Wolf-Beaver Update #7

The field season for this project ended just a few weeks ago in early December. As such I wanted to write two more updates (a part 1 & 2 if you will) summarizing the field season and what we were able to accomplish. My apologies for the lack of updates this fall but hopefully this will give you a good idea of how the fall and the entire field season went.

As stated as one of the project goals our aim was to determine what factors impact the extent to which wolves consume beavers. We hypothesized that as the beaver density in a pack's territory increased the amount of beaver consumed would increase. To accomplish this goal we collected wolf scats from April until the end of October. In total we collected 2,531 scats which is a LOT! Most of these scats were collected by myself and project assistant, Austin Homkes, who volunteered roughly 1,500 hours of his time to the project this year. Without him, this project would never have been possible and I am indebted to him for all the hard work and hours he put in cheerfully. Sean Johnson-Bice was also a huge help throughout this project in various aspects from collecting scats, cleaning scats, going to rendezvous sites, collaring wolves, etc.

 

Photograph #1: Austin Homkes, the best research assistant one could ask for! Here Austin is examining a the skull from a moose carcass we found. The moose had died in the spring (it was a bull but had no antlers yet) but it is uncertain whether it was from disease, starvation or wolves. Either way, wolves had fed on the carcass as bones had been scattered about and wolf scat was abundant near the carcass. It is not uncommon for wolves to scavenge on carcasses of animals as it is easy, free food.

Of the scats that we collected approximately 1,900 are adult wolf scats and 600 are pup scats. I have identified all the prey remains in each of these 2,500+ scats and am currently working on analyzing the data and determining the diet of each pack. While I have not yet determined the specific diet of each pack yet, I can report on the general trends in pack diet throughout the ice-free season.

In April and May, the wolves are eating primarily beaver and adult deer. This is likely due to the fact that beavers have just made it through the long winter and need to come on land for food. Beavers are also putting in significant effort to repair their dams and keep all the winter runoff from escaping. Because of this, beavers are vulnerable to wolves. At the same time, the grasses and plants are beginning to green up with the spring and thus deer begin to have more nutritious food available which increases their general physical condition which in turn increases their ability to escape predators.

 

Photograph #2: Beavers in spring until fall are working hard to maintain the water levels in their ponds which usually includes lots of work on their dam. Here you can see a lodge in the middle of the photo with the dam covered with growing grasses. The water level is right up to the top of the dam.

Predation on beavers peaks in May. Around the end of May, deer fawns are birthed and suddenly an easy, abundant new prey item is available across the landscape. As such, wolf diet changes drastically and in June wolves are primarily eating deer fawns. Wolves continue consuming deer fawns but the extent to which they do decreases over the summer as fawns become older and more capable of escaping predators. Thus in June and August we start to see wolf diet become a bit more diverse with wolves in some packs consuming significant amount of fawns, adult deer, beavers, snowshoe hares, small mammals and/or berries.

 

Photograph #3: In late spring and early summer fawns are birthed and thus become a food source for wolves. Fawns primarily use camouflage to evade predators when they are younger but as they grow older they gain the ability to escape predators.

When the fall comes around wolves are primarily eating deer and beavers. I should note that it is possible to tell the difference between fawn hair and adult deer hair in wolf scats from May until August as fawns have really soft downy hair and adults have coarser hair. However, in September when deer get their darker hair, it becomes impossible to distinguish the two and thus we can only say that a deer was consumed (based on other studies 30-50% of the deer wolves consume in the fall are fawns). In September predation on beavers and deer is pretty even but by the time October rolls around wolves are primarily focused on eating deer. This is curious because in October beavers are foraging like crazy to build up their food cache (A food cache is a pile of sticks and limbs that beavers stash right next to their lodge in the fall. They can then access this pile from under the water once the lake freezes over thus having food to get through the winter- see photo below). This foraging would put beavers at high risk of predation but it seems that wolves are more focused on deer. Much of this is likely due to the fact that the wolf packs are traveling as a unit in October as the pups are mature. As a result, a deer provides much more food for the pack than one beaver and therefore wolves select for deer.

 

Photograph #4: An aerial view of a food cache next to a beaver lodge. The lodge is to the lower right of the island with the pine trees and the cache is to the left of the lodge.

All of this is very interesting and provides an understanding of wolf diet in an ecosystem where deer and beavers are abundant. The next months I will spend determining what the exact diet is of each pack and the factors that impact the extent to which wolves consume beavers.

One critical aspect of this project was attaching radio collars to wolves. Without this it would be impossible to know the pack boundaries, where den and rendezvous sites are, or areas that wolves frequent often. Part of the crowd-funding money raised was to purchase a GPS-collar for this research. This collar was put on the first wolf we collared in June (pictures are in a previous update). In addition to that collar, we had three other collars that we were able to put on wolves. As you can see from the photo below these collars helped us delineate pack boundaries and much more. Thank you for your donations to this research. We made sure your donations were put towards the actual research we were conducting and as such you can say that you made this awesome project happen!

 

Photograph #5: These are the five packs we were studying this year. The lines represent the path traveled by the wolf in each pack that has a GPS collar on. From this data we can clearly see pack boundaries and pack territory size. I think this is such a cool photo because it demonstrates how wolf packs are distributed over the landscape.

 

Photograph #6: A wolf we attached a GPS collar to in August. Without GPS collars on wolves this project would have been impossible as the high intensity location information we get from these collars would be impossible to get any other way.

So this concludes part 1 of my final update. I will post part 2 later this week. As always feel free to send me a message with any questions you might have the project and thanks again for all of the financial support of this project!

 

Photograph#7: The golden tamaracks across a remote lake in the park. In the fall the tamaracks turn a smoky gold and provide beautiful color to the rugged landscape.