Are Beavers the real drivers of trophic cascades in Yellowstone?

First, full disclosure.  I’ve only actually observed beavers twice–once in Escalante National Monument before it was an official Monument.  The other time a few years ago at Colter Bay Campground in Grand Teton National Park in a small backwater inlet.

But lately I’ve been thinking a lot about beavers.  It all started upon reading a new book about Yellowstone wildlife, (Yellowstone’s Wildlife in Transition). With over thirty scientific contributors, the book covers a lot of ground, and much of it demands a tedious and close read.

The general public has latched onto the story of Yellowstone’s wolves causing a trophic cascade, regenerating willow and aspen growth in the Park which in turn creates habitat for songbirds, beavers, and fish.  The short video How Wolves Change Rivers went viral, with over 15 million hits.  It’s a nice story but…

In Yellowstone’s Wildlife in Transition this notion is examined by the science community. The jury is still out and scientists are still researching and debating exactly what is happening with the landscape changes since the wolf reintroduction.  Along these lines, one chapter in particular caught my attention. It was the story of how wolves might be the ‘top down’ influence, but beavers are the ‘bottom up’ influence, and that it just might be the beaver doing most of the willow-aspen changes in the Park, not the wolf.

The ‘top down’ idea is that wolves keep elk on the move and out of the bottomlands and riverbeds where they munch new growth aspen.  With yearly munching, the aspens are stunted, never growing beyond elk munching height. Yet now, with elk moving around to avoid wolves, aspen and willows are returning.  Christine Eisenberg’s The Wolf’s Tooth expounds this viewpoint.

By the 1990’s beavers had become scarce in the Park.  Theories abound as to why–climate change and lower stream flows; overpopulation of elk outcompeted them for food–but without the beavers, riparian corridors were reverting to grasslands. Beavers need willows, and willows need beavers. Dam building by beavers raises local water tables, trapping fine sediments, and producing conditions perfect for willow establishment.  Beavers use willows to reinforce their dams and lodges.  Even after a beaver pond drains, willows establish themselves in the bare sediment. But without a high water table, these areas will eventually turn to grasslands.

Beaver dam

Studying Yellowstone’s aging plants and soil structures, scientists found that locations where willows previously were abundant on the margins of beaver ponds had fine particle soils extending up to 40 meters from the center of these streams. Today these same areas had shifted to gravelly soils immediately adjacent to the stream. This pattern indicated that the width of riparian habitat establishment along stream corridors was 20-40 times greater in 1930 than in 1990! 

Experiments were conducted caging willows and aspens to protect them from browsing in areas with wolves and elk.  What became clear was that

“if willows have insufficient water to grow, then moderating browsing by elk will not promote growth. Although willows responded to removal of browsing, their response was slow unless they had access to elevated water tables. Moreover, it was clear from the experiment that willows with adequate water could tolerate high levels of browsing. This experiment implied that the loss of beavers may dramatically slow the recovery of willows. [emphasis added]. It follows that if willows are required by beavers, and beavers require willow, then the reintroduction of wolves will not rapidly restore willows to the conditions that prevailed before wolves were extirpated.”

In the late 1990’s Montana Fish, Wildlife and Parks did a succession of beaver releases near the Park boundaries with the hopes these beavers would travel into the Park.   Several years ago I was speaking with Dan Hartmann in Silver Gate who told me that residents had spotted beaver dams around Fox Creek Campground.  On our northeast side of the Park, beavers have been extirpated since the late 1950’s.  I hunted around there for a day but couldn’t find anything.  A lot of clear cutting had gone on as well as a recent small fire started by the clear-cutting! But just a few weeks ago, I found evidence of beaver activity on Russell Creek, near where I live.  Mostly on Forest, these beavers had begun making a few dams by cutting down large aspens and some alders. But since I found no evidence of a lodge, I figured the nearby landowners had trapped and killed the beavers.  (I’ll save the phenomenon of ‘rodent hate’ for another blog post). How did these beavers get there?  They probably were from the Soda Butte creek reintroduction lineage by MFW&P years ago, traveling overland and through small drainages and washes.  Although I mourned their death, their recent presence was a good sign.

