A couple of weeks ago, I wrote about the impacts of habitat quantity and quality on white-tailed deer harvest rates. Habitat quantity does not necessarily impact the harvest rate itself, but a property that provides a smaller amount of habitat must harvest fewer deer than a property that provides a larger amount of habitat in order to keep the deer population on the ranch stable. Habitat quality, however, can vary between properties that provide the same quantity (in acreage) of deer habitat, which in turn impacts the health and productivity of the ranch’s deer population.

Habitat quality impacts deer harvest rates because herd productivity will vary between properties. If deer density is held constant, deer on a property that provides good habitat will be in better condition than deer on poor habitat. This superior body condition can be measured through increased body weights in animals and improved antler quality in every age class of bucks. Today, I will discuss how fawn survival, as effected by deer density and the buck to doe ratio, can significantly impact the annual harvest of white-tailed deer populations.  

Most hunters understand that fawn production is an important component of white-tailed deer management, but they fail to realize how annual fawn survival directly impacts the number of deer harvested each year. Fawn production (the number of fawns born) is difficult to measure, but fawn survival is not. A good estimate of fawn survival can be collected annually using daylight deer surveys in late summer and early fall.

Every hunter wants to see bucks—and we all know they start as fawns—but once a property reaches its ideal carrying capacity, proper deer density, and buck to doe ratio, then it is fawn survival that ultimately determines the number of deer that should be harvested each year. A year with low fawn survival will not add many animals to the population, so not many adult bucks and does should be harvested. On the other hand, a year with high fawn surival means many new animals have been added into the population, so hunters must remove deer to maintain the property’s deer population at the proper deer density.  

A healthy deer population will more productive than a stressed deer population. As a result, reproductive success, as measured through fawn survival, can be a good measure of the health of the local deer herd. In turn, good reproductive success is often reflective of good deer habitat. Habitat conditions will vary annually based on precipitation, but white-tailed deer found on good habitat will almost always have higher fawn survival than deer found on poor habitat, regardless of the year. And all this stems from habitat quality, which determines the condition of individual deer living on the ranch. Healthy does produce more fawns and healthy fawns have higher survival rates. It really is the cycle of life.

Many hunters fail to realize that fawn production is strongly tied to habitat quality and the body condition of individual deer. Case in point: Think about a property that has a good number of deer, but the number of bucks is relatively low. The guy managing the property thinks that not shooting does will eventually lead to more bucks. But it doesn’t work. What’s going wrong? Well, a bunch of unhealthy deer on poor habitat will not produce many fawns.

The typical problem that exist on properties such as in the example above are that there are simply too many deer! If a property can only support 50 deer and there are 100, then fawn survival will be low. It wouldn’t matter if the buck to doe ratio was 1:1 or 1:5, if there are too many deer fawn survival will be low. The proper remedy in the example above would be to remove a good number of the does so that the remaining does could raise fawns, thus leading to higher fawn survival. A 10% (4) fawn survival out of 40 does is less deer than a 60% (12)fawn survival out of 20 does! That also means 6 new buck fawns instead of only 4. This is just a simple example, but you get the idea. 

High fawn survival rates are great, but they also lead to the need for high deer harvest rates. This is why healthy deer herds maintain a low buck to doe ratio. Time for another example: Let’s say a ranch can support 100 healthy deer and the buck to doe ratio is 1:5, or 20 bucks and 80 does. A modest 50% fawn crop means that 20 buck fawns and 20 doe fawns will be produced. To maintain the population at a healthy density this means 20 bucks and 20 does must be removed during the hunting season—but there are only 20 adult bucks! If the buck to doe ratio was brought down to 1:1 then a modest 50% fawn crop would mean that 50 does would have 25 fawns, or approximately 12 buck and 12 doe fawns. The addition of these animals into the population would warrant shooting 12 bucks and 12 does. Luckily, there are 50 adult bucks and adult does to choose from. The hunters could harvest 12 bucks and still have a good age structure in the buck population.

Hopefully, understanding the dynamics of a deer population will help you identify each of these factors on your property and help you reach your white-tailed deer management objectives.The annual harvest rate of white-tailed deer on any property is determined by deer density, habitat condition, the buck to doe ratio, and fawn survival. Factors that impact the body condition of individual deer will impact the dynamics of the population as a whole. Good habitat will lead to higher fawn production and the need for a higher deer harvest rate, but managers can mitigate excessive production by manipulating the buck to doe ratio.

When it comes to white-tailed deer management—at any scale—the most important factors are deer density and buck to doe ratio. These  two numbers are usually indicative of habitat condition and the reproductive potential of the deer herd. Most hunters continue to talk about buck harvest criteria, and although important, they fail to have a good handle on the deer density and buck to doe ratio in their hunting area! In addition, many landowners overlook habitat conditions and factors that limit fawn production and survival.

