. But just as an example, if you were to take your 28 deer per square mile and multiply it times the approximately 56,000 square miles in the state you would come up with around 1.5 million deer in the state. Of course deer are not evenly distributed across the landscape and some areas will have more deer than your area and some will have less. The DNR estimates for the county or counties that includes your area won’t necessarily represent your particular square mile but will be the average per square mile for that larger area.

 If you have a good idea of the numbers for your particular area, or you think one of my example numbers should be changed, for instance perhaps the sex ratio should be different, I would encourage to you to put in those numbers and see how they effect the population numbers.

[ChuckC]

again.. thank you for this information.

ChuckC