Beaver evidence on Russell Creek

Beaver evidence on Russell Creek

I will be posting more about beavers over the next months.   A fascinating story about how beavers can restore habitat and wildlife is the Martinez Beavers in the Bay Area.  Beavers in the San Francisco Bay Area!  I’ll be speaking about this and other beaver issues.  My recent ‘obsession’ is that we need these ‘bottom-up’ ecosystem restorers.  They will create moose and other ungulate habitat, bird habitat, and help stabilize creeks.

 

More on Mountain Lions

A few weeks ago I attended Toni Ruth‘s Cougar Class in Yellowstone National Park through the Yellowstone Association.  That class gave me some extra hints about tracking cougars.  I had a sense where to find tracks in my area, but identifying scraps, and finding lays and dens was another thing.  Applying what I learned, I headed out and found a kill site.  I’ve found them before, but Toni suggested that cougars usually bed down close to their kill (if its a large kill they might want to eat some more later), and also usually have a toilet within 300 feet or so.

Once I found this young deer kill in a rock crevice, I began investigating for a bedding site and a toilet.

Cougar deer kill dragged to rock crevice

Cougar deer kill dragged to rock crevice

Within 50 feet of the kill, I found the toilet.  Cats are extremely clean and meticulous.  They tend to use the same area to defecate and then make sure to cover it each time.  This toilet had obviously been used for years.  I knew the area and there’s a ravine about 300 yards to the east.  I’d found lots of cat kill evidence there before so this was a good place for this cat.

Then I began looking around for a bed site.  The toilet was on the flats, but the kill had been dragged below to a small cliff area.  I began investigating the rock edges.  Toni had pointed out how the cats she collared in Yellowstone were traveling at the base of very high cathedral-type cliffs.  I figured this cat might be doing the same.  And lo and behold I found a very nice small cave–big enough for a cat to bed down in.  Toni had told me that when I find these, to crawl inside and look for ‘guard hairs’, the white hairs on the belly of the cat.  They apparently shed easily.  Following her instructions, I found several white hairs.

Cougar bed site

Cougar bed site

Judging from the location, knowing that deer had been killed for many years in the nearby ravine, I hypothesized that this was a bed site that cat (or other cats) frequented. Toni said that cats use bed sites over and over, and that multiple cats will use them.

I returned a few days later with a trail camera and set it on the small cave.  I anticipated that if I got anything, it might be months of waiting.

Another thing I learned from the class was that a better place to site a trail camera for lions is a scrape.  This is because male lions use scrapes (a scent mark) to communicate a lot of information, especially to find females.  And a lot of other animals will visit these scrapes.  Dan Stahler who visited the class for a morning had a video of a grizzly bear taking a full days nap on a cougar scrape!

So today I went to put my camera on that scrape I found.  I stopped to check the bed site cam and look what I found.Cougar

Cougar exhibits a flehmen response

Cougar exhibits a flehmen response

Cats, including your common housecat, have what’s called a Jacobson’s organ on the roof of their mouth.  This puma was smelling what had taken place in his bed site (myself as well as my dog had been there when we placed the trail cam), then drew that scent up into the roof of its mouth for a better smell. The Flehmen response is similar to smelling but the vomeronasal organ is interfacing separately with the brain. It is usually employed for detecting sexual pheromones from the urine but may also be used for supplemental analysis of any interesting smell.

I asked Toni in her seven years of cougar studies in YNP, how many times she saw mountain lions (not counting the collaring done with dogs).  Her reply–3 times!   I still have yet to see a cougar despite all this tracking.

Tracking cougars

On Sunday we had a nice snow, so today was the day to go to one of my favorite spots for cougar tracking.  The area is a peninsula of rock, funneling into wooded cliffs that provide a corridor down to the Bighorn Basin–a perfect landscape for the perfect predator.

I started my hike with the intent of exploring an area of cliffs that I’d only approached previously from the western edges.  I wanted to see if I could climb this high viewpoint from a different angle.  Yet I soon was sidetracked by two sets of cougar tracks–a large male and another set, possibly a female.  I decided to backtrack them and see if I could discover more information.  Then, another surprise.  As the tracks led downslope into the trees by the canyon walls, I came upon a set of human footprints–a person with at least one dog.

