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    National Park Montana

Tara Carolin's Science in the Crown Blog


Mating ball of garter snakes

NPS Photo by Melissa Sladek

Guest contributor: Melissa Sladek
Spring - Green Leaves and Sun and Breeding Snake Balls
May 20, 2011

A snake is a snake is a snake, especially the widely spread and well-known garter snake. But a massive ball of garter snakes entwined and slithering is another story.

A few years ago I took my daily noon walk along the Middle Fork River on the boundary of Glacier National Park. I remember it being an extraordinary spring day, temperatures rising into the low 60s and the sunshine pouring down, heating up my white winterized flesh. As I strolled down the path, I heard a large commotion in the brush toward the steep hillside to my left. The thrashing noise seemed to indicate a large bird or mammal making its way through the tangle of tree roots, rotting logs and last year’s fallen leaves. I stopped to look and waited. My eyes adjusted to the drab grays and browns of early spring vegetation. Nothing, I moved on. Advancing a few steps more, the rustling continued, but with an increasing slithering quality that sent shivers up my spine.

This time I stopped, paid full attention and waited. I saw movement. Leaves began to crunch and the critter making all of this noise finally came into view. At first I let out a gasp, followed by a small step back. The critter was actually a group of critters, one large writhing ball of garter snakes thrashing about. Suddenly one snake peeled off and then another and another. The oncoming snakes moved my previously bound feet and I leaped out of the way, letting them cross the trail. I quickly left the area to find new recruits to show this astonishing phenomenon.

Later I found that garter snakes often form mating balls in the early spring after arriving from their winter dens. We have two garter snakes in Glacier National Park, the terrestrial garter snake (Thamnophis elegans) and the common garter snake (Thamnophis sirtalis). T. elegans is found in mountainous terrain and is able to live at higher elevations, but is also found in low-elevation valleys. It overwinters in rocky areas, either alone or communally with other snakes. In late April/early May, the snakes emerge from their dens to heat up and to mate. Males usually slide out first, anticipating the arrival of the first female. As soon as the females come out from their dens, the males smell a sex-specific pheromone, creating a rapid frenzy of activity. Up to 25 males will converge on a female in hopes of mating with her, hence the “ball of snakes.”

After the mating is completed, the snakes peel off one by one. The female slithers off in search of food and eventually, to give birth to 3 to 27 live young.

Each spring I make my way down the same river trail, in hopes of seeing my “ball of snakes.” It is a walk of vigilance…each day lost is a missed opportunity.

This year my excitement at seeing the snakes remains, even if my vigilance does not. At eight months pregnant, I am slower than the unheated snakes. I try to get out to the trail each sunny day to look for my clear sign of spring...writhing snakes. Last week I was rewarded. I did not see as large of a ball of breeding snakes as in the past, but I did see one. And I was ready, with pictures and video to prove it.

Maybe I missed the biggest breeding ball event of the spring this year, but I have my own ball of joy writhing around and I am certain this will be one event I surely won't miss, vigilant or not.


John Waller in the field

John Waller prepares to tranquilize a grizzly bear.

NPS Photo

Guest contributor: Melissa Sladek
Just Another Day at the Office
January 24, 2011

In an interview with Wildlife Biologist John Waller, I discovered the highlights and intricacies of being a wildlife biologist in Glacier National Park. Waller is a National Park Service employee who manages a large spectrum of wildlife in the park, but his particular area of interest and study is large carnivores.

I interviewed John to learn more about his job. What I found was someone with amazing stories and experiences and a passion for what he does. Take a moment to read about John and his role as a wildlife biologist in Glacier National Park.

Melissa: I image you get to see and experience a lot of amazing things as a wildlife biologist at Glacier National Park. Can you describe one of your favorite days working here in Glacier and why it remains so memorable?

John: Yes. Glacier is a truly amazing place and every day brings a new adventure. I’ve had so many memorable experiences it’s hard to pick just one. When I think back on my experiences a kaleidoscope of images circle around – I see grizzly bears walking in and out of clouds at 50 Mountain, a young bull elk chasing Canada geese around the shore of a pond near East Glacier, a pack of howling wolves in Coal Cr. making my horse snort like a hippo, bighorn rams crashing their heads together with the sound echoing through the canyons, and shafts of sunlight filtering down through ancient forests. I really can’t just pick one.

Melissa: One of things I think would be most challenging in the field of wildlife biology is coming up with new and innovative research methods that provide you with accurate data, but are feasible with large roaming animals over large areas of land. How does your team work together to create the methods you use?

