whitetail | Buck Manager

The Spread of CWD in White-tailed Deer

Serious diseases such as chronic wasting disease (CWD) can be detrimental to whitetail deer management programs with mortalities impacting local deer numbers as well as regional and potentially even statewide deer populations. State agencies around the country have been monitoring CWD in deer herds for many years now, and they know that it is caused by prions, but much about the spread of the disease was unknown until now. Researchers have discovered that deer asymptomatic for the fatal brain condition known as CWD excrete the infectious prions that cause the disease in their feces.

The finding suggests a reasonable explanation for transmission of the disease among white-tailed deer, mule deer, and possibly elk and moose in the environment. While the study reveals that prions are shed in feces of symptomatic deer as well, the discovery that the infected deer shed prions in their feces many months before they show clinical symptoms is the most unsettling. White-tailed deer, mule deer, elk and moose inadvertently consume feces and soil in the course of their daily browsing and grazing.

The prion is an infectious form of the normal prion protein, which has been found in all mammals examined, including humans. The lethal, infectious form induces the normal protein to twist into a malconformation, initiating a disease process that ravages the brain. Prion diseases, seen in cervids, sheep, cows and humans, are also referred to as spongiform encephalopathies. In wid and captive deer, researchers now know that the inadvertant consumption of feces is how the disease is transferred from animal to animal. So what’s the next step?

With this information in hand, the researchers set out to determine whether the animals could develop chronic wasting disease through long-term consumption of contaminated feces. They did so by measuring the amount of prions contained in the feces of orally infected deer up until the time they became symptomatic and then calculated whether prolonged exposure to the concentrations of prions in these feces would be enough to cause the disease.

“Prion levels in feces samples of asymptomatic deer were very low compared to those in the brains of the same deer at the time of death,” says the lead author of the study, Erdem Tamguney, PhD, an assistant professor at the Institute for Neurodegenerative Diseases, based at UCSF. “However, the total number of prions excreted over time was sufficiently high enough to cause disease in other deer.”

The susceptibility of animals to infection, he says, may also be increased by the simultaneous ingestion of clay soil, which is thought to enhance the infectivity of prions, possibly by slowing their clearance from the gastrointestinal tract.

“Our findings suggest that prolonged fecal prion excretion by infected deer provides a plausible explanation for the high level of transmission of chronic wasting disease within deer herds, as well as prion transmission among deer and other cervid species. Our work may also explain transmission of scrapie prions among sheep and goats,” says senior author and Nobel laureate Stanley B. Prusiner, MD, UCSF professor of neurology and director of the UCSF Institute for Neurodegenerative Diseases.

The study did not examine whether CWD could be transmitted to humans via exposure to deer feces. To date, transgenic mouse studies have indicated that chronic wasting disease does not transmit to humans, but scientists remain open to the possibility that it could.

“We can only say that prions of chronic wasting disease have not transmitted to mice genetically engineered to carry the normal, healthy form of human prion protein in earlier studies,” says Prusiner. “That said, we do not know for sure that deer or elk prions cannot be transmitted to humans.”

Are White-tailed Deer Getting Smaller?

Small Deer in Your Area?

Have years of heavy hunting pressure impacted deer body condition and antler quality in your area? It may be difficult to say with any certainty, but it seems plausible that deer hunters, which serve as predators, could alter the gene pool of certain game species. Last month, an article presented research that found hunting had a profound impact on wildlife, driving an evolutionary process that makes animals become smaller and reproduce earlier.

The study, which looked at both hunting and fishing, examined 29 different species and found, that under human pressure, creatures on average become 20% smaller. Do deer use more energy trying to evade predators, hunters?

Feeling the Pressure

Article: “The human tendency to seek large ‘trophies’ appears to drive evolution much faster than hunting by other predators, which pick off the small and the weak.

Researchers reported, ‘It’s an ideal recipe for rapid trait change.’ In virtually all cases, human-targeted species got smaller and smaller and started reproducing at younger ages — making populations more vulnerable.

