It was early June, and I had just come into Lamar Valley to see every wildlife watcher’s dream: the Junction Butte pack hunting bison on the valley floor. We pulled over the car, set up the scopes and spent the next two and a half hours watching the back-and-forth battle of wolves pushing bison herds and chasing the young, and then the bison mounting a counter charge and causing the wolves to retreat to a safe distance. After many nearly successful attempts by the Junctions, and a well-placed kick from a female bison, the pack moved off to bed down through the heat of the day. Perhaps they would try again later, but this attempt had been thwarted.

Although the chances of witnessing a predation event are relatively low, the details of predator-prey relationships in the park are a focus of the Yellowstone Wolf Project, Cougar Project, elk research and the Elk Calf Study. This team of scientists monitors Yellowstone’s predators and their effect on prey. In 2024, the team spent 4.5 months across the year studying predation. They were able to identify over 260 different kills, 211 of them from wolves, and 56 of them from cougars. While these 267 kills likely don’t cover every single predatory event throughout the year, they act as a very good representation for what Yellowstone’s wolf and cougar diets looked like. Of the carcasses sampled, 82% of all wolf kills were made up of elk and bison and 67.9% of all cougar kills were made up of elk or deer. These studies have also revealed that predators are disproportionately targeting younger prey, as well as female prey.

While those statistics are interesting, consider the implications for what they mean in the context of the ecosystem. Within wildlife biology, there is a concept known as carrying capacity. This concept states that there is a certain number of animals within a species that an ecosystem can support. Here in the park, the current population of wolves is around 100 adult animals, and it’s been fluctuating around that threshold since 2008. This 100-animal population size, or carrying capacity, is influenced by a number of factors, including disease transmission, competition with other wolves, and food availability. For cougars, current estimates put the population somewhere between 34 and 42 individuals, with carrying capacity likely near that range.

If we look at the population graph for wolves over the last 30 years, a very clear early spike can be seen in the early 2000s. This “overshoot” of the carrying capacity is common when a predator is reintroduced to a landscape. Oftentimes, in the absence of predators, and with wildlife management norms of the twentieth century, it was common for prey species, like elk, to overpopulate landscapes, and have few ecological controls. This was the situation in the northern range of Yellowstone in the 1990s when the northern elk herd numbered upwards of 17,000 individuals. With an abundance of food on the landscape due to this overpopulation, wolves were able to quickly reproduce and expand their population to over 170. However, by the late 2000s, elk populations started to return to a more sustainable level, not only because of predators returning to the landscape, but also because of a variety of management actions and circumstances. These included a recovery of bear and cougar populations, late season cow elk hunts outside of the park, a prolonged drought and series of severe winters, and competition with increasing bison herds. As elk populations fell, other ecological stressors, such as increased competition with other predators caused wolf populations to slowly decline and level out to the stable and healthy population we see today.

A beautiful thing about carrying capacities is that in a healthy ecosystem, carrying capacities exist such that predator and prey populations become very closely tied together. In years of abundant plant growth, elk calf survival might be higher than normal, and therefore the prey population could increase. This could cause a connected response of predators with more available food in following years leading to higher wolf and cougar survival and perhaps their population increasing. As the prey population begins to fall once more, the predator population will follow. In a healthy ecosystem, these populations exist in a harmonic balance, oscillating above and below the carrying capacity for their species. The predation and population dynamics of wolves and cougars of Yellowstone teach us that beneath every action, every situation, and every population we find in the park, there is a complex web of relationships, interactions, and interdependence.

It’s this complexity that I find brings me back to wildlife watching. Being out there, watching wolves hunt is an experience unlike anything else I have experienced. The range of emotions that are felt when, for example, you watch a wolf pack sneak off with a newly born bison calf can be overwhelming. The pure excitement for the pack, and honestly some underlying sadness for the life the calf didn’t get to live. But, at least for me, understanding what predation means for the landscape, and health of a wild ecosystem, like Yellowstone, acts as a certain type of centering force. It allows me to refocus on the now, and it’s what keeps me waking up at 3:30am to get out there for the chance to see it all again.

by Kyle Wonders, Yellowstone Forever Institute Lead Field Educator

Feature Photo: Lead Field Educator, YF / Amanda Evans

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June in Yellowstone is often called the season of babies—wobbly-legged bison calves, wide-eyed fox kits, clumsy bear cubs. It is easy to view this time of year through a sentimental lens. And in many ways, it is heartwarming. But look a little more closely, and something deeper begins to emerge: this is not just a season of cuteness—it is a season of recalibration. Yellowstone in June is a landscape fine-tuning itself, adjusting its balance in real time through the presence of its youngest inhabitants.

These animals are more than symbols of spring; they are agents of ecological change. Their birth triggers shifts in behavior, movement, and energy across the park. They are not merely learning from the landscape—they are influencing it, sometimes profoundly.

