Image Image Image Image Image

Buck Fever Raffle

Support the D.E.E.R. Project and purchase a raffle ticket for a chance to win a 2019 Wyoming Commissioner’s License. * Read below for information on the project.

Dr. Kevin Monteith update:

The end of 2018 marked 3 years of data collection for the DEER Project. From those 3 years of data collection, we’ve gained invaluable data that will aide in our understanding of the intricate dynamics between deer, elk, their predators and their environment in southwest Wyoming. Although preliminary, we’ve learned mule deer and elk are using many of the same resources, but use different areas on the landscape, and that survival of adult elk is much higher than that of deer. We know from 3 seasons of summer field work that survival of young elk is high, but survival of young mule deer contrastingly low, and practically insufficient for sustaining a population of mule deer. The causes of such low survival for young deer, however, has shifted across the years, and indicates there are likely multiple, interactive factors at play.

Over the past 3 years, the DEER Project has strived to take a comprehensive approach to evaluating factors that influence population dynamics of mule deer and elk, but through recent partnerships with several conservation organizations we simultaneously have the opportunity to expand our understanding of predator-prey dynamics in the region. As expected, predation on neonates has occurred across all years of the DEER Project but has had the potential to significantly impact survival of fawns and adults in some instances. Nevertheless, we have a unique opportunity to understand in great detail predator movement and space use, and how it relates to survival of neonatal ungulates.

We have recently succeeded in garnering a sufficient sample of GPS collared individuals from two of the most prolific predators of mule deer: coyotes and mountain lions. These data, along with survival of neonates, behavior and nutritional condition of female deer, provides rarely observed links with vulnerability to mortality associated with predation. For instance, understanding whether coyotes actively seek neonatal mule deer during parturition provides context as to one of the mechanisms behind potential effects coyotes may have on fawn survival—all of this information, however, would not be possible without the use of GPS data. Hence, the lessons we can learn from a more in-depth evaluation of predator movement and space use alongside monitoring closely the behavior and performance of their ungulate prey will be a worthwhile investment and provide immense return to our understanding of factors shaping population dynamics of mule deer.

We have been fortunate to work closely with Wyoming Game and Fish Department to deploy GPS collars on 28 coyotes and 5 mountain lions throughout the Greater Little Mountain Ecosystem. The GPS data collected from two key predators along with the plethora of data we have already collected from the DEER Project provides an unprecedented opportunity to explore relationships between predators, prey, and their environment. Accordingly, we are striving to employ an additional season of field work in the summer of 2019 for the DEER Project where we hope to be capturing and collaring neonatal mule deer, monitoring and assessing vegetation on the landscape, and evaluating cause-specific mortality of adults and neonates.

As we begin pivoting more toward analysis of data we are focusing on the larger question we set out to answer: Are mule deer and elk in competition on the landscape? Determining if mule deer and elk compete, and if they do, the extent to which they compete, will put us in a better position to understand what the coexistence of these two valued species means for decisions associated with population and habitat management. And for that matter, their future persistence in this high-desert system. For the first time ever, we have data on individuals of both mule deer and elk, including: diet, space use, habitat use, individual nutritional condition, neonate survival, cause of mortality and more. We will continue to fill in gaps within our data through the next year and continue to work with our wealth of collaborators and partners to bring data to questions that have loomed for decades.


Movement


Diet


Survival

The reason for low mule deer survival has varied depending on the year. Predation rates on adult female mule deer has been relatively high over the past three years—attributed primarily to mountain lions. Nevertheless, in 2017 and 2018 we have observed 12 cases of potential disease in adult female mule deer.

Predation on neonates is common and typically higher than mortality of adults. Causes of predation are primarily from two predators, mountain lions and coyotes.


Nutrition Conditions

Comparing to the Wyoming Range Mule Deer Herd

Although much remains to be understood, different patterns appear to be at play in the Wyoming Range Herd versus the animals residing south of Rock Springs. It would appear that over the harsh 2016-2017 winter, the Wyoming Range deer lost proportionally more fat than deer in the South Rock Springs herd. Interestingly, females in the Wyoming Range gained about 3 times the fat reserves that females in South Rock Springs herd gained the following summer. These patterns may indicate that summer range conditions in the Wyoming Range are far better than those south of Rock Springs, and conversely, that winter range conditions in the Wyoming Range are less favorable for deer compared to south of Rock Springs. More investigation will help us understand the patterns and processes affecting differential fat gain between these two herds and how that operates to affect population dynamics. A consistent picture has emerged that individuals in the Greater Little Mountain Ecosystem are in generally poorer condition compared with animals elsewhere in the state that we have been monitoring. In addition, mule deer in the greater Little Mountain Ecosystem are up to 30% smaller than deer that reside nearby just north of Interstate 80—likely an indicator of long-term patterns of nutrition.


Coyotes


Coyotes have been implicated as a primary detriment to survival of neonates in many systems across North America, however, much less is known as to how space use and demography of coyotes influence survival of neonates. The overarching question of the coyote-centric segment of our research is aimed at asking how the demography and behavior of coyotes affects their ability to regulate the abundance and fitness of sympatric large ungulates with differing life-history strategies (mule deer and elk), especially focused on neonate survival and recruitment. We intend for this work to examine neonate survival by understanding how mule deer and elk, both of which differ in body size and vulnerability to predation, respond to the presence and risk of predation from coyotes, and the effects of coyote predation on mule deer and elk population dynamics. To address these questions, we wanted to know what factors influence coyote predation events, and how the risk of coyote predation influences the behavior of female mule deer and elk during parturition.

To examine the effects that coyotes are having on neonate survival in the GLMA, as well as to better understand coyote demography and behavior, we currently have 26 coyotes collared in the study area—13 males and 13 females. We have been able to achieve a fairly good spread of individuals throughout the entire area. Generally speaking, the coyotes we have captured have been young (1–4 years old) with the exception of a few individuals that have been upwards of 6 years old. For instance, we captured a 6-year-old female in April of 2017 that was pregnant with 2 pups at the time. On average, these coyotes have weighed around 25 pounds, although we have captured 2 male coyotes that weighed just over 40 pounds!


Coyotes and Mule Deer


In many systems, coyotes are a primary predator of neonates, and have the potential to have detrimental effects on their survival. What’s less clear, however, is whether coyotes actively seek areas used by female deer during parturition or come across neonates opportunistically. Thus, we evaluated how coyotes behave during parturition of mule deer, and whether they actually seek areas more likely to be used by mule deer and potentially take advantage of a plentiful, and profitable prey resource.


Before parturition of mule deer, coyotes were much 50 times more likely to use an area used by a deer than an area that was not. During the window when most deer were giving birth when a pulse of vulnerable fawns become available on the landscape, coyotes were 240 times more likely to use an area used by a deer than an area that was not used by a deer. After parturition, however, coyotes avoided areas that were used by deer, completely changing their behavior relative to where deer are using the landscape (Figure 7). So, why do coyotes avoid areas used by deer after parturition? Although we don’t know for certain, we suspect coyotes are changing their behavior after parturition because there may be another pulse of vulnerable prey that are available to coyotes such as rabbits or other small mammals.

Figure 10. Selection by coyotes relative to areas used by female deer. Coyotes strongly selected for areas used by deer before parturition, but increased their selection by 240 times during parturition. After parturition, however, coyotes strongly avoided areas used by deer after parturition.


Where female deer are at on the landscape seems to be a really important factor shaping where coyotes spend their time. For instance, during parturition of deer, coyotes avoided areas of higher sagebrush height and selected areas that were farther from roads, however, the importance of sagebrush height was 5 times less important than deer, and distance to roads was 50 times less important than where female deer were present on the landscape (Figure 9).

Figure 11. Relative importance of sagebrush height and distance to roads on selection by coyotes compared to deer during parturition. Overall, sagebrush height and distance to roads are orders of magnitude less important than deer in determining areas where coyotes occur on the landscape.


All of this this information, regarding coyote behavior during parturition, although it does not provide information as to how many fawns are killed by coyotes, it allows for much greater resolution into the potential consequences of coyote behavior during parturition of deer. Indeed, such search behavior exhibited by coyotes supports the notion that this cunning predator is capitalizing on a pulse of food resources that appears on the landscape each spring and helps explain why they often are one of the leading proximal causes of mortality for young mule deer. Further work will seek to understand how coyote behavior, habitat occupied by each neonate as well as their condition interact to affect whether or not a young mule deer survives or succumbs to mortality.


GOING FORWARD


The end of 2018 marked 3 years of data collection for the DEER Project. From those 3 years of data collection, we’ve gained invaluable data that will aide in our understanding of the intricate dynamics between deer, elk, their predators and their environment in southwest Wyoming. Although preliminary, we’ve learned mule deer and elk are using many of the same resources, but use different areas on the landscape, and that survival of adult elk is much higher than that of deer. We know from 3 seasons of summer field work that survival of young elk is high, but survival of young mule deer contrastingly low, and practically insufficient for sustaining a population of mule deer. The causes of such low survival for young deer, however, has shifted across the years, and indicates there are likely multiple, interactive factors at play.


Over the past 3 years, the DEER Project has strived to take a comprehensive approach to evaluating factors that influence population dynamics of mule deer and elk, but through recent partnerships with several conservation organizations we simultaneously have the opportunity to expand our understanding of predator-prey dynamics in the region. As expected, predation on neonates has occurred across all years of the DEER Project but has had the potential to significantly impact survival of fawns and adults in some instances. Nevertheless, we have a unique opportunity to understand in great detail predator movement and space use, and how it relates to survival of neonatal ungulates.


We have recently succeeded in garnering a sufficient sample of GPS collared individuals from two of the most prolific predators of mule deer: coyotes and mountain lions. These data, along with survival of neonates, behavior and nutritional condition of female deer, provides rarely observed links with vulnerability to mortality associated with predation. For instance, understanding whether coyotes actively seek neonatal mule deer during parturition provides context as to one of the mechanisms behind potential effects coyotes may have on fawn survival—all of this information, however, would not be possible without the use of GPS data. Hence, the lessons we can learn from a more in-depth evaluation of predator movement and space use alongside monitoring closely the behavior and performance of their ungulate prey will be a worthwhile investment and provide immense return to our understanding of factors shaping population dynamics of mule deer.


We have been fortunate to work closely with Wyoming Game and Fish Department to deploy GPS collars on 28 coyotes and 5 mountain lions throughout the Greater Little Mountain Ecosystem. The GPS data collected from two key predators along with the plethora of data we have already collected from the DEER Project provides an unprecedented opportunity to explore relationships between predators, prey, and their environment. Accordingly, we are striving to employ an additional season of field work in the summer of 2019 for the DEER Project where we hope to be capturing and collaring neonatal mule deer, monitoring and assessing vegetation on the landscape, and evaluating cause-specific mortality of adults and neonates.



Thank you to Wyoming Game Commissioner Pete Dube

mule deer mule deer conservation muley fanatic