Hunters are instructed not to take smaller animals or those with smaller horns. This is counter to patterns of natural predation, and now we’re seeing the consequences of this management.”

Small Deer Study in Focus

This study makes some very good points with regards to hunters in general being trophy-oriented, but hunters and landowners partaking in intensive deer management programs are doing exactly the opposite. I have often believed that under certain conditions, such as extreme hunting pressure, particularly with regards to the overharvest of young bucks, that gene pools could be negatively impacted.

For example, some properties consider themselves “managed” by having an 8 point or better rule on harvested bucks. However, regular readers of this site know that the best yearling (1 1/2 years old) bucks can have 8+ points. This can result in decades of hunters high-grading their buck herd.

So by looking at common hunting practices this way, it becomes quite apparent that humans, particularly hunters, can impact gene pools. This is especially true in wildlife species that, like deer, are relatively short-lived. Common sense would conclude that just several years (which for deer would be several generations) of extreme pressure could alter whitetail genes in a given area. And if you are a management-minded hunter, that is exactly what you want.

Just as improper harvest can impact a deer herd negatively, proper deer harvest centered around a well-thought-out deer management program can continually change the gene pool for the better. In fact, this is exactly what the culling of inferior bucks is intended to do. Bigger-bodied whitetail bucks, much more often than not, grow larger antlers than their smaller-bodied counterparts. These bigger deer are also able to cope better with harsh winters, summer droughts, and better fight off would-be predators. In summary, help mother nature do her job and improve your white-tailed deer herd by harvesting those deer that are small for their age class.

Deer Not Eating Protein Pellets?

Genetics (genes) are the most important factor in determining antler characteristics in whitetail bucks. However, genes are not the only factors that determines a buck’s antler potential. Both age and nutritioninfluence how a deer’s genes are expressed. For example, even a buck with the genetic composition to grow the largest rack in the world was harvested at a young age or was malnourished, then the genes that the buck carried were never fully observed. Because age and nutrition determine how a buck’s genes are expressed, these factors are critical to the success of a sound deer management program that strives to produce high-quality bucks.

Although proper buck harvest is necessary to promote age and antler characteristics, nutrition can be achieved through a combination of habitat management and supplemental feeding. Habitat management is the single best way to provide year-round, high-quality food for deer, but this is typically only a viable option for land owners. Habitat management is not always feasible for hunters that lease land for deer hunting for a variety of reasons. In this case, hunters are limited to providing supplemental food through either food plots or free-choice protein pellets. Continue reading “Deer Not Eating Protein Pellets?”

Buck Management: What’s Up with Missing Brow Tines?

The hunting season has just ended for the majority of white-tailed deer hunters. Now, it’s time to reflect, look back over the past season while it’s all fresh in your mind. If you had the opportunity to spend many days in the field hunting, then you should have a good picture of the overall deer herd using the property you hunt.

Better yet, if you recorded deer observations while hunting, then you have the hard data to support what is happening under your property’s current deer management program. These field observations, in addition to game camera photos, will allow a deer manager to track individual bucks from one year to the next. I strongly recommend keeping both photo and stand observations since some bucks always seem to avoid getting caught on camera.

Are missing brow tines caused by genetics?

Missing Brow Tines

With regards to antlered deer, one issue that always seems to arise is the lack of brow tines (G1) on some whitetail bucks. Hunters have often questioned why some middle-aged and mature bucks simply lack brow tines. Is something going on in the deer herd?

Well, yes. Antler characteristics are genetically linked and highly heritable This means a young buck will likely look a whole lot like his daddy. To back up this claim, I will cite some long-term data collected from Kerr Wildlife Management Area (WMA), located in Texas.

From 1974 to 1997, the research facility at the Kerr WMA was involved in a number of studies designed to determine the role of nutrition and genetics in white-tailed deer antler development. During each of various studies that took place over that time, researchers recorded antler information for individual whitetail bucks throughout a 23 year period.

