Yellowstone field experience

Last week I had the great pleasure of spending a week in Yellowstone National Park with both corvid expert, John Marzluff and predator-prey dynamic expert, Aaron Wirsing.  In addition to spending an entire week with these two, I also had meetings and saw presentations from folks like the golden eagle team of Al Harmata and Marco Restani, the head researcher of the wolf project, Doug Smith, Bison expert Rick Wallen, and wolf and cougar kill expert Dan Stahler.  It was an amazing week of breath taking wildlife and in depth expertise on what’s going on in the park.  This week, I thought it would fun to take a little break from corvids and just share some of the photos I took along with the stories and biological details that go with them.

Birds
Ungulates
Predators
Miscellaneous

Birds

To kick the trip off we headed outside of Bozeman, Montana to meet up with eagle researchers Dr. Al Harmata and Dr. Marco Restani.  They’ve been doing research on eagles for more than 30 years and know more about these birds than maybe anybody.  Right now, they’re conducting an ongoing study to look at the effects of lead poisoning on  eagles.  Although lead shots have been banned in waterfowl hunting and in some states like California, in most other places lead bullets are still used for other kinds of game.  The lead fragments end up in the gut piles hunters leave behind, or in the prairie dogs or other carnivores that their shooters had no intention of taking home.  Eagles scavenge these remains and can wind up with deadly levels of lead in their bloodstreams.  Elimination of lead from bullets will likely be a necessary step to protect eagles, though I expect a robust fight from the NRA and some hunting communities.

For corvids, spring time means nesting time and the magpies were busy at work.  Unlike crows and ravens which build more traditional looking nests, magpies make nests with roofs, further protecting them from predators.  If that’s not cool enough, magpies are known to build several of these dome nests and have been observed moving both eggs and chicks between them.

Seeing peregrine falcons perched along the 520 bridge on my way to school is always a treat, but there’s something about seeing them in this setting that’s all the more spectacular.

At lunch time we were greeted by John’s special raven friend, Big Guy, which has been visiting him in the park for the last 15 years.  He and his mate were also busy nest building though we were unable to locate it.

Mountain bluebirds were such a spectacular addition of color to the park, and I was super lucky to be in the right place at the right time to snap this photo.

Ungulates

When we first arrived to the park, we were surprised to be greeted by pronghorn.  John has been leading classes to Yellowstone for 15 years and had never seen them as far into the park as we did.  Pronghorn aren’t adapted to run very well in deep snow, so they generally avoid the higher elevations in the park until later in the year. The snow melt came incredibly early this year, however, allowing them to penetrate further into the interior of the park than usual.  While the level of early snow melt we experienced isn’t unheard of, it was unusual and fit the models that predict increased drought in this area as a result of climate change.

Bighorn sheep were prolific across the park.  In the winter and spring, male bighorns form large groups while the ewes and lambs heard up to do their own thing. I never got tired of seeing those big curls!

Bison are truly the iconic ungulate in the park.  Theirs is a story of an amazing comeback, and one that’s really not so different from wolves.  As of 1902 there remained only 23 bison left in the park, and but thanks to ranchers and the US Army administrators of YNP, new animals were brought in and over the next 50 years that small population grew to over a 1000 animals.  Now, the park supports about 4000 animals, and is considered the only place in the country that has both maintained bison since prehistoric times, and supports non-cattle hybridized bison.

Right now, bison regulation within the park is subject to much debate due to the presence of brucellosis.  Brucellosis is a bacterial infection that was brought when settlers first introduced cattle to the west.  It results in the abortion of calves in animals like bison, elk and livestock.  It’s transmitted by contact with an infected mucous membrane, which generally happens when curious animals touch and smell the aborted calves.  Although it’s not fatal to the mothers, the aborting of calves represents a potential economic threat to ranchers.  Although elk are also important vectors of this disease, a rancher we spoke with echoed the opinion of the ranching community at large in saying that bison are the main problems and their departure from the park needs to be controlled.  As of 2002, the Sate and Federal government developed an inter-agency management plan to control bison and the spread of the disease, which basically means that many (think in the thousands) of animals are killed once they cross the boarder.  Lead park bison biologist Rick Wallen described to us the controversial nature of this tactic which results in, one the one hand, folks from the ranching community saying there isn’t enough being done, while on the other, members of the public decrying the park for killing such an iconic species.  Despite these culls, however, the park maintains a stable population of bison, which other than run-ins with lakes and geothermal features, are basically free from predation apart from one particular wolf pack which occasionally manages to take one down.

One of the most interesting insights from Rick was the observation that bison both engage in what looks like altruistic behavior, like the time he witnessed a heard protect an injured female from wolves, to completely brutal behavior like the scene my classmates and I had the serendipitous opportunity to witness.

