Once upon a time, there were tens of millions of bison on the North American continent. Today, there are somewhere between 400,000 and 500,000. Most are in commercial herds, with a relative few in private herds and on public lands.

Should there be more bison on the continent? There potentially is space for them on places like the 550,000-acre Thunder Basin National Grassland in Wyoming, the nearly 600,000-acre Buffalo Gap National Grassland in South Dakota, and the roughly 440,000-acre Comanche National Grassland in Colorado, just to name three locations.

And a new study out this past week explains why bison are more beneficial for grasslands than traditional livestock, and the benefits increase as herd size does. To understand what’s going on, we’re joined today by Professor William Hamilton from Washington and Lee University in Virginia, one of the study's co-authors.

It’s been said that the night skies are the other half of the National Park System. And it only makes sense, for when you’re in a park and the sun goes down you tend to look into the night sky to spot constellations or, if you’re lucky enough and in the right place, a comet overhead.

Keeping that other half of the park system in mind, today’s podcast will be a somewhat dark one. Our guest is Jeff Pfaller, a fine arts photographer who spent five years capturing night skies over national parks and other public lands.

A book coming out in October by Pfaller showcases synchronous fireflies at Great Smoky Mountains National Park, the famous illumination that makes Horsetail Fall in Yosemite National Park look like a cascading stream of lava, a shot of the whirling Milky Way against a colorful stump of petrified wood at Petrified Forest National Park, and many other nighttime images that remind us of that other half of the park system is overhead.

National Parks Traveler readers can obtain a $15 discount on the book's purchase price by using this link to order it.

Vessel-whale collisions are a significant concern in Glacier Bay National Park and Preserve, where nutrient-rich waters support a seasonal influx of humpback whales and other marine mammals. As one of the most visited marine parks in Alaska, Glacier Bay sees a high volume of vessel traffic, including cruise ships, tour boats, and private craft.

This summer an adult humpback whale was seen with a fresh, one-foot gash behind its dorsal fin which appeared to be from contact with a boat propeller.  This week the Traveler’s Lynn Riddick reaches out to biologist Chris Gabriele to discuss this incident and the park’s strategies to reduce whale collisions, including monitoring whale activity, warning systems, and public education. 

Is nature nonpartisan? Earlier this year we had an interview with Dr. Caleb Scoville from Tufts University, who received an Andrew Carnegie fellowship to explore whether environmental issues are highly partisan.

It can certainly seem that here in America just about everything is partisan these days, but is nature partisan? 

As another of our guests pointed out, those who enjoy going out into nature come in all political flavors. That said, our guest today is Benji Backer, the driver behind the Nature is Nonpartisan campaign to get the American public – all of us – to convince the decision makers in Washington that the environment is too important to be a partisan issue.

El Camino Real de Los Tejas is a network of trails that connected Spanish missions, settlements, and military outposts from Mexico through Texas and into Louisiana. Now a national historic trail, this road played a crucial role in the Spanish colonization of the region in the late 1600s. It served as a vital route for communication, trade, and military movement. 

Over time, that trail facilitated cultural exchange and interaction between Spanish settlers, indigenous peoples, and later, Anglo-American pioneers. The 2500 mile route is marked by numerous historical sites, including mission ruins, forts, and early settlements. It provides a tangible link to the colonial past and the diverse communities that shaped Texas and the broader Southwest. 

The Traveler’s Lynn Riddick takes a stroll along the trail with expert Steven Gonzales, who shares his knowledge about the significance of the trail and the American historical narrative. 

The National Parks Conservation Association is almost as old as the National Park Service. The Service, as you probably know, was established in 1916, and NPCA came along three years later.

Through the 106-year history of NPCA, there has been only one woman who held the title of president and Chief Executive Officer. That woman is Theresa Pierno, who has worked for the park advocacy group for more than two decades, and as NPCA’s CEO and president for the past ten years.

At the end of this year Theresa will step down from the organization, but she won’t stop advocating for the parks. Theresa is our guest today, and will both look back on her tenure with NPCA and the current political climate that is threatening the National Park Service and the national parks.

Grizzly bears. They define charismatic megafauna. Huge animals that draw both human admiration and fear. Once they roamed the entire country, though that was a long time ago. Today there are pockets of grizzly bear populations in the Rocky Mountains from Yellowstone to Glacier National Parks.

Among the questions that revolve around grizzly bears is how many are too many, are they a threat to humans, should they be removed from the landscape, or protected?

To explore those issues our guests today are Erin Edge and Joseph Vaile from Defenders of Wildlife, a nonprofit wildlife advocacy organization.

Running nearly 2,200 miles along the spine of the Appalachian Range from Georgia to Maine, the Appalachian National Scenic Trail arguably is the world's most famous long-distance trail.

Some think it's also one that can be very crowded in spots. Morgan Sommerville, the director of visitor use management for the Appalachian Trail Conservancy, joins us today to discuss the trail in general and whether it's too crowded.

Heading into the National Park System this summer? Going it alone, or have you booked a tour company? What do you think about how the Trump Administration and Congress are treating the National Parks and the National Park Service? Have you reported any park signs to Interior Secretary Doug Burgum that disparage Americans, dead or alive?

As you can tell there’s a lot going on in the parks. Some good, some not so good, and some downright bad. It’s a lot to digest, and a lot to discuss.  To help us gauge a sense of what’s going on out there, our guest is Leigh Barnes, President of the Americas at Intrepid Travel, an Australian-based tour company that has been leading trips around the world since 1989. Part of their cache is keeping tour groups small, a dozen or so travelers along with the guides.

The company also recently conducted a survey of Americans to get their sense of how politicians are treating the Parks and the Park Service that we’ll discuss with Leigh.

Anniversaries and birthdays give us time to reflect on individuals, accomplishments, and moments in history. They often refresh our memories and can serve as motivators to do something.

This year marks the 100th anniversary of the Appalachian Trail Conservancy, which was established in 1925, just two years after the first sections of the Appalachian Trail opened.

To discuss the trail, some of its history, and the challenges it faces today, our guests are Sandi Marra, CEO of the Conservancy, and Brendan Mysliwiec, the Conservancy’s Director of Federal Policy.