The Natural Laboratory is a series of podcasts exploring science in Point Reyes National Seashore. This series is produced by Point Reyes National Seashore Association in collaboration with the National Park Service and the Pacific Coast Science and Learning Center.
The Natural Laboratory: How Wildlife Withstand Wildfires
Jerimiah Oetting [outside]: Alright, so...what are we doing?
[about three people laugh as gravel crunches underfoot as they walk]
Taylor Ellis [outside]: Yeah, we're hiking into an area of the Woodward Fire.
JRO [in studio]: That's Taylor Ellis. He's a field biologist with Point Reyes National Seashore. We're hiking along the Bear Valley Trail, where the Woodward Fire burned last summer. I should mention that, as of mid-January , this area is closed to visitors. For good reason: crews are still working hard to make the roads and trails safe.
[gravel crunches underfoot]
TE [outside]: Uh, and, we want to see if we can get an owl detection today. Uh, we're kind of curious if the owl is still using its core area after the fire.
JRO [in studio]: This isn't the typical time to monitor spotted owls in the park. We were hiking in December. It's usually easier to spot the owls during their breeding season, between March and July.
TE [outside]: But we're still gonna go and check some of the known haunts they have and, uh, see if we can find them.
[Taylor mimics spotted owl hooting call out in the woods]
JRO [in studio]: Taylor is hooting for the owls to see if any reveal themselves to us. Six different spotted owl territories were impacted by the fire. Taylor says he hasn't visited all six yet to see how they were affected.
TE [outside]: The ones that I have seen, it looks like it didn't burn very hot in those areas, so most of the big older trees are there, which is important for spotted owls.
JRO [in studio]: This is prime spotted owl habitat, he says. An area with tall Douglas fir trees, some that are hundreds of years old.
Black fire scars stretch up the boles of some of the trees. But the burn was patchy. On one side of the trail, there were charred clumps of sword fern. But then, just uphill, bright green ferns appeared to be completely untouched. This area seemed a good example of a fire that might actually help spotted owls.
TE [outside]: It's not that any fire is good, but, sort of, a low-level fire that doesn't get too hot, which is what they would mostly be if they happened more often.
JRO [in studio]: In the last episode, we talked about how some plants in the park actually depend on fire. But what about wildlife? Plants aren't the only things impacted by fire, and that means the critters that call Point Reyes home are also adapted to recover.
There are a ton of animals here. Almost half of North America's bird species have been spotted in the park. There are mammals, fish, amphibians, reptiles, and thousands of invertebrates. Over 50 of these species are considered rare, threatened, or endangered.
With all the other forces that threaten their existence, how do these animals continue to persist after a fire?
On the podcast today: how wildlife coexists with wildfires. Spotted owls, red-legged frogs, steelhead trout—they're just a few examples of animals you may have heard of that could be impacted by fire. But there's another animal—one you might not even know about, that's unique to Point Reyes. A living fossil—elusive, hidden and all around peculiar. It could be lurking just feet away from a trail and you'd never know.
All this and more, stay tuned….
JRO [in studio]: This is the Natural Laboratory, from Point Reyes National Seashore. I'm Jerimiah Oetting.
[gravel crunches underfoot]
TE [outside]: We just have a really high density of spotted owls in Marin County, um, compared to other parts of their range.
JRO [in studio]: Marin County is one of the last refuges for the northern spotted owl. Populations of the owl have dwindled across their range, which extends from just south of Point Reyes National Seashore all the way up towards British Columbia. The northern variety is one of three spotted owl subspecies. It prefers big old growth forests that have vanished over the last couple of centuries. A robust spotted owl population is a good sign of a healthy forest. Unfortunately, though, the owls are listed as threatened, at both the federal and state levels. What little habitat remains for northern spotted owls has been encroached upon by both humans, and by a close but unfriendly relative—its boisterous cousin, the barred owl.
Barred owls are invasive out West. They aggressively take over spotted owl habitat. Research shows that spotted owls require about four times the territory of barred owls. That means that barred owls can pack more densely into areas that would have once belonged to only a few spotted owls.
This is partially because barred owls eat almost anything. They gobble up many of the foods that spotted owls depend on—like woodrats, deer mice, voles, and flying squirrels—but also amphibians, fish, even other birds. They're bigger and burlier than spotted owls. And they're more aggressive. For spotted owls, that means less resources and less space. They get pushed to the edges of their habitat where they struggle to survive.
TE [outside]: And that's what's happened a lot in places like Olympic National Park and Redwood National Park, both north of us.
JRO [in studio]: But not in Marin County. The first barred owls appeared in Marin in 2002. Since then, they've had a steady presence in the area. But luckily for the spotted owl, they haven't completely taken over as they have elsewhere. Northern spotted owls in Marin County are doing better than pretty much everywhere else in their range.
TE [outside]: You know, I think that might be because there's a lot of food available to them in the form of all the wood rats that we have out here. We'll probably see some of their nests, at least in unburned areas of the forest.