White-tailed deer harvest rates are important because they determine not only the number of animals you will shoot this year, but more importantly the number of deer that will survive into next year. This is especially important for the doe population because these animals, depending on deer density and sex ratio, can increase the total deer population prior to the next hunting season by 50% or more. This article discusses population and environmental factors that influence white-tailed deer harvest rates on an annual basis. 

Harvest rates can vary annually by habitat quantity, habitat quality, fawn production, and white-tailed deer management objectives. Hunters and landowners looking to maintain healthy age structure in bucks should never harvest over 20% of the buck herd. This holds true whether the buck to doe ratio is 1:10 or 1:1. Of course, if the deer density in the area is held constant, many more bucks can be harvested when there is 1 buck for every 1 doe compared to when there is 1 buck for every 10 does. Many hunters fail to realize that from a population standpoint the types of the bucks being shot is less important as the total number of bucks being removed from the herd. In short, limit buck harvest to less than 20% of the buck population. 

Doe harvest management is more important in determining the overall dynamics of a white-tailed deer population in a given area. The doe population determines if a deer population declines, remains stable, or grows. However, the doe population is dependent on, as mentioned prior, habitat quantity, habitat quality, fawn production, and management objectives. Because the doe population in an area depends on these annual factors, so does the annual harvest rates. 

Habitat Quantity

This is a measure of the total amount of deer habitat available. Does your property have 100 acres of deer habitat or 1,000 acres of deer habitat? Obviously, more deer habitat correlates with a larger population size. Hunters on 100 acres of habitat can not expect to harvest as many deer as hunters on 1,000 acres of habitat, assuming the deer density in that habitat is the same. If both ranches have the same harvest strategy in place, then the 1,000 acres of habitat can harvest 10 times the number of animals. It’s not because those hunters are greedy, it is just that the total deer harvest for a property should be related to available deer habitat, not just property size. In this example, both ranches could have been 1,000 acres in size. We only discussed available deer habitat on those properties. Property size will not effect the harvest rate, only the total number of animals harvested (because of available habitat).

Habitat Quality

Habitat quality is measured by an area’s ability to provide food, cover, water, and space for white-tailed deer. Deer found on high quality habitat have higher reproductive rates than deer found on low quality habitat. Here is an example of how habitat quality impacts harvest rate: Let’s say that there are two ranches 1,000 acres in size. One provides high quality habitat and the other provides low quality habitat. If we assume that the deer density is the same, then fawn production on the high quality habitat will be higher because there is more food per animal. This high quality habitat means more food per doe, a higher reproductive rate, a higher fawn survival rate, and more bucks and does available for harvest each year. In short, properties with high quality habitat must harvest does at a higher rate to keep the deer population stable.    

In Summary

Without a doubt, both habitat quantity and quality impact the annual harvest rates of a deer population. Property size does not impact harvest rate, but smaller properties will harvest fewer animals than larger properties based simply on habitat quantity and differences in the sizes of the deer populations. Habitat quality can vary by property depending on habitat management practices (or lack thereof) and deer found on high quality habitat have higher reproductive success. Because of this habitat effect, properties providing high quality habitat must harvest does at higher rates than properties providing low quality deer habitat. Next week, I will discuss how fawn survival, density, and buck to doe ratio also impact white-tailed deer harvest rates.

Not all that many years ago it was considered unsportsman-like to shoot a doe deer. Since then, however, wildlife biologists and hunters have realized that proper doe harvest is an important part of white-tailed deer management, although I suspect there is a small percentage of landowners that still do not allow doe to be harvested on their properties. After all, a landowner has the ability to be more conservative than the law and choose not to harvest antlerless deer, even if hunting regulations permit it.

But is a no doe harvest really justified? Maybe, but then maybe not—particarly if the only reason holding someone back is the “old school” philosophy of not shooting female deer. It is true that the shooting of does may not be justified in some areas. Not every deer whitetail population can sustain regular doe harvest. Some deer herds may allow periodic doe harvest, such as every other year or every third year, for example, while others need regular (annual) doe harvest to thrive. So why does the harvest of whitetail doe vary by area?   

To answer this question, let’s first take a look at why hunters harvest deer. Sportsmen across the country take to the field each fall in pursuit of trophy bucks, and venison makes great table fare, but the primary reason we can hunt is because it’s necessary. White-tailed deer are an important resource. In fact, they are a renewable natural resource. The only reason we have a deer season at all is because white-tailed deer are a keystone species in the habitats that they occupy. State governments and wildlife departments use hunters to maintain deer populations at healthy levels, otherwise the habitats that they occupy, which are important to other wildlife species, will suffer.