Cougar sidetracks along a cliff edge where I decided to go around

Cougar sidetracks along a cliff edge. I decided to go around rather than risk falling down the cliff!

There’s been cougar hunters in the area since the start of the hunting season, last September.  Cougar hunting in Wyoming goes from September through March 31st.  Cougar hunting takes place with trained dogs, fitted with GPS collars.  Once a track is located (easiest done in snow), the dogs are let loose and follow their noses.  The dogs tree the cougar; the hunter uses the GPS signal to find the treed cat and then shoots it.  The trophy hunt is done.

So instead of tracking my cougar, I began tracking these human tracks to see if this cougar had been killed.  At times there were cougar tracks alone, other times hunter and cougar together. It was obvious this person was following cat tracks, but these  human tracks looked a day or two old.  Then finally I found what I was hoping for: a cougar track on top of the humans, and the cougar’s track was fresher.  With all the human and dog tracks, I lost my cougar.

Cougar print over a human boot who was tracking him

Cougar print over a human boot who was tracking him

On my return home, there he was. With only his tracks, I was able to follow him through many twists and turns–encountering several scraps.  This male was making his mark and putting out his calling card for a female.

Scrap, around 8" with a pile in the back.  Cougar pushes with his back feet his scent

Scrap, around 8″ with a pile in the back. Cougar pushes with his back feet his scent

Another view

Another view

After a lot of ups and downs, this male disappeared down a deep canyon that crosses the river. Interestingly, a friend told me he chatted with some fellows who’d been driving the nearby highway and spotted a cougar dragging his deer kill.  By crossing the canyon and river, my cougar could make his way up the mountain side.  Maybe it was the male I was following who they saw.  Male mountain lions have an average territory of 462 square miles!

Measuring this print, its shape.  I decide its a male and then confirmed by the scrap it left

Measuring this print, its shape. I decide its a male and then confirmed by the scrap it left

Big cat print

Big cat print

I am still trying to wrap my head around trophy hunters.  Mountain lions are beautiful animals–much more beautiful alive than dead. They move with perfect grace, are the most elusive predator, and left alone (see the results of a no hunting policy in California) will self-manage and have minimal encounters with humans.  We can easily live side-by-side with these predators as long as we do not fragment their habitat and/or protect our livestock wisely.  So why hunt them?

One cat hunter said it was exciting hunting a predator that backtracks and ‘hunts you’.  But that is just imaginary thinking. Toni Ruth describes mountain lions as the “Clark Kent of the animal world”; in other words, very mild mannered.  A cat that backtracks you is simply a curious cat.  And using dogs to find and tree your prey, and then simply taking your shot at a sitting animal is not hunting, but killing.  Very few people eat mountain lion.

When I first moved here, wolves were listed as protected.  A cat hunter’s dog was killed by wolves and the cat hunters stopped coming around.  But this year they are back and don’t seem to care any more about wolves taking their dogs.  The country I live in has no reported incidents of livestock being killed by cougars.  And over-hunting big males leaves a lot of adolescent males running around getting into trouble.  In short, hunting disrupts a tight cat social structure that self-regulates and keeps the cats out of human trouble.

All in all, it was another fine day of cat track hunting.nice cougar track

 

 

The Health of the Land

With the warm temperatures, the December snows are melted off in most places around here. Because of that, some friends and myself ventured into some high areas that are usually inaccessible this time of year.

The Absarokas and elk

The Absarokas and elk

A glorious day in the high 50’s (how strange for ‘winter), we began the hike without snowshoes.  Sometimes we had to venture through large drifts briefly.  Lots of elk sign but no elk visible.  This is an area where I know a large herd of elk overwinter so I expected to see them at any moment.  As we approached the high meadows, about 250 elk moved down into the valley below and up to the meadows on the opposite side.

Elk

As we watched, two wolves called back and forth from the cliffs above the elk.  Interestingly, the elk continued grazing uphill in their direction as they called to each other.  Clearly, these elk were not disturbed by the wolves presence.  I have always maintained that wildlife are more in tune with each other than humans are with them.  After a while of howling, the wolves went on their way, making distance between themselves and the herd.  Those weren’t the calls of hungry wolves and somehow the elk knew that.

elk moving up the hillside

We moved on and came to a large herd of over 30 ewes, lambs and young rams grazing.  A band of about eight rams grazed on a meadow beyond.  A second herd of over 250 elk was working their way up the hillside.

