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We make podcasts and newsletters that connect people with the cities they love.

City Cast Denver

Let us help you find Mother Nature in this concrete jungle.

For centuries, beavers have been seen as little more than a nuisance to farmers and ranchers, with their dams causing flooding and unwanted changes to local vegetation. But in recent years, wildlife experts have begun trying to raise awareness about the critical role that beavers actually play in the local ecosystem. Earlier this summer, the Pitkin County Healthy Rivers program kicked off new research on Colorado beaver populations in an effort to restore the animal to areas where they’ve been eradicated. County officials have also launched this 

 to teach landowners how to peacefully coexist with the critters.

Here are just some of the ecological benefits that beavers have on their surrounding habitats:

Beavers typically prefer slow-moving streams surrounded by willows, aspens, cottonwoods, and alders for food and building materials.

In the wild, beavers tend to live up to 10-12 years and grow to weigh anywhere from 35-65 pounds.

Beavers are herbivores, eating bark, leaves, and aquatic vegetation.

Beavers’ teeth are as strong as metal and never stop growing (they can grow up to 4 feet per year!). A thick coating of iron makes their teeth appear orange.

Contrary to popular belief, beavers don’t use their tails to pat down mud. Rather, beavers use their long, flat tails as rudders while swimming in the water, a prop for balancing when carrying large loads of sticks, and to slap the water in communication with other beavers.

Beavers are monogamous. They live and work in family colonies of 2-12 members.

For centuries, beavers have been seen as little more than a nuisance to farmers and ranchers, with their dams causing flooding and unwanted changes to local vegetation. But in recent years, wildlife experts have begun trying to raise awareness about the critical role that beavers actually play in the local ecosystem. 

Why Colorado Needs Its Beavers

Urban Almanac

Right now, Colorado — more specifically, the 

 Colorado town of La Junta — is smack dab in the middle of tarantula mating season, and 

. Despite often being called Colorado’s great annual “tarantula migration,” these little critters aren’t actually 

 anywhere. Rather, thousands of sexually mature male tarantulas leave their burrows for an elaborate mating ritual that includes them “knocking” at female tarantulas’ burrows looking for love, and often ends in the males being eaten by the females. Tarantula mating season typically lasts from late August through early October, with a peak in mid-September.

The Denver Butterfly Pavilion conducts its own in-depth 

tarantula breeding, conservation, and education efforts

” exhibit. Step into the 80-foot “Spider Zone” enclosure to get up-close and personal with dozens of free-roaming spiders representing species from more than 20 different countries!

Right now, Colorado — more specifically, the southeastern Colorado town of La Junta — is smack dab in the middle of tarantula mating season, and it’s quite the spectacle.

What is the Colorado Tarantula 'Mate-gration'?

On Sept. 1, Rocky Mountain National Park officials instituted the 

annual closure of certain wilderness areas

 within the park as elk rut begins. These majestic mountain animals will start to descend from higher elevations to post up around the trails, rivers, and golf courses of nearby mountain towns. It’s a popular reason for making the quick drive up to RMNP for elk-spotting, but it’s really important to do so respectfully and responsibly, while giving the animals their space. Here are a few things you should know:

! It typically starts mid-September and lasts through mid-October.

It’s a Great Opportunity for Elk-Spotting

If you’re hoping to catch a glimpse of these animals up-close, it won’t be hard. Most famously, they tend to hang around Estes Park this time of year — often right in the middle of town! (Estes even hosts an annual 

Elk rut is a super cool thing to witness, especially when you get to 

. But it’s critical to remember that the bull elk are super territorial this time of year, and you should 

 (now or ever!). Also, make sure your dog is on a leash — Fido 

 want to get between two bull elk defending their herds. And just a reminder: elk calling in the park is prohibited.

🦌 Learn More About Elk Rut

Elk  will start to descend from higher elevations to post up around the trails, rivers, and golf courses of nearby mountain towns. It’s a popular reason for making the quick drive up to RMNP for elk-spotting, but it’s really important to do so respectfully and responsibly, while giving the animals their space. Here are a few things you should know:

It's Elk Rut Season in the Rocky Mountains

 of emerald ash borers on Colorado’s Western Slope. This invasive wood-boring beetle native to East Asia feeds under the bark of ash trees, cutting off the flow of water and nutrients, causing a slow and gradual death for the tree. The beetle was first found in Colorado 10 years ago in Boulder; 

 “the most destructive and economically costly forest insect to ever invade North America.”

