August 25, 2022 at 11:51 a.m.
'Deer czar' Kroll speaks to Natural Resources Board
Touts importance of DMAP, CDACs, requests browse surveys
'Deer czar' Kroll speaks to Natural Resources Board
The plan gave recommendations in eight categories. Those were population management, hunting regulations, seasons and bag limits, predator issues and management, CWD, harvest monitoring, habitat, people and DNR research and technical publications. In his presentation to the NRB, Kroll focused on population management, predator issues, harvest monitoring, habitat and people. He focused on two programs he said have been successful in the state, the Deer Managment Assistance Program (DMAP) and the County Deer Advisory Councils (CDACs).
Kroll touted both program as successful, but said there needs to be a nexus between the two of them. An overarching theme of his presentation was that deer populations cannot be "managed," per se, but tweaks could be made to move the needle in the desired direction. He also said all deer management techniques must be site specific.
DMAP
"You don't manage deer in Lansing," he said. "You don't manage deer in Madison." Each site or piece of property should be managed differently, based on its unique habitat as well as other factors. DMAP, he said, was a shinning example of how deer could be managed at a site level. This program, he said, involved all three "legs of the management stool," as he called them. Those "legs" are habitat, people and populations. Involving the general public in deer management through a program such as DMAP makes it more tangible and creates buy-in from the public, he said. There are currently 1,905 participants in the program statewide, accounting for over 407.200 acres of land.
"Involving landowners, hunters and other stakeholders in the data collection and analysis process creates trust between the public, professionals and the game agency," he said. Kroll stated he and other researchers had found this to be a successful formula from Mexico to Canada in the last decades.
The essence of DMAP, he said, is that biologists do not manage deer. People do. The role of the biologist is to assess goals of the people in the program, then provide assistance in reaching those goals. Biologists also provide critical data to inform decision making and aid in evaluation of the progress toward the goals. He did call for more cooperative research, possibly with the University of Wisconsin system, which he felt would help with conducting research for critical needs data.
An area where Kroll said DMAP could be more effective is in the way of comparing the DMAP property to the DMU. One cooperator, he said, should be able to look at the data from their land and compare that to the DMU average. From there they could ask their biologist for guidance on why their data may be different and what they can do to change it.
CDAC
Kroll called the County Deer Advisory Councils (CDACs) the "next step up" from the DMAP program. These councils were formed in September of 2014 in all counties to gather input from citizens and make recommendations to the Department of Natural Resources (DNR) on deer issues in their respective counties.
The CDACs are charged with reviewing and considering scientific metrics on deer herds, impacts to habitat and agriculture and human-deer interactions. These recommendations include deer population objectives, antlerless quotas and herd management strategies.
Management strategies, Kroll said, would be evaluated on a yearly basis to determine whether those strategies are moving the bar toward the objective. This involved two types of data, he said: baseline data and continuous record-keeping. The continuous record-keeping, he said, should be used to serve as an "early warning" system of sorts to point to potential emerging problems. Checking to ensure management techniques are providing the desired outcome is important.
"What is the most effective management tool?" Kroll asked. "The one that is used." Tools must be used and evaluated on a regular basis to test their efficacy.
Again, Kroll spoke about browse surveys and how those would prove beneficial to CDACs as well. It would be one more metric with which to inform council members and to help them in their decision-making process.
Populations
Kroll called an "accurate population number" the LeBrea Tar Pits of Wildlife Management. His report called for limiting the historically-used sex-age-kill (SAK) model that looked to determine specific population numbers. Wildlife managers took that advice and have since let SAK fall by the wayside.
"You're not going to do it," Kroll said of developing an exact population number, not only for deer, but for any wildlife species. "It is not really possible, and it has gotten more wildlife agencies into hot water." His report called for the metric used by CDACs today - to increase, decrease or maintain the deer herd at the current level." His report also called for the development of a set of metrics to monitor progress toward the Deer Management Unit (DMU) goal. He noted that some of those metrics had yet to be developed in the state. He said there are clues as to what is happening with any deer herd in any location.
"If you ask the right questions, the deer are more than happy to tell you how they're doing," he said. "And if you ask the right questions, the habitat is more than happy to tell you how it's doing. You just have to ask the right questions, and get the answers." Again he stressed that humans do not manage the deer ecosystem. They simply fine tune it.
The questions to be asked, Kroll said, include herd stocking levels, demographics, recruitment, herd health and mortality factors and age-related antler quality. These factors will help managers understand more about the herd in question.
