Does anybody know the exact method of how they are counting the deer on our units? I've heard they just count an area during the rut after the hunts that has deer on it and then compute that density across the whole unit. I really really hope that's not true. There are lots of areas void of deer, if that is the model they need to change it about 40 years ago. If any biologist are on this website please speak up and inform us.
To get to the meat of what your question was. The DWR does not count deer to get a population number. They estimate the population using population models that use several key collected data points. I shared some info on that in post #12 if you want to go back and look at that.
I know that for several people that have commented on this thread, what I'm going to write below will mean nothing and will not help their understanding at all, but hopefully to somebody out there it will be informative. Hold on to your butts cause this is about to get wild and technical.
During November/December the biologist classify deer. They count how many bucks, does, and fawns they see. That isn’t to try and count how many are on the unit, but to get buck/doe ratios, fawn/doe ratios and fawn/adult ratios. The total number they count is irrelevant as long as they get a big enough sample size. The ratios are important because that’s part of calculating the growth rate of the population for that year. After the hunts are over, they get hunters surveys back so they know how many animals were harvested. They calculate survival rates from the does and fawns they have collared around the state. Once they have all the data, they run population models on a computer. I’m not a mathematician so I don’t understand the details of that. (Also here’s a plug for spending time with your local biologist to ask them this stuff!). The models kinda work backward using the data collected. Using the survival rate of does and fawns, growth rate, harvest data and the ratios of bucks/does and fawns/does for the last couple years, the models estimate how many animals are out there for that unit in order for all the data points to be true. The models use many years of data to estimate what a single year’s population estimate is.
I don’t know how to write a perfect example, but here’s the basic idea. If you harvest around 500 bucks from a unit multiple years in row, and at the end of the hunts the buck/doe ratio is still whatever number. You can infer that there’s enough females to produce 500 surplus bucks each year. The bucks don’t come from thin air. If you have the number of bucks harvested over multiple years and know the buck/doe ratio over multiple years, you know there’s been does producing enough bucks for that harvest to happen. So the model uses the survival rates, growth rates, buck and fawn/doe ratios, from the past couples years to determine how many females it would take based on the past couple years data to have the harvest of bucks that happened over multiple years.
SOooooooooooooo lets do a basic model!!! It was stated in this thread that the Beaver doesn't even have 1200 deer on it. Lets do some rough work through that. (All the numbers I'm using are from the harvest data from the DWR's webpage and the hunt planner website and what general survival rates are for mule deer.) The buck/doe ratio has averaged 15/100 the past three years. The fawn/doe ratio was around 48/100 and the fawns/adults was 42/100 at least from the annual reports online.
So if we take 1200 deer that somebody thinks is on the unit at a 42/100 fawn/adult ratio, that would give us around 354 fawns and 846 adults. If the buck/doe ratio is 15/100, that gives us around 110 bucks and 736 does. If 60% of the fawns survive and make it through the winter (that's a really good number) and the ratio of buck fawns to doe fawns is 50/50 there will be 106 additional yearling bucks next year and 106 yearling does. Adult survival is around 85%, but lets say only 10% of our population dies. We'll lose 73 adult does and 10 of the adult bucks giving us 663 2+year old does and 100 2+year old bucks by next hunting season. Adding the 2+year olds and yearlings gives us 769 adult does, and 206 adult bucks at the start of hunting seasons. The 2+year old does will have had fawns, so there will be 318 fawns with them if the ratio stays around 48/100. Our total population to start the hunting season would be 1,293. In order to end the hunting season with a buck/doe ratio of 18/100, you could only harvest 68 bucks.
In 2020, 535 bucks were harvested on the Beaver. In 2019, 745 bucks were harvested.
Do you see how there's no way that a population of 1,200 deer could produce enough bucks to have multiple years of harvesting more than 500 bucks? The Beaver has had more than 500 bucks killed on it for 10+ years. You'd have to have waaaay more females to be able to harvest 500+ bucks year after year and still have enough bucks to have a 18/100 buck/doe ratio after the hunts. If we work backwards and this is rough because its just me doing some math and I used very high survival rates for both adults and fawns, but if with 1200 deer in our model we were only able to harvest 68 bucks, then to be able to harvest the 535 bucks
that were actually in fact harvested there was likely a population around 9,553. The most recent population estimate on the Beaver is 10,300. So just me and my looking up data I was able to get pretty close to what the DWR got, but they were using the exact data they've collected from classifications, harvest reports and collars to get survival rates for the does and fawns. Congrats if you've made it this far you know how to model a population and we estimated the Beavers deer population pretty close to what the DWR did.
I can’t speak to exact accuracy, but they use this method because studies done on calculating population sizes have shown it’s a relatively accurate and cost effective way to estimate populations. Any method of trying to determine a population is an estimate. Even flying in a plane because you never see every animal (they know that through mark/recapture studies, google it). So they picked a method that was they felt was the most cost effective and accurate way to estimate the population.
So there’s that and hopefully that helped answer your original question. If not, I recommend calling your nearest DWR office and asking for your local biologists number and then going out with them to classify deer and ask them whatever questions you might have about it.