Bighorn sheep

 

Bighorn sheep

 

Ram group

Ram group

On the way back through the willows, four moose were relaxing and munching.

What a brilliant day and great sightings.  I was especially happy to see all the bighorn sheep we have this year in our area.

Moose mom and male calf

Moose mom and male calf

Tracking notes

The other morning, after a nice light new snow, I drove the dirt road.  The elk were out, as always in the early morning, feeding, in a large group of over 700.  As I continued my drive, I came to a fresh track of two wolves that had run down the road.  They weren’t wandering, but directed towards somewhere.  In short order, another wolf came trotting in from the nearby meadows. Then another, and another.  Soon the tracks clearly showed 6 wolves running alongside each other.

Over time six wolves came trotting down the road

Over time six wolves came trotting down the road

Every so often I’d stop the car, get out, and examine the track.  These were the Hoodoos, a pack of stout, large wolves with the alpha tracks measuring around 5″ long x 4″ wide.

Wolf print

They didn’t appear in a hurry or threatened, for they were all side trotting with a stride about 30″. Their tracks sometimes overlapped or meandered.  Occasionally a few of them run off the road, then return at a different location.  These might have been the pups, exploring and meandering more than adults would.

Then a strange thing happened.  It appeared that more and more wolves were ‘returning’ to the road, all traveling in the same direction.  At one point I struggled to tease apart all the tracks and I counted eleven or twelve wolves!  I knew there was no way we had this big a pack in our area this year.  There are two packs around, but they don’t travel together.  I couldn’t figure it out.

I counted around 11 or 12 wolves

I counted around 11 or 12 wolves with all the tracks in the same direction and the same freshness

Then tracks ended by running off the roadside into a field of brush and willows, a haven for a young bull moose newly kicked out on his own this year.  I saw magpies hanging on the fence by the willow’s edge. So this was what all the ruckus of tracks was about!  I realized that these wolves had made a kill in the willows, fed for a while there, then headed off, only to circle back via the road and feed once more.

A few mornings later I walked out into the willows.  I was curious if that young moose had been their victim.  Moose are scarce here, having a hard time making a comeback between diseases, the ’88 fires destroying habitat, the warm summer and winter temperatures, as well as added predators.  Moose suffer heat stress in winter when temperatures are above 23 degrees.  Since early January most of our daytime temps have been above freezing, and many days in the 40’s and 50’s.  Thinking that it’s rare to find elk hanging in dense willow cover these days, I was afraid it was this moose that had been killed.

Hoodoo wolf prowling around

Hoodoo wolf prowling around

Yet the elk had been acting strangely early in the year–I’d seen them alone, in small groups, in tight areas, feeding mid-day, and not in the larger herds I’m used to.  But in the last several weeks, their ‘normal’ patterns have returned–normal for winters here means elk moving in large bunches from 100-700 elk and feeding early morning and late afternoons.  Although elk patterns are mysterious, I’m suspecting that when the elk came down from the Park in late December this year, the wolves were late in following them and were still higher up.  But as soon as the Hoodoos got to work, the elk became the herd animals nature intended.  Unlike many wolf packs in years past that resorted to killing deer, the Hoodoos are experienced hunters and know how to kill elk.

Here's my moose

Here’s my moose

With the help of a Koda sniff, we found the leg of the animal.  Not our moose but an elk, and it looked like a two or three year old from the look of the skin.  On the way back home, I saw that moose that had been hanging out in those willows for weeks on end.  He had moved up the road to a different area.

Sometimes it pays not to jump to conclusions, but instead be patient, and attempt to tease apart the puzzle of wildlife.

Cougars, Pumas and Mountain Lions in Yellowstone National Park

I just completed a fabulous Yellowstone Association class in Yellowstone National Park at the Lamar Buffalo Ranch.  Renowned Puma expert, Toni Ruth, led the three day seminar.  After an initial morning of introduction to the cat family, we went out looking for the elusive cat and her sign.  If you come to a cougar class thinking you’ll see a cougar, then you’ll be highly disappointed.  But you might see some sign.