John: I work with a large group of peers – from other employees, agency scientists, and academics. We work together to develop and test new methods to see what works and what doesn’t. Sometimes we take the lead and other times we just assist. For example, Kate Kendall was a pioneer in using DNA collected from bear hair to estimate their numbers. I helped as I could operationally and learned from her research. Now, I’m employing that methodology to attempt to estimate the number of wolverines in the park. In collaboration with the US Forest Service, we’ve developed a unique method to acquire wolverine hair.

Melissa: What types of education and experience does someone who is interested in entering this field need to have?

John: It depends what your goals are. If you desire to work in a technical capacity, a bachelor’s degree in Wildlife Biology or closely related subject is usually required. On the other hand, if you want to pursue wildlife management or research in a professional capacity, at least a master’s degree is required. Experience can substitute for education, but wildlife is one of the most competitive fields there is, so the more of both you have, the better your chances. I typically have over a hundred applicants for every biotech position I advertise. Take advantage of every opportunity to gain experience. Most people usually start out volunteering for projects, then working into paid positions.

Melissa: From the smell of rotting carcasses to unwarranted wildlife deaths, I’m sure there are aspects of your job that aren’t too glamorous. What is your least favorite part of your job?

John: I would rather cut up a rotting carcass for bear bait than deal with a thorny personnel issue. I think in any job, personnel issues are the least favorite thing. As a project manager, there are lots of unglamorous administrative tasks that don’t seem to contribute to our mission but are required nonetheless. There are also days when you’re out in weather that makes you question your career choice. Rain, subzero cold, and relentless wind can take their toll.

Melissa: It seems that when people think of wildlife biologists, they think of researchers who are working closely with animals. How often does your research bring you up close and personal with the subjects you are studying?

John: I have been fortunate to have been involved in research and management projects that require close association with wildlife. Following and studying wildlife teaches you a lot about their behavior and habits. This knowledge is invaluable when you have to deal with wildlife in management settings because it allows you to better understand the circumstances that led to the conflict or problem. There have also been projects that haven’t required this. They are both valuable – just different.

Melissa: Could you highlight a few of the current research/management projects that you and your staff are working on?

John: We have a lot happening. This winter we’re trying to get a first-ever population estimate for wolverines in the park. This is a big effort but we’ve been very fortunate to have the help of lots of dedicated volunteers. It wouldn’t be possible without their help. We also have projects on harlequin ducks, bighorn sheep, mountain goats, grizzly bears and bats. Bats are a hot issue now because the white-nose fungus is sweeping westward and killing bats by the millions. Our most common species, the little brown bat, was just petitioned for emergency listing under the endangered species act. We know almost nothing about bats in Glacier so we’re trying to catch up now.

Melissa: Can you explain the difference between wildlife research and wildlife management? In which category would you describe your primary work in Glacier?

John: Wildlife research involves trying to acquire new knowledge about wildlife, be it understanding what they eat, how they move, disperse, reproduce, or how they are impacted by human activities. Wildlife management often entails using the knowledge gained through research. It may entail working to resolve human/wildlife conflict situations, implementing actions to mitigate for the impact of human activities, or developing planning documents that take wildlife needs into account. My work in Glacier is primarily management. Most of our research is conducted through collaborating agencies and universities. I maintain faculty affiliate status at University of Montana to help facilitate research in Glacier.

Melissa: In your years as a wildlife biologist, in Glacier and elsewhere, how do you think you’ve made the biggest impact? In other words, what do you believe your greatest on the ground accomplishment has been?

John: Professionally, I think my greatest accomplishment was completing a 10-year study of grizzly bear ecology in the South Fork Flathead River basin. The results of this study fundamentally altered land management throughout the west and contributed substantially to the recovery of the grizzly bear in this ecosystem. I have had other projects, but I think this one has had the greatest positive impact for wildlife.


Recorders of Glacier's revegetation and plant monitoring crews look on as Eric Schmidt cages a whitebark pine cone.

NPS Photo by Melissa Sladek

Guest Contributor: Melissa Sladek
Hardy Survivors of the Alpine
November 23, 2010

Much has been written about whitebark pine trees and their decline throughout the West in recent years. As a keystone species of the upper subalpine, whitebark pine plays a pivotal role within the ecosytem. Its disappearance is cause for major concern.

Typically, I hear researchers explain the importance of its seeds as a food source for grizzly bears and other wildlife, especially in the Greater Yellowstone area. And, at one time, before so many whitebark pines died, these seeds were also an important food source to bears in Glacier and the surrounding area.

The demise of this tree made me begin to wonder, "What other roles does whitebark pine play in Glacier and what might we expect to lose if it disappeared?"

Read the full "Hardy Survivors of the Alpine" article

Did You Know?

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Did you know that in 2010, the same year as our 100th anniversary, visitation to the park set a new record of 2.2 million visitors?