Deer Hunting and Management

Brow Tines on a Buck?

This wealth of antler data allowed wildlife biologists to back-test 217 whitetail bucks from yearlings (1 1/2) to 3 1/2 years of age and 168 bucks until they were 4 1/2 years old. That’s a lot of deer, and from what I can find, represents one of the largest sets of antler data available. So what did they find?

In short, data from 385 bucks found that 90 percent of the bucks without brow tines at 3 1/2 and 4 1/2 years of age were spikes at 1 1/2 years old! All bucks without brow tines at 1 1/2 years old lacked brow tines at 4 1/2 years old. On the other hand, all bucks with 5 or more points as yearlings had both brow tines at maturity. Bucks that had both brow tines as yearlings had both brow tines at 3 1/2 and 4 1/2 years of age.

Missing Brow Tines Starts with Spike Bucks

Incredible Antler Data

The numbers above speak for themselves. In addition, deer researchers know that antler characteristics in white-tailed deer are highly heritable, so the probability of passing on genes for specific antler characteristics (larger or smaller antlers) is a given. The future of the deer herd on a property depends a good amount on the quality of the bucks doing the breeding.

To sum up, a whitetail buck that has spikes as his first set of antlers has a 90 percent chance of developing into a buck with missing brow tines later in life. A buck that has 5 or more points as his first set of antlers is much more likely to have brow tines later in life, at least according to this data set out of Texas.

Deer Management Implications

How does knowing this information affect you and the deer you manage moving forward? It likely depends on the goals you have for the deer that use your property. If one of the goals is to harvest the maximum number of mature bucks on the property annually then you want to allow all bucks to reach maturity.

However, if you are looking to improve buck antler quality, then at least one of the factors you should consider is the quality of the young bucks on your land. Antlers are the result of genetics, but they are also influenced by the environment. Nutrition plays a role in how genes are expressed, how a buck looks.

This phenomenon can be seen is deer herds with suboptimal nutrition as spike bucks tend to comprise a higher percentage of the young bucks, those 1 1/2 years of age with their very first set of hardened antlers. In these types of situations, increasing the available food by reducing the size of the total deer herd or the addition of supplemental foods/forages may be an appropriate step to increase overall deer health, buck quality.

If a property provides ample food and a manager is seeing a high percentage of 1 1/2 year old bucks without brow tines on the property, then you now know it’s all in the genes. The only way to improve antler quality and reverse missing brow tines in older bucks is to put pressure on spikes and bucks without brow tines, regardless of age.

Deer Management for Brow Tines, Better Antlers

In this situation, deer management practices should also include rolling over the doe herd to reduce the number of old does sired by bucks lacking brow tines. This is not a management strategy that plays out overnight, but a practice that must be integrated into the long-term management of a deer herd using a property.

When Whitetail Bucks Lock Antlers

Each fall, as testosterone levels rise in white-tailed bucks they begin working off aggression by working rubs and building up much needed shoulder and neck muscles. It’s not an accident and if you’ve ever noticed the changes that a buck’s body undergoes between late August and late October, it really is amazing. However, as the breeding season — known as the rut by hunters — begins, whitetail bucks that were friendly towards one another during the antler growing period quickly become rivals. It’s all about a battle for space and access to receptive does.

The rut really takes its toll on bucks. Not only do bucks lose a substantial percentage of their body weight over the course of the breeding season, but buck to buck combat can lead to both direct and indirect mortality. Indirect mortality can come from wounds that become infected or even internal damage from fighting. Direct mortality, although more infrequent, can occur when two or three bucks’ antlers become locked together causing one or both animals to die.

This is the case today for one deer. I received these photos of two locked up white-tailed bucks from Minnesota. The guys that stumbled upon the bucks actually found them while one of the bucks was still alive. Instead of shooting the locked up buck, they managed to separate the two and send one lucky deer on his way. Here is the story: Continue reading “When Whitetail Bucks Lock Antlers”