Our outing on day one consisted of snowshoeing down into a steep canyon. We saw no cougar sign, but did find some bear beds.  Toni pointed out what kind of areas we might find scraps.  Scraps, usually made by males to mark territory and also to signal females, consist of a cougar scenting while pushing backwards with his back feet, not unlike a dog might do.  Usually about 12″ long with two distinct marks and a pile at one end.

Where a Scrap might be under a large conifer

Where a Scrap might be under a large conifer

Early the following morning, some of us went out to Slough Creek to find wolves.  Lots of howling and some coyotes and eagles on a kill made it all worthwhile.

Hearing wolf howls

Hearing wolf howls

On the second morning, Dan Stahler spoke about the Yellowstone Cougar Project. During the ‘pre-wolf’ days, over 80 cougars were tagged in the park. Using this as a baseline, Toni Ruth did a cougar study in the park from 1998-2005, tagging 83 cougars of all ages.  During this period, wolf and elk densities were high.  Since 2005, there hasn’t been a study in Yellowstone National Park regarding pumas.  In 2014, Dan began a five year cougar study. This study should reveal some interesting data since elk densities are now much lower.  As wolves, bears and cougars compete for the same food, it will be interesting to see how these top predators deal with one another and their prey base.

Collecting cougar scat the scientific way with tweezers

Collecting cougar scat the scientific way with tweezers

Toni pointed out that cougars need to make a kill approximately every 7 days. Wolf packs need to kill every 3-4 days.  But wolves are feeding an entire pack, whereas cougars are feeding only themselves.  Cougars with kittens would need to kill more often.  Therefore, cougars kill more often than wolves.

One rumor I hear a lot in these parts is that hunting will control cougar numbers.  In fact it is just the opposite.  Adult males are very territorial, with an average territory of 462 sq. miles (220-704 sq. miles) Dispersing juvenile males need to find their own territory and can have a hard time at it.  If they are in another adult males’ territory, they can be injured or killed.  Adult males that have secured their territory will be known to the females in the area.  These females will tolerate them on a kill, and even around their kittens, which may most likely have been fathered by them.  But dispersing males are what are really the threat to females with young, as they might kill the young in order to bring the female into estrus. Therefore, when hunters are killing trophy adult males in an area, they are changing the social structure and creating a constant turnover of young males.  Interestingly Toni pointed out that in her personal experience, houndsmen who have assisted scientific collaring ‘hunts’ (where cougars are tracked by dogs but instead of being killed, they are fitted with GPS collars and released for study purposes), wind up learning so much about cougars that they abandon hunting them.

Cougar hind track measuring 2.75 x 3.25

Cougar hind track measuring 2.75 x 3.25

I asked Toni about the method Wyoming Game & Fish use to set cougar hunting quotas.  WG&F takes a tooth from hunter kills and ‘ages’ it.  Toni said that unless methods have greatly improved recently, tooth aging is not reliable and cannot accurately age a cat.

After an extensive hike with little results on the second day, we spent the entire last day hiking down to and along Hellroaring Creek.  Finally we had the luck we were hoping for.  Some cougar scat and good tracks!  While we were trying to measure the tracks, three bison were trying to stroll down our trail. Never mess with bison; so we gave them the room they wanted and lost our cat tracks.  Toni said since we were backtracking this cat, he was probably watching us the whole time.

Our class!  We had fun.

Our class! We had fun.

Finally, I put this little video together from stills from my trail camera.  I also recorded the sounds separately on a Zoom recorder in front of my house this January.

What is base line?

Driving the road early morning, looking for wildlife, gives me time to ponder questions like–why is it I see grizzly bears during the daytime in Yellowstone National Park vs. where I live just 20 miles east of the Park where they are basically nocturnal?  Bears have not been hunted outside the Park since 1975, and there are plenty of them in my valley.  Yet bears in my wild valley, like all wildlife, avoid the most unpredictable top predator–Man.