JRO [in studio]: Those woodrat nests can burn up in a fire, removing a vital food source for spotted owls. But fire can also be good for the owls, clearing out shrubs and opening up the forest understory. A more open forest floor makes it easier for the owls to hunt.
TE [outside]: And then they also, of course, want some decent, kind of like, canopy cover, like a kind of closed canopy that they can sort of hide out in, you know, they can perch there, you know, hawks and stuff can't see them from above. And they can just kind of quietly sit there in the shade, um, and just wait for some prey to come along.
JRO [in studio]: For spotted owls, an open understory and a nice overstory is a great balance—one enabled by fire. But spotted owls are predators. And they can fly. For their rodent prey, escaping a fire is a bit of a challenge. And rodents are an important food source, not just for owls, but for animals like bobcats, foxes, and coyotes.
TE [outside]: You might lose some wood rats in the actual fire event, but, you know, they are rodents. They will be back from surrounding areas.
JRO [in studio]: Other terrestrial animals are sensitive to fire, too. California red-legged frogs live in the park. Like the spotted owl, red-legged frogs are federally protected, because they're a threatened species.
Dr. Patrick Kleeman is a research biologist with the USGS in Point Reyes. Most of his work focuses on conserving endangered amphibians.
PK [in studio]: Luckily, our amphibians, locally, don't seem be greatly impacted by wildfire. Of course, any amphibians that are in a terrestrial situation away from a pond are probably going to get burned up. So, it's definitely going to affect individuals, but doesn't seem to greatly affect the actual populations.
JRO [in studio]: Dr. Kleeman says after the Vision Fire 25 years ago, scientists surveyed the breeding ponds known to be important for amphibians.
PK [in studio]: After the Vision Fire, they typically found the same amphibian assemblage at those ponds. And that's great news. And so, other things, like mountain beavers, is definitely a direct effect that can have consequential damage for years to come.
JRO [in studio]: Mountain beavers. Ever heard of them? Despite their name, they aren't a mountain variety of the bucktoothed tree chompers that you're probably thinking of. Nope. These are far stranger.
Seth Bunnell [outside]: Mountain beavers are coprophages. And they're, um, hosts to the world's largest flea. And they're also the only member, the only living species in an extinct family that was once widespread, and they're one of the most primitive rodents.
JRO [outside]: Cool. So, they eat their own poop. They have the largest...or they eat not their own poop, but like…
SB [outside]: Yeah, they eat their own poop.
JRO [outside]: Okay.
SB [outside]: They're very hungry because they live on salad. And they have to eat a lot. And to get the nutrients out...like a rabbit does the same thing. They sort…so they have two generations of droppings, and the first generation of droppings, they eat 'em again to get more nutrition.
JRO [in studio]: That's Seth Bunnell. He's a field biology extraordinaire. He knows a thing or two about mountain beavers. If you didn't catch it, not only do mountain beavers eat their own poop, but they're plagued by the world's largest flea, commonly known as the mountain beaver flea. The flea can be up to half an inch long.
Seth also mentioned that mountain beavers are the only living species in their genus, Aplodontia, and in their family. They're a living fossil—a relict [sic] of a group of animals that were once widespread eons ago.
But they're not just unique because of their strange behaviors and life histories. They look pretty weird, too.
SB [outside]: They have very small eyes, but I assume they can see some. They have very...a lot of whiskers. And they probably have a very good sense of smell. And, um, a lot of…they're very tactile. If you look at their whiskers, that's like a big ol' fan of whiskers. They can probably feel every side of their burrow and they can probably feel every plant around them, and they can probably feel, like, you would think, vibration really well.
And they have pretty well-developed looking ears although they're not as big like mouse ears but they're...they're funny ears. I mean, they've got strange ears.
They've got an unusual, kind of, shaped body and feet and ears...and eyes.
Unidentified voice [outside]: Yeah, they're a weird lookin' animal.
JRO [in studio]: Mountain Beavers are about two to three pounds and roughly a foot in length. They have a large skull compared to their body size. The few photos people have managed to capture of them, they look almost awkward, like they don't quite fit in. They're considered the most primitive living rodents, furry with long whiskers and black, beady eyes.
Further north, in the temperate rain forests of Oregon and Washington, mountain beavers are so common they're sometimes considered a backyard pest. But we have our own endemic subspecies here—the Point Reyes mountain beaver. It's unique to this area.
Point Reyes mountain beavers live at the southern edge of the mountain beaver's coastal range. The California Department of Fish and Wildlife lists it as a species of special concern, potentially vulnerable to extinction.
Scientists know little about the Point Reyes mountain beaver. But they do know its population is pretty small. And that the animals are highly vulnerable to fire.
Patrick Kleeman [in studio]: They can be severely impacted by fire because they really require, you know, a moist understory of vegetation.
JRO [in studio]: That's Dr. Patrick Kleeman, again, the research biologist at USGS in Point Reyes.
PK [in studio]: And they have these primitive kidneys, they can't concentrate urine. So, they're urinating all the time. So, they have to replace like a third of their body weight in water every day. And that typically comes from, you know, harvesting vegetation around them. If that gets burned away, there's just literally no way for them to survive.