Take marmot pups, emerging cautiously from their burrow where they have spent the past several weeks. Their presence is more than a mark of survival—predators begin to take notice and alarm calls echo across talus slopes. The pups’ grazing alters plant growth, which in turn affects pollinators and soil structure. One tiny mammal, in their first days above ground, sends quiet ripples outward that shape the ecosystem in subtle and accumulating ways.

Overhead, cliff swallow colonies come alive beneath the eaves of rock outcroppings and bridges. Dozens of mud-cup nests contain chicks whose survival depends not just on the dedication of their parents, but on the synchrony of the system itself. Insect blooms must arrive on time. Temperatures must rise steadily. Water levels must hold. Even large animals, like bison, play an indirect role—stirring bugs into the air with each step. From the outside, it may look like chaos, but at its core, it is coordination.

Then there are the lives we rarely notice at all. Tadpoles wriggle through snowmelt-fed puddles, racing against evaporation to complete metamorphosis. Young long-tailed weasels begin testing their speed and cunning, emerging as tiny, relentless predators. Their actions may be small in scale, but they shape prey populations and ripple upward into larger trophic dynamics. Even the smallest young have a role in maintaining the equilibrium of the whole.

Predators, of course, are tuned into this season as well. Young coyotes and foxes hone their skills on vulnerable prey. Grizzlies target elk calving grounds with precision, altering the behavior of entire herds. The emergence of young is not just a passive event; it is a catalyst that redefines how the ecosystem behaves for weeks, even months.

In this way, June is not just a moment of birth—it is a test of timing, instinct, and adaptation. The park doesn’t simply awaken in spring; it reorganizes itself. With each fledgling, each fawn, each den of kits or pups, Yellowstone is updating its internal systems—revising, responding, evolving. The nursery is not separate from the wild; it is the wild, doing what it has always done: preparing for whatever comes next.

To witness this season is to observe the park thinking. Not consciously, of course, but dynamically—responding to snowpack, temperature, moisture, daylight, and species behavior with precision and subtlety. It is a time of movement and vulnerability, of possibility and risk. And in the quiet moments, if you pay close attention, you may begin to feel it: the whole place humming with the fragile, determined pulse of new life.

Photos:
Feature: NPS / Jim Peaco
Others: NPS / Jacob W. Frank

The post Naturalist Notes: Nursery of the Wild appeared first on Yellowstone Forever.

In Yellowstone, the sage steppe supports some of the first signs of new life including the nesting birds of spring. As life returns to the limbs of the sagebrush a nursery takes shape. The newly revived Sagebrush, also known as Artemisia tridentata, a member of the Asteraceae family, will support a variety of songbirds in their pursuit of bringing forth the next generation. The sagebrush provides shelter as well as a cornucopia of insects, and nesting material. However, some birds prefer a scrubbier bush known as rabbitbrush. Equally as important to the sage steppe nesters. Rabbitbrush, also known as Ericameria nauseosa– part of the Asteraceae family, provides habitat for bird species that nest on the ground. As snow melts away the first birds in the ecosystem chose the dry sagebrush canopies for their nursery’s.

The Brewer’s sparrow is a common early arrival on the landscape that seeks out sagebrush. The Brewer’s sparrow arrives in the ecosystem in April and May looking for sagebrush and territory that will support new broods. Learn more about this bird and its unique nesting choices. The Brewers sparrow males start erupting in song shortly after their arrival as they defend new nesting territory and mates. The complex song of the Brewer’s sparrow can be heard into late July, but once chicks have successfully fledged those songs will taper off.  Through careful selection the Brewer’s sparrow chooses which sagebrush will support their nests as that can determine their success and hopes of bringing forth the next generation… Brewer’s sparrows tuck their nests against the trunk of a sagebrush, no more than about four inches off the ground, trying to conceal its precious blue-green and brown speckled eggs. Often in one clutch a Brewer’s sparrow will have between 3-5 eggs and may have as many as two clutches in one season. As the adult Brewer’s sparrow pair waits for the arrival of chicks, they will try to trick potential predators leading them away from their nest as they flush away low to the ground. Sometimes when flushing off the nest they will pretend to have a broken wing to be more enticing for predators, so they don’t pursue the nest. Between eleven and thirteen days of incubation will pass before the first hatchlings emerge, it’s a time of anticipation and hope. The springtime nests of songbirds, such as the Brewer’s sparrow, act as a symbol for new beginnings brought with the changing of the seasons.

Spring is often characterized as a season of optimism and growth; in Yellowstone this is evident with the welcoming of new birds like the Brewers Sparrow. The beginning of spring foreshadows the summer season to come, with the influx of new life into the ecosystem Yellowstone comes alive after a long period of dormancy. As you visit this remarkable ecosystem, don’t forget to keep an eye out for species like the Brewer Sparrow that are often overlooked as harkening in the changing seasons.