Until the hunt began two years ago in Wyoming, I used to see wolves.  In the winter, I’d see them on kills they made near the dirt road.  In the summer hiking in my valley, I had many close encounters with wolves, none of them eliciting fear.  It was obvious they were simply curious.  But since the hunt, they are no longer curious and they are no longer visible.  A good thing if they want to stay alive.

Yearling pup

Yearling pup

Today’s wildlife, and especially predators, are basically nocturnal or crepuscular, feeding, moving, hunting when Man is asleep.  I have to ask:  Has it always been like this?

Reading the journals of Lewis & Clark, they describe seeing herds of bison, wolves, grizzly bears and coyotes in the middle of the day going about their business.

“…we scarcely see a gang of buffaloe without observing a parsel of those faithfull shepherds [wolves] on their skirts in readiness to take care of the mamed & wounded”

Buffalo in Lamar Valley

Beaver, considered today to be nocturnal, were easily seen during the daytime in the early 1800’s.  A buffalo calf, unfamiliar with humans, followed Lewis around.  Game was “very abundant and gentle”.

“Immence quantities of game in every direction around us as we passed up the river, consisting of herds of Buffaloe, Elk, and Antelopes with some deer and woolves.”

According to Lewis’ account, when the presence of Man is minimized, prey and predator dance together, during the daytime.

WInter elk herd at dusk

When we study the nature, movements, and habits, of today’s wildlife, how can we know what is baseline?  What are their natural rhythms?

Coyote

Coyote during the daytime in Yellowstone National Park

Wildlife in the Park are confined to a virtual zoo, yet they have not been hunted for over 100 years [on the other hand, they are still being controlled.  For example, bison are under an agreement to be kept to around 3000 animals.  When they leave the Park in winter, they are killed to reduce their numbers.] Wildlife outside the Park are hunted and so, particularly the vilified predators, are rarely seen, moving among the shadows of the night.

Wildlife that live around cities, such as raccoons, coyotes, foxes–what we might call mesopredators–also avoid humans by wandering the streets when the humans are asleep.

Before 1492, New World numbers were estimated to be around 54 million peoples.  The pre-European native impact on the landscape reflected the cumulative effects of a growing population over the previous 15,000 years or more.  European entry into the New World abruptly reversed this trend. The decline of native American populations was rapid and severe, the biggest genocide ever. Old World diseases were the primary killer.  In the basin of Mexico, for instance, the population dropped from 1.6 million in 1519 to 180,000 in 1607 (89 percent); and in North America from 3.8 million in 1492 to 1 million in 1800 (74 percent).

So when Lewis & Clark came West in 1805, were they seeing wildlife baseline? Or just the result of a diminished native population? North American native peoples had their own rise and fall of civilizations–Cahokia, Ancestral Pueblo Culture, Poverty Point, and many others that were as equally sophisticated as the Aztecs or Mayans.  What were wildlife interactions during those times when many ancient peoples in the Americas lived in cities? Was wildlife again moving nocturnally?  Were they being hunted out?

Poverty Point artists rendition

What is baseline?  What is the natural rhythm for elk, or wolves, or grizzly bears? Today’s wildlife biologists use observation methods unknown in the past–GPS collars, trail cameras, plane flyovers, computer mapping–all very sophisticated.  But the interactions amongst predator-prey species are probably dictated more by human pressures than by each other.

When we postulate new wildlife theories, such as “The Landscape of Fear“,  what exactly are we observing?  Certainly not what Lewis observed in 1803 when wolves, coyotes, elk, deer and bison all traveled together–wolves following on the outside of these large herds.  New theories enlarge The Landscape of Fear to include not only top-down but bottom-up where the bottom has to do with beavers providing the habitat for willows and aspen rather than just elk avoiding drainages.  And scientists acknowledge that baseline is a moving target.

And so the answers to these questions will always be uncertain.  One thing I can easily observe–wildlife is more afraid of Man than they are of any other predator.  That, I believe, is an unfortunate thing.  Writer Mary Beck says in her book Seven Half-Miles from Home:

This one species has contrived to make himself feared and hated by most other creatures.  Since this fact is rubbed into my consciousness day after day by many creatures with whom I would be friends, I grow sensitive and ashamed of being one of such feared and hated beings.

 

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