Stocking level is one of the most important population questions to be answered. It is independent of density and should be expressed as low, moderate or complete. Two adjacent properties can have different stocking levels, based on available habitat, he noted. Two properties can have the same number of deer, but different stocking levels, or different numbers of deer, but the same stocking level. CDACs in the Northwoods have referred to stocking level as "carrying capacity," or the number of deer that can be supported, based on available habitat.
Goals for a site, Kroll said, should be based on both harvest and habitat of that area. He said there is no need to estimate a population size, other than to look at trends.
Lack of browse surveys
One area Kroll saw as lacking with deer management in the state had to do with stocking levels or carrying capacity. He said that while deer eat a variety of food, they do have distinct preferences based on palatability and digestibility. Browse preference is classified by first, second, third and emergency preference. Browse surveys, he said, were not readily available in many states, including Wisconsin, but have been used successfully in the south for many years. Browse survey data was created in Texas by a colleague of Kroll's in the 1960s and has been used in deer management since then in many places. The data gives managers an idea of stocking capacity based on the percentage of browse in each preference category and has been developed over time to allow for management based on available browse species and at what level each are browsed.
Kroll revisited the state's lack of browse surveys several times. Several members of the NRB, too, had called for the completion of browse surveys in recent years. While forest managers have stated, in some areas, there was "too much" browse and deer herds needed to be reduced, there has been no firm data in the way of browse surveys to determine if this is true. The biggest concern, he said, seemed to be on forestry and forest regeneration.
"There needs to be a shift in mentality away from the impact of deer on the forest to include the impacts of the forest on the deer herd," he said.
Fawn crop versus recruitment
The fawn crop, and ratio of adult female deer to fawns, is used in Wisconsin to help determine which direction deer populations are headed. A more important number, though, according to Kroll, is the recruitment number. The recruitment number is the number or percentage of fawns born last year that are alive in the current year as yearlings. Not all fawns that live through their first summer make it to the following year, he said. There is over-winter mortality in all ages of deer. The numbers presented in Wisconsin are post-hunt numbers, he said, but there is more to the picture.
"What goes no between post-hunt and the next fall?" Kroll asked. Conditions such as the Kidey Fat Index (KFI) and the Bone Marrow Fat (BMF) as well as parasites and disease abundance can all have some bearing on recruitment of fawns.
Kroll said there are other indicators of herd health as well that can be used as metrics. Those include body weight and age related antler quality.
"What should a mature buck weigh in Bayfield County?" he asked, as an example. "What should it weigh? That gives us a benchmark to compare against what they're actually weighing." This background data is important in that regard.
Health checks
Kroll also spoke about health checks and involving the public in those checks. He said he and his team have necropsied thousands of deer over the years. On average, 50-60 members of the public, whether hunters, land managers or other stakeholders, have attended these health checks, asking questions and learning more about how herd health can be determined.
Completing these health checks, he said, not only gives managers great data, but also builds credibility with the public. Conducting these health checks in southern Michigan, and inviting the public, has worked to change opinions and attitudes about deer management, he said. He called for Wisconsin to begin the same type of program, conducting necropsy health checks and inviting the public to come and view these checks. He called it "the best thing an agency can do, working in coordination with the public."
Currently, in Wisconsin, deer health is reported only in terms of winter severity index, Chronic wasting disease (CWD) and Epizootic Hemorrhagic Disease (EHD). However, there is much more to deer health, Kroll said. These health checks look at many more factors of deer health. He called for requiring deer biologists to conduct these checks in different regions of the state, allowing the public to attend and learn more about the process.
Habitat
Kroll said habitat fragmentation is one of the biggest issues facing the deer herd. It has been in a "downward spiral," he said, for decades. In order to better understand how this is evolving and increasing, he called for the use of geospatial surveys. These surveys would prove useful for managers to fully understand changes in land cover over the years.
Kroll called for splitting these surveys into public and private land as well. The differences in land cover vary from one type of property to the other and understanding those differences would prove important in proper guiding of the deer herd population numbers.
Predators
No conversation about deer herd health can be complete without looking at the role of predators, and Kroll spoke to this as well. Kroll said the state needed to do more research in this area. A suite of predators has developed over the last 20 years in the state and their effects on the deer herd have not been fully studied, he said. For proper management, the cumulative effects of these suites of predators need to be known and understood, he said. He called for more research in this area, adding it should be objective research. He said the state needed well planned, targeted research on this area of deer management.
Beckie Gaskill may be reached via email at [email protected].
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