JRO [in studio]: He says that mountain beavers don't move around much. If a fire comes or their habitat is burned away, they don't have much hope of survival.
PK [in studio]: But what was shown was they can also come back as the vegetation does get restored over time, but it takes time.
JRO [in studio]: A lot of what we know about the Point Reyes mountain beaver comes from work done by Dr. Gary Fellers, a park service biologist who retired in 2013. Unfortunately, Dr. Fellers recently passed away in 2019. Dr. Kleeman remembers Dr. Fellers as a force in field biology, pioneering research methods for studying wildlife. The two were close.
PK [in studio]: We, you know, just worked together and knew each other for a long time. He was a really excellent biologist, he was kind of an old-school biologist, he had very broad interests. And he's very, you know, observational and natural history oriented, but he also produced really good science.
JRO [in studio]: The 1995 Vision Fire cleared away big swaths of the shrubs mountain beavers love in the forest understory: poison oak, sword fern, coyote brush, and coffee berry. Dr. Fellers saw this as an opportunity to locate their burrows and assess how fire may have impacted the species.
What he observed didn't look good for mountain beavers. With 40% of their habitat destroyed within the burned area of the Vision Fire, Dr. Fellers estimated that at most, less than 2% of mountain beavers survived. That's for a fire that only burned for nine days.
Dr. Fellers noted in his study that mountain beavers lived alongside fire for hundreds, even thousands of years. But at the time of the Vision Fire, there had been a century of fire suppression at Point Reyes. The Vision Fire was unnaturally intense and destructive.
PK [in studio]: You know frequent spotty fires are different than intense fires that take out huge swaths of land that we're seeing these days across California. So, you know, the patchy nature of what fires used to probably be like, prior to white settlement, is probably, you know, the reason they could persist.
JRO [in studio]: Dr. Fellers estimated it would take between 15 and 20 years for mountain beaver populations to recover. This year marked the 25th anniversary of the Vision Fire. But very little monitoring for mountain beavers has occurred in the park since the era of Gary Fellers.
PK [in studio]: Just like everything, you know, monitoring of any animal takes time and money. And, you know, nobody's been putting that out there.
JRO [in studio]: Money is one issue. But looking for mountain beavers is also just hard. Unlike hooting for spotted owls and waiting for them to swoop into view, mountain beavers are nervous, elusive creatures. Relying on seeing them to try and assess their population wouldn't really work out.
Instead, scientists use their burrows as an indicator of their population. With support from Point Reyes National Seashore Association, park service biologists plan to reboot a mountain beaver monitoring program. They invited Seth Bunnell, who we heard from earlier, to provide training for park staff.
SB [outside]: We wanted to just, kind of, all learn together and get a good search image for, uh, spotting the burrows and other evidence, you know, tracking them.
JRO [in studio]: I joined Seth and park staff in the field for a training session. Taylor Ellis was also there, who you heard hooting earlier in the episode. And Matt Lau, a park service ecologist who usually works with snowy plovers.
Seth is kind of a jack of all trades field biologist. He was carrying this impressive shepherd's staff; it looked kind of like a five-foot-tall walking cane.
SB [outside]: It's from a basque shepherd back in the early 1940's.
JRO [outside]: Oh cool. And you take it with you when you're out in the field, like, no matter what you're doing? Or just for mountain beavers or other burrowing things?
SB [outside]: No, I usually bring my titanium field hook that I bought from a snake wrangling company.
JRO [in studio]: Seth was showing us how to identify mountain beaver burrows. Their burrows are about the diameter of a large grapefruit. Seth was using the shepherd's staff to probe the burrows to see how deep they went, which kind of helped him determine whether or not it was actually a burrow or just a hole dug by some other animal.
SB [outside]: See this is more like chipmunk diameter, or maybe this looks like a mouse.
JRO [in studio]: We first explored some of the areas where Dr. Fellers had found mountain beavers decades ago. But there were a ton of shrubs.
JRO [outside]: Well one thing's for sure, they really like to always locate their burrows in a thicket of poison oak.
SB [outside]: Yeah, that's the worst part of this. [someone chuckles]
JRO [in studio]: Spotting a burrow in the patchy light underneath that shrub canopy seemed next to impossible. We later moved into the footprint of the Woodward Fire in an area off the side of a road, where the shrub layer had burned up in the fire.
SB [outside]: I think these are mountain beavers.
JRO [outside]: Like, this one right here?
SB [outside]: So, here, like, I can light it up for you if you want to come in.
JRO [in studio]: There it was...a burrow. Honestly, it was kind of anticlimactic. A hole in the ground among many holes in the ground.
SB [outside]: But look. It looks like stuff has been moved inside. See that? All that particulate? And then I would look at that and see if there's any clues in it, you know, like, if it's vegetable ma…plant material.
JRO [in studio]: But for an animal as elusive as the mountain beaver, a hole in the ground is about as close as