Article and nest images by Abbey Thomas, YF Field Educator
Featured image: USFWS, Tom Koerner

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In Yellowstone, we are fortunate to be home to two species of bears: grizzly bears and black bears. Grizzlies are found in only a few isolated regions in the lower 48 states—the Greater Yellowstone Ecosystem (GYE) and northwest Montana—while black bears have a wide range across the entirety of the United States. There are currently somewhere around 700 grizzlies in the GYE. Though an exact number is unknown, black bears are considered common in Yellowstone.

You can help protect the bears of Yellowstone

Sponsor a Bear Box

For most visitors, there is nothing quite like the excitement of seeing a bear in the wild. Many come to Yellowstone solely to see the park’s remarkable wildlife, and bears are often at the top of the list. While grizzly bears are typically much larger than black bears, they can at times be difficult to tell apart.

Whether we are talking about the distinct visual characteristics of the bears, or simply how to distinguish one track from another, we’ve put together some tips and stats to help identify both.

Courtesy of NPS

 

Grizzly Bear

NPS / Neal Herbert

Scientific Name: Ursus arctos

Color: Varies from black to blonde; frequently with white-tipped fur giving a grizzled, “silver-tipped” appearance. In the Yellowstone ecosystem, many grizzly bears have a light brown girth band.

Height: About 3-1/2 ft (1.0 m) at the shoulder.

Weight: Male: 216-717 lbs (98-325 kg); Female: 200-428 lbs (91-194 kg)

May live 15-30 years.

Quick identifier: Rump lower than shoulders.

 

Black Bear

NPS / Neal Herbert

Scientific Name: Ursus americanus

Color: Varies from pure black to brown, cinnamon, or blonde; in the Rocky Mountains, approximately 50% are black with a light brown muzzle

Height: About 3 ft (0.9 m) at the shoulder

Weight: Male: 210-315 lbs (95-143 kg); Female: 135-160 lbs (61-73 kg)

May live 15-30 years.

Quick identifier: Hump usually absent, rump higher than shoulders.

 

Bear Safety

• Give bears space. Keep at least 100 yards (93 meters) from bears at all times and never approach a bear to take a photo.
• Carry bear spray and know how to use it.
• Hike in groups and make noise. While hiking on a trail, periodically yell “Hey bear!” to alert bears of your presence.
• Do not travel in areas closed for bear management.
• Never feed bears.
• Stay with your stuff. Do not leave packs or bags containing food unattended, even for a few minutes, as bears learn new food sources quickly.
• If a bear approaches or touches your car, honk your horn and drive away. We want to discourage this behavior for the bears’ safety and yours.

 

Sources and resources

https://www.nps.gov/articles/bear-identification.htm

https://www.nps.gov/articles/yell-wildlife-bear-differences.htm

https://www.nps.gov/yell/learn/management/bear.htm

BOOK: Bears of North America by Stan Tekiela

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The Winter Wolf Discovery Lodging & Learning package focuses on learning about wolves, and other exciting wildlife, along Yellowstone’s famous northern range. Winter is prime time to view wolves in Yellowstone, and this package is designed to take advantage of this rare opportunity. A Yellowstone Forever field educator will share up-to-date information about Yellowstone wolf biology, behavior, and ecology throughout daily outings. Each evening, participants will return to their comfortable accommodations at the Mammoth Hot Springs Hotel.

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The first sign of spring is a flash of blue.

Mountain bluebirds

Long before the snowpack begins to shrink, typically in the first week of March, Mountain Bluebirds appear in Yellowstone, launching a new year’s wave of spring migration. I saw my first bluebird around Mammoth on March 10 this year, an exciting moment that foreshadows all the phenological firsts throughout the year: the first grizzly of the year (4/1 for me), the first bison calf (4/8), the first wildflowers (Sagebrush Buttercups 4/9), and countless other moments worth celebrating as Yellowstone comes alive and tilts back toward summer.

Early spring is often a time of yearning. The first warm days after months of freezing ignite a desire for cookouts, camping, and all the adventures we associate with summer, even though snow remains throughout much of the park through May and even longer in the high country. Spring in the Northern Rockies can bring all four seasons in a day; the only guarantee is mud. So, in this interlude between skiing and hiking seasons, I count each new bird species as a promise of things to come.

Sandhill cranes

Our earliest birds show up in March. First the Mountain Bluebirds, then American Robins soon after. This year, they appeared in Gardiner a day later (3/11), and then slowly spread up into the park over the next few days. By March 18, Red-winged Blackbirds and Sandhill Cranes had returned, their unmistakable calls echoing across the still-snowy Blacktail Plateau. Western Meadowlarks, an icon of spring in the west as the state bird of both Montana and Wyoming, joined them in growing chorus the following week.