Colorado State University reports that roughly 15% of the state’s trees are ash, with nearly 1.5 million providing shade to metro Denverites. Over the last decade, the beetle has largely taken root in ash trees across north Denver, from Fort Collins to Longmont and Thornton to Arvada. Most recently, an infestation was confirmed in Littleton.

If your ash tree is infested with these pesky little beetles it may exhibit some of these symptoms:

Sparse leaves or branches in the upper part of the tree

Vertical splits in bark possibly showing S-shaped “tunnels” underneath

Miniature leaves at the tips of branches late in the summer

Prevention, Mitigation, and Eradication Measures

A tree can be infested long before it begins to show signs of a health decline — treat your tree before you even suspect an infestation

 should be applied every 2-3 years for the life of the ash tree

For a more holistic approach, some municipalities have strategically deployed tiny, stingless wasps to attack the beetles’ larvae. Woodpeckers also feast on borer larvae.

Never transport raw ash wood (often firewood) — the most effective way emerald ash borers spread is by hitching a ride on wood transported by humans

🪲 Learn More

In June, officials confirmed the first appearance of emerald ash borers on Colorado’s Western Slope. 

Beware the Emerald Ash Borer

Nothing reminds me of Colorado’s cowtown roots quite like a field of rolling tumbleweeds on a windy summer day. You can expect to see more and more of these thistly balls of dried up brambles this time of year as temperatures drop and shrubbery begins to die for the season. 

Tumbleweeds can be formed by a number of shrub-like plants, but most commonly they begin their lives as Russian thistle, a non-native invasive species thought to have hitched a ride to the U.S. from overseas back in the late 1800s. In the fall and winter, these thistle bushes dry up, die, detach from their root systems, and spend the rest of their existence blowing aimlessly across open fields, pinned under cars, and otherwise being moderately annoying.

Though mule deer, prairie dogs, cattle, and other local animals feed on Russian thistle, once they transform into a tumbleweed, they’re not so harmless. One of the biggest hazards tumbleweeds pose is fire risk (I mean, they’re basically quick-moving tinderboxes on a windy day!). Too many of them can cause roadblocks (see 

 in the image above 👆) or clog irrigation canals. And thanks to their ever-mobile nature, it’s almost impossible to reign in their spread.

Experts advise that the best way to take control of tumbleweeds is to (literally) nip Russian thistle shrubs in the bud!

🌵 For more on tumbleweeds, see my sources: 

It's Tumbleweed Season! 

Black bears are on our minds lately. Peyton Garcia recently told you the story of 

, an original inhabitant of what is now the Denver Zoo. And last week, black bear “Hank the Tank” was relocated from California to the Wildlife Animal Sanctuary after 

having broken into too many houses to look for snacks

. Let’s take a closer look at the hungry giants.

Some, like Hank the Tank, are a dusty brown. There’s even a black bear species in the British Columbia Archipelago with white fur. Their habitat extends from the northern tip of Canada and Alaska to northern parts of Mexico, and can live in both coniferous and deciduous forests.

Like most hungry creatures, black bears will go to great lengths to find their next meal. They’ll also keep coming back to places where they’ve found food before, so take special precautions when you’re visiting the foothills, camping, or hiking. Colorado Parks & Wildlife has a great video about 

The best strategy for keeping bears away is to minimize anything that might entice them. Here are a few tips:

Don’t feed them! Seriously, even if you’re thinking about throwing food from a distance or leaving it out, don't do it.

Clean off food residue and leftovers after grilling. You may not have invited them to the BBQ, but they’ll come anyway.

Don’t leave food in your car when parked near a campground or hiking trail.

All About Black Bears

 to the Colorado wilderness. The once native “mountain devil” has been unseen in Colorado since 2009. The idea of reintroducing the species to the area has been floating around for more than a decade, but hesitation around its federal conservation status has hindered wildlife officials from taking action. Now, the U.S. Fish and Wildlife Service is set to vote on whether the species should be protected under the Endangered Species Act.

Though they were once native to the region, wolverines were nearly wiped out completely from the lower 48 states in the early 1900s. Experts believe there are currently only about 300 wolverines across the country, most of them living in Montana. However, it’s due to robust populations in the thousands in Canada and Alaska that the species hasn’t been listed as endangered yet.

Wolverines are a type of weasel that look like a cross between a small bear and a badger. They are known for being able to 

, feeding on already dead animals, but will kill rabbits, rodents, and even livestock.