In short, hunters themselves are an important component of deer management at the state, county, and management unit level. In the U.S., most states use counties or units marked by roadways to designate areas of management. In Texas, white-tailed deer hunting regulations are setup by county. Since the habitat and deer population often vary by county, so do the deer hunting regulations. This makes sense because habitat quality and the resulting deer population are not the same in every area. As a result, the buck, doe, and total deer harvest rates can not be the same for every area.

On private property, hunters must use property lines to identify their management unit, unless neighboring landowners form deer management associations (co-ops) and work together to achieve the same objectives. The most important component of deer management is maintaining a healthy balance between the local deer population and the available habitat. Because deer populations vary by habitat type, you can now see that doe harvest may be warranted in some areas, but not in others. Next week I will write about specific factors that influence deer populations and how those factors impact both buck and doe harvest rates.

Every hunter wants to harvest a trophy buck, but when it comes to white-tailed deer hunting the reality falls somewhere between shooting a big buck versus deer overpopulation. On one hand, you have hunters that really just want to harvest a single deer, preferably a big, mature buck. Then on the other hand, you have deer numbers that need to be controlled. This will probably not come as a surprise to you, but the average deer hunter only wants to harvest one deer, or more precisely, one buck. While most hunters love seeing numerous deer while out in the field, an important part of deer management is population management.    

The reason I bring this up is because just this last week ranches near Kerrville, on the western edge of the Texas Hill Country, were finding dead deer after several days of cold and wet weather. The cause of these deaths — malnutrition. And before assuming that these deer were confined within a high fence that maintained too many animals, I’ll let you know that they were not. In fact, most of the animals found dead were free-ranging white-tailed and axis deer, but they were all starving. Basically, the deer population of the area has exceeded the carrying capacity of the winter range. They were all competing for limited winter forage, and the weakest died.      

Reports indicate that the found deer were in poor physical condition, hip bones exposed, backbones showing, and no internal fat. The rumens of most of the dead whitetails were packed with cedar, some dead oak leaves, and even yucca leaves. Axis deer rumens were packed primarily with dry grasses. The cedars (ashe juniper) in the vicinity of the dead animals were severely browsed. Obviously, the cause of death was malnutrition caused by overpopulation that was exacerbated by the cold, wet conditions that persisted over several days.

Axis deer are more susceptible to cold, wet weather than white-tailed deer because they are an exotic subtropical species, but the end result of malnutrition is realized when mixed with winter weather. Deer in less than optimal condition are always more susceptible to disease and death. Additionally, parasite loads can only make an individual animal’s situation worse. So how can winter die-offs be avoided?

First, the deer population must be kept in check with the habitat. Sure, you may only want to harvest one buck, but realize that the health of each individual deer depends on the availability of food. Supplemental feeding can help, but only if it’s at an adequate level and of the proper type to support the deer population. Each deer impacts every other deer because of the competition for limited resources, but this contest can be greatly reduced if free-choice supplemental food is provided 24-7, year-round. When animals are found dead, remember that the weakest die first. 

When monitoring a deer population, many factors can indicate potential deer management problems. Individual body weights, fawn survival (as an indicator of doe and habitat health), and habitat use can all be used to gauge herd health. With that said, pay close attention to the health of deer harvested early in the season. Underweight deer (for their age) are good indicators of a potential problem. In addition, if deer are eating undesirable species, such as cedar, they and the habitat are in very poor condition.

Last week I wrote an article discussing harvesting white-tailed deer early in the season, which I strongly recommend. The article discussed why it is important to remove deer before winter, especially does, and the benefits of having a deer herd at carrying capacity. Well, one reader posed a question that many of you may be interested in:

“What about nursing fawns early in the season? Will taking lactating does hinder growth and development in these young deer?”

Yes and no. To begin, whitetail fawns are usually weaned and become functioning ruminants at eight weeks of age. Most fawns at southern latitudes are born in late May and June, meaning the majority of fawns are weaned by the end of August. And this makes sense from a biological perspective, because as late-summer food sources deplete the doe can then rely on the fawn to nourish itself. This covers the majority of whitetail fawns that hunters will encounter in the field during the fall hunting season.

However, if you see a late-born fawn that still has spots, then I would not recommend harvesting the doe. Spots suggests that the deer is not old enough to survive on natural forage alone. With that said, fawn survival ultimately depends on habitat quality. Malnutrition and associated problems are the primary cause of poor fawn survival in most areas. Poor habitat does not help the doe feed the fawn, or the fawn feed itself after it is weaned. Poor habitat is bad for recruitment and drought conditions only aggravate the problem of inadequate food.

In general, harvesting does with fawns will not impact an individual fawn, unless of course the fawn is less than two months in age. Fawns older than two months, found in areas with good habitat, are just as likely to survive after the doe is removed. In short, if you need to remove does to get your deer herd at carrying capacity, do not hesitate to harvest does with older fawns.