And the choir grows even more throughout April. Just as each day brings a few more minutes of daylight, so too do more bird species seemingly appear each new day in the park. After a few isolated sightings in February and March, Red-Tailed Hawks began showing up in droves throughout the first week in April, with other raptors (Peregrine Falcons and Osprey on 4/5, Turkey Vultures on 4/6, and Sharp-shinned Hawks on 4/9) in close pursuit. On April 18, there were 9 different duck species at Slough Creek including wigeons, gadwalls, and Yellowstone’s three types of teals. Many species, like the American Kestrels that showed up on March 18, are returning home to the territories where they were born. Others, like the brilliantly colored Wood Duck swimming around Blacktail Pond earlier this week, are just stopping by on their way to more northern breeding territories. And some of the migrations are actually departures. Many of the Golden Eagles that overwinter in Yellowstone, for example, migrate up to Canada and Alaska in the spring, though their departures are harder to record than the waves of new arrivals.

Osprey with brown trout

There are many reasons to pay attention to avian phenology. Birds are an indicator species, meaning that they are especially sensitive to environmental changes and provide an early gauge to assess the ecological ramifications of climate disruptions and natural or anthropogenic disasters. They are not only the first migratory animals to arrive in the park, they also must travel the furthest, in some cases migrating from Central and South America. This means that they must begin their migrations weeks in advance with no knowledge of the conditions in Yellowstone. Paying attention to when birds appear can help us assess how climate change is already affecting ecosystems across the hemisphere, as well as the integrity of migration corridors and the health of these cosmopolitan populations.

But the truth is that I would pay attention regardless. Finding your first bluebird of the year is like meeting an old friend you haven’t seen for a while. It brings joy, encourages observation, and makes familiar landscapes new again. This past week I saw my first Harlequin Ducks, Yellow Warblers, Lesser Yellowlegs, Northern Shovelers, Yellow-headed Blackbirds, Redheads, and Eared Grebes. I have yet to see a Western Tanager, but I’m looking forward to it.

Cover Image: Harlequin Duck, LeHardy Rapids

All images by YF / Matt Ludin

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Based out of the iconic Lamar Buffalo Ranch in the heart of Lamar Valley or the Mammoth Hot Springs Hotel, these multi-day programs offer an insider’s look into the world of Yellowstone’s remarkable wolves. Plus, you’ll have the opportunity to see all the wild animals that Yellowstone is famous for including bison, elk, moose, fox, and more. As past participants will attest, these one-of-a-kind experiences will leave you with memories to last of a lifetime.

See below for full details and dates for each program. We hope you consider joining us this winter in Yellowstone!

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In mid-February, Yellowstone Forever members funded the articulation of Wolf 302M. Expert articulator Lee Post flew in from Alaska to spend a week in Gardiner leading the project. Skeleton articulation, or “bone building” as Lee calls it, is the process of converting a dead animal into a completely cleaned and articulated skeleton (like the skeletons you see in museums).

Lee’s work on the bones of Wolf 302M is especially meaningful since the animal’s lineage is likely traceable to wolves reintroduced in Yellowstone through the Yellowstone Wolf Project. Born in 2000, Wolf 302 spent many years in the northern range of Yellowstone, mating, defending, and providing food for his pack. He was often referred to as “Casanova” because he mated with many females whereas most wolves are monogamous. He also spent a lot of time near roads making him more visible to park visitors.

When he reached the age of eight and a half, he finally became Alpha of a pack and was beloved by park visitors until his death in 2009. The articulation team’s first few days of work included sorting the skeletal remains of Wolf 302M and identifying what bones go where—a task made a bit easier thanks to meticulous drawings from Lee.

Every day, from sunup to sundown (and often after hours), Lee and the team came into our building just north of Yellowstone to work on preparing this important skeleton.

They connected the bones using a host of materials including epoxy, glue, pins, and wires. Lee explained that skeleton articulation traditionally involves mostly “seen” wires, but his goal is to have most everything unseen to ensure you can really get a feel for the skeleton as it was. The team also discovered plenty of interesting facts about 302M along the way, including many injuries from twisted ribs and broken vertebrae—evidence of epic battles likely fought for food or survival.

The skeleton will eventually head to the Heritage and Research Center as the team works on finding a home for it to live as an educational tool.

With the assistance from members of the Yellowstone Wolf Project and staff from the Heritage and Research Center, Lee was able to bring us insights into the life and journey of Wolf 302M—important information to help educate future generations and improve future conservation efforts.

Wolf 302 articulated be Lee Post and members of the Yellowstone Wolf Project and staff from the Heritage and Research Center.

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