“skunk bears” or “mountain devils”

. Sadly, experts believe wolverines will lose 30% of their habitat in the lower U.S. over the next 30 years due to climate change.

The last wolverine seen in Colorado was spotted in 2009, but before that, one 

 that are typically only spotted together for mating purposes.

🔎 Learn More About Wolverine Reintroduction Plans

State officials are considering bringing wolverines back to the Colorado wilderness. The once native “mountain devil” has been unseen in Colorado since 2009.

Is It Time to Bring Wolverines Back to Colorado?

You’ve probably heard of “murder hornets.” They’ve taken the internet by storm since they were first spotted in the U.S. in 2019. But there are a few things you’ve probably gotten wrong about these hornets, and bug scientists want to set the record straight.

. They were previously known as the Asian Giant Hornet (or “murder hornets” by the public and the media). But in an effort to avoid anti-Asian sentiments, the Entomological Society of America officially 

Also, despite their intensely painful stings that can 

. (Yay! 🙏) But they do murder honeybees. (Boo 👎)

 If you, like me, thought you saw one fly into your campsite recently, you were wrong. According to the Colorado Department of Agriculture, the Northern Giant Hornet can’t survive in our dry climate. Instead, we’re most likely 

, which is native to Colorado and is a rather helpful type of wasp. They tend to show ambivalence toward humans and help us eradicate peskier pests like locusts and cicadas.

🔎 Cicada Killer Wasps vs. Northern Giant Hornets

You’ve probably heard of “murder hornets.” They’ve taken the internet by storm since they were first spotted in the U.S. in 2019. But there are a few things you’ve probably gotten wrong about these hornets, and bug scientists want to set the record straight

Here's Why You Don't Need to Worry About 'Murder Hornets' in Denver

Here's Why You Don't Need to Worry About 'Murder Hornets'

A second troll is coming to Colorado. The first — the infamous, 15-foot 

 — lives in Breckenridge. You can find him watching over hikers strolling along the Trollstigen Trail. Isak is known to be quiet but friendly, always willing to indulge selfie-takers, but doesn’t take kindly to being climbed on. He serves his community by showing visitors the benefits of recycling (he is, after all, made entirely of reclaimed wood). Your best chance for catching Isak on his own is before 10 a.m. or after 5 p.m.

Soon though, Isak will have a fellow troll friend not too far away. The 

new troll is expected to take up residency

 somewhere in Teller County, a few hours south of Denver, and arrive sometime between July 27 and August 4. Like Isak, the Teller County troll is coming to us from the troll king himself, Danish artist and activist Thomas Dambo — and it’s not the only one! Dambo is in the middle of a cross-country journey during which he will introduce 10 new trolls, each with their own unique personality, to forests and parks across the U.S. You can keep your eye out for updates on the Teller County troll — and its brethren in other states! — by following 

👀 Plan a Troll-Sighting Trip!

A second troll is coming to Colorado. The first — the infamous, 15-foot Isak Heartstone — lives in Breckenridge.

There's a 2nd Troll Coming to Colorado's Wilderness

There's a Second Troll Coming to Colorado's Wilderness

Big news for the local bug-loving community: Last month, the Butterfly Pavilion saw the emergence of its very first lab-bred adult fireflies as part of its 

, an initiative born in 2019 dedicated to breeding native Colorado fireflies in order to learn more about their life cycles and sustainability needs.

Yes! They can be found in small populations along the Front Range from Greeley to Pueblo. They require wet habitats and can be seen lighting up the evening sky for a few short weeks in June and July (mating season).

The team at BP took notes about the kind of environmental factors — from diet to shelter to temperature — that will best help this species thrive. Fireflies serve as an indicator species for wetland habitats; their health directly indicates the overall health of their surrounding ecosystem.

BP will continue to study this species and other fireflies native to Colorado with the goal of breeding a sustainable population in the lab as part of conservation efforts — and you can help! The next time you see fireflies, report the sighting to the 

If you know where to look, you can spot the little lightning bugs in Fort Collins, Loveland, Boulder, and even Littleton! Check out 

Fireflies are not flies at all, but beetles!

Once they reach adulthood, they only live for a few weeks

Each firefly species has its own distinct flashing “language”

The females of some species are known to flash patterns of other species to attract those males, which they then kill and eat

Big news for the local bug-loving community: Last month, the Butterfly Pavilion saw the emergence of its very first lab-bred adult fireflies as part of its Firefly Lifecycle Project, an initiative born in 2019 dedicated to breeding native Colorado fireflies in order to learn more about their life cycles and sustainability needs.