We happened upon this scene when checking the area for signs of a bear we had heard was scavenging some bison carcasses. Although we didn’t see the bear, we quickly noticed that there was a bison calf trapped in the water, and not too far from drowning by the sounds of its breathing. The banks of these lakes are incredibly slick, and it can be impossible for an animal to get out. We watched with bated breath, conflicted between rooting for the bison to make its escape and for it to drown, as that would mean an almost guaranteed bear and wolf sightings the following days. Finally after about 10 minutes the calf managed to pull itself from the water. While all this was going on, its heard had been nearby and quickly after the calf escaped began to approach it. We were all expecting a Disney style reunion but to our shock the entire heard proceeded to haze the calf! They pushed it about 100 m down the valley before finally relaxing their assault and letting the calf rest and start to graze. Since we didn’t see bears the next day, our best guess is the calf managed to regain its strength and make it through the night.

Although much of our time in the park was dedicated to simply looking for, and observing wildlife, we also collected a couple of different kinds of data while we were there.  For the last 7 years this class has been conducting “elk follows” which means that we select an individual elk in the different parts of the park and record its activities for 15 min.  Later, we will use this data and match it up with data from the Wolf Project to ask questions about elk behavior, condition, and spatial use in light of the presence of wolves.  This big bull was taking a little rest and is a great illustration of the hardship of winter.  You can clearly see the low fat reserves on its rump, as evidenced by the outline of its spine and pelvic bones.

This bull is a good example of one that’s already lost its antlers, and it’s probably feeling a little lighter than its 5-point companion, since elk antlers can weigh up to 40lbs!  Antlers are the fastest growing tissue and in the height of spring and early summer they can grow up to an inch a day.  One of our faculty members, Aaron Wiring, told us an incredible story of seeing a big 6 point bull being chased by wolves in an earlier trip, only to loose one antler during the chase. A little lopsided, the bull managed to fend them off until it was finally cornered against a tree when, you guessed it, the second antler fell off.  It was all over soon after that. Talk about bad timing!

Predators

A coyote makes off with the leftovers of a bison carcass.  Coyotes are often killed by wolves, and they need to be extra mindful when in open spaces near kills sites like this.  Why wolves are so predatory towards coyotes and not foxes is something of a mystery.

One of my favorite experiences while in the park was seeing the wolves.  There’s just something about seeing such an iconic animal that lifts your spirit.  The reintroduction of wolves was, and still is, incredibly controversial.  There’s no doubt that their presence on the landscape is a threat to ranchers and pet owners alike, but I was inspired by our talk with Hannibal, a rancher who lives adjacent to the park boundary.  Despite loosing three dogs and many sheep and calves to wolves, he maintains his position that they are a necessary part of the Western landscape and deserve a place along side he and his family.  After his daughter, Hilary Zaranek, started range riding (rounding up and sleeping with the heard at night) predation by wolves dropped to nearly zero and their three current dogs seemed very happy to me.  By shifting the ranching paradigm to one where multiple ranchers join herds and share space, range riders become a sustainable and economical option for ranchers.  Hannibal and Hilary are the forefront of this shift and their dedication to the presence of wolves was awe inspiring.

While we were in the park we were privy to some pretty special changes going on within the packs. Inside the park, wolves are killed almost exclusively by other wolves.   Recently, the alpha male of the Lamar Valley pack was killed by members of the competing Prospect pack after he confronted them.  His death put the alpha female in an incredibly precarious position since she will be unable to hunt after she gives birth to her dead mate’s pups and in a few weeks.  Although her 6 current pups are nearly a year old they are still too young to provide for her during this time.  As a result, she is attempting to court 4 of the male members of the Prospect pack in an effort to gain a new alpha male that will help raise her pups.  Unlike lions which will kill the cubs of a competing male, wolves will help raise the former dad’s pups after they take over.  Some readers may even be familiar with the famous story of 8, the hero ‘little wolf” who did just this.  While we were in the park the female appeared to be courting a spectacular grey male, but shorty before we left we learned that he fell out of contention.  Who the next alpha male is is up to the alpha female, and only time will tell who she chooses.

The effects of wolves in the park have been profound and their necessity to maintain a balanced and healthy ecosystem is unquestionable.  For more information on the wolves’ effects on the Yellowstone ecosystem check out this Ted talk.

One of the most interesting things we did was meet up with wolf expert Dr. Dan Stahler.  He and fellow carcass expert, Kai, lead us to a recent cougar kill and described how to identify kills as either wolf or cougar and showed us the kinds of data they collect off such kills.  Key signs off cougar kills are puncture marks around the throat, neat, cleanly picked bones, and characteristic caching (or covering and hiding) of the carcass.  Wolf kills, on the other hand, are not hidden, show signs of hemorrhaging around the animal’s back legs, and the carcasses are found dismembered.  This particular cow elk was killed and partially eaten by a cougar before being discovered by wolves and other scavengers.

Miscellaneous

A badger skull found while hiking the bighorn lambing grounds on the edge of the park boundary.

On our last day I spotted a couple of yellow-bellied marmots, marking the fist time John has seen them inside the park during this trip.  I’ve never gotten such a good look at these little animals and I must say they’re very pretty!

Antler drops are an important source of calcium for many animals in the park, and this particular one shows its age with a beautiful patina of lichen.

A bison carcass lays peacefully in its resting place of Lamar Valley.