This entry details a portion of my thesis work at the University of Alaska Fairbanks, and is intended to communicate the findings of that work in a four part series. You are reading part four examining the likelihood of competition between wolves and humans. In order to make the article concise, you may review the general background of this work in part one. I have truncated the background and methods of this work and focused on a portion of the results.
In parts two and three of this series I have been examining where humans in the Yukon Flats, Alaska are traveling to harvest moose and where/how wolves are traveling to harvest moose. A key finding of human access was that humans are mostly operating within 1500 meters of navigable water. During our wolf study I found that travel was based around river corridors. Based on this, I will conclude this series of articles by examining the “Beaver Creek” pack which overlapped strongly with navigable water.
I wanted to begin to understand the likelihood of competition around navigable waters for moose between humans and wolves. Remember, moose exist at extremely low densities and humans and wolves depend on them as a food resource. Therefore, I believe understanding competition is particularly important. To understand the likelihood of competition, I applied my model of human access and overlapped it with wolf locations. I found that 75% of wolf use locations fell within the human access model.
My analysis does not contain temporally overlapping data. Wolf habitat selection may differ in September and October when humans are hunting moose. Wolves could also rely on other prey species other than moose during that period. Also, predation in the Yukon Flats extends beyond wolves. Bears take up to 85% of moose calves each spring. As such, my conclusion is just the beginning research for future biologists in the region. A complete analysis would encompass all predation on moose, be spatially and temporally overlapping, and would evaluate how many moose which are predated could be taken by humans. I hope you have enjoyed this four part series! A full copy of the thesis can be obtained by contacting me. Feel free to do so!
This entry details a portion of my thesis work at the University of Alaska Fairbanks, and is intended to communicate the findings of that work in a four-part series. You are reading part three examining wolf movement in the Yukon Flats, Alaska. In order to make the article concise, you may review the general background of this work in part one. I have truncated the background and methods of this work and focused on a portion of the results.
Wolves are highly studied because they are charismatic, exhibit interesting pack behaviors, and are a key predator in the systems where they exist. Their behaviors including movement speed, movement distances, number of prey killed, and travel distances have been well documented in high prey-density systems, but practically no information exists on these behavior in low or very-low density systems. In an attempt to rectify that, a study was initiated in 2008 to understand the kill rate of moose by wolves in the Yukon Flats, Alaska, where moose are held at low densities (<0.20 per square kilometer) by predation. In an interesting twist, that study found wolves are maintaining kill rates (moose per wolf per day) similar to wolves in high prey density systems. Certainly these results counter what I would predict and lead to a natural question – how are wolves accomplishing such high kill rates in low-prey densities? A known mechanism is that wolves in the Yukon Flats keep small pack sizes to cope with low densities of prey; if you have fewer wolves in a pack, more nutrition is available per wolf during each kill. However, if wolves were traveling further or faster in this low prey-density system was unknown. I predicted that wolves in a low prey density system were traveling further, but not faster than wolves in a high prey-density system to maintain these kill rates. I also predicted they were selecting for river corridors when traveling.
To understand wolf movement, I used the same dataset from the 2008 kill rate study. It was composed of Global Positioning System (GPS) collars on six packs. Thanks to diligence in the kill rate study, I knew where kills occurred along each of the paths. For each pack, I characterized if the wolves were traveling, resting, at a kill site, or revisiting a kill site. These behaviors gave me enough information to calculate the rate of speed they were traveling, the distance they were traveling, the number of days traveling to make a kill, and how long they spent at kill sites. I also using a Generalized Linear Mixed Model to understand what landscape features were important for traveling wolves.
I found some interesting results, and put them in context of 16 comparable research papers of movements of wolves in high or medium prey-density systems. I am presenting the most applicable comparisons from the literature review (i.e., systems where moose are prey and studies where GPS collars were used) here. I found search time was slightly longer and search distance was 2.4 times greater in my low prey-density study area. Search time and search length are correlated together given that wolves are (almost) always hunting when moving. Due to that relationship, the search time is expected to go up as search days goes up. I found no evidence that wolves were handling prey longer or traveling faster in the low prey-density system. Those results were not surprising as one researcher found that handling time of moose was not significantly different among packs which varied in size from 2 – 20. Since wolves were not traveling faster in our system, it is probable that regardless of prey density, that on average wolves travel at their maximum comfortable speed that maximizes efficient travel.
I also found that wolves were utilizing river corridors and that they were selecting strongly against brushy habitat. In the Yukon Flats, that means they were selecting against thick stands of alder and willow. This was similar to previous studies where they found that wolves were able to travel 2.8 times faster if they used a river corridor rather than moving through a brushy environment. By using rivers, wolves were traveling faster and are likely taking advantage of increased prey density along river corridors.
The results of this work have some useful applications in helping us broadly understand wolf behavior. First, wolf territories are very large within low prey-density wolf systems. The mechanism that creates these large territories was unknown, but long-distance movements by wolves would create large territories by default. Next, back in the mid 1980s a researcher suggested that 0.20 moose per kilometer squared was the lowest density that wolves could persist at. Within the Yukon Flats, they are already persisting at lower densities than that, and since they are able to extend their travel distances to maintain kill rates it seems a minimum prey-density threshold could be much lower. A final implication of this work is that managers should expect wolf territories to increase in size if prey density decreases. In other systems (for instance deer in the mid-west), wolf territories should inflate in size as they move further in search of prey.
I look forward to presenting part four to you soon, which ties together moose hunting by wolves and humans by starting to understand the likelihood of competition.
For the last 2.5 years in fulfillment of my Masters in Wildlife Biology at the University of Alaska Fairbanks, I have been researching the biological and human component of two key moose hunters (wolves and humans) within the Yukon Flats. I am happy to say that the full thesis is is completed and that I will be graduating in December! In my eyes, a critical next step is to make the results of this work public. Hence, I will be dedicating four blog entries to the subject. This first installment will introduce the biology of the region, study area, and my research questions. My next installment will examine access of subsistence hunters to moose within the region. Following that I will look at movement of wolves in the region, and I will conclude by looking at areas were the likelihood of competition between wolves and humans for moose is highest.
I conducted my research on human hunters and wolves in the Yukon Flats, Alaska. The predator-prey relations in Yukon Flats are unique because wolves and subsistence users pursue low-density moose that are held at a low-density equilibrium from predation. In fact, moose are at some of the lowest densities in the world (<0.20 moose per square kilometer).
Broadly I was interested in:
How do human hunters and wolves utilize their environment when pursuing moose?
How does understanding space use and movement and of humans and wolves pursuing moose help us understand competition for a scarce resource they rely on?
The Yukon Flats National Wildlife Refuge is located in central Alaska, and extends nearly 220 miles east to west and 120 miles north to south. It falls directly into a the boreal forest, which means if you walk around that you’ll find birch, black spruce, white spruce, alder and willow. Its namesake is the Yukon River which bisects the Flats, and the huge watershed of the Yukon River is fed by a plethora of rivers. In short, it is a water dominated system.
Within the Yukon Flats there are several communities that are defined by their reliance on the land to harvest food, fuel, and fiber. Their subsistence lifestyle provides up to 85% of the resources they use including but not limited to moose, fish, and waterfowl. Since moose are such low densities but are critical for humans and moose, it is interesting to research how moose are pursued, and where the likelihood of competition between humans and wolves in the highest. Answering any of those questions pertinent for managers. My thesis integrated spatially explicit (i.e., locations) datasets of moose (Alces alces) hunters and of wolves (Canis lupus) to ultimately evaluate how two predators pursue a common resource, moose.
To this end, Chapter 1 of my thesis will be the second installment on this blog and focus on quantifying rural hunter access in the Yukon Flats, Alaska, through spatially-linked interviews. I chose this research topic because previous studies have only qualitatively surmised use area for subsistence resources by drawing boundaries around use areas. However, a quantitative approach can yield firmer management information. My novel approach provided pertinent insight into resource use for our system and created a method that may be applied to other systems. Using results generated from subsistence hunter interviews, I applied a model of access to moose hunting areas. Harvest reporting is low among the subsistence communities in our study, and from our results we generated an estimate of harvest based on game densities similar to the best data available on reported harvest. As such, my method may provide an alternative to, or supplement, harvest-ticket reporting.
In Chapter 2, I characterized movement paths (i.e., hunt paths) between moose kills by six packs in the Yukon Flats. The results of that work will be the third installment on this blog. The movements of wolves have been studied and documented in many high prey-density systems, but almost no information exists on their movements when prey is just dense (<0.20 /km2) enough for wolves to survive.
Finally, I will tie what I learned about wolf movement and human access to examine where competition between humans is the most likely. At that time, I hope to provide a full copy of the thesis for comprehensive reading of the research. I look forward to sharing this information with you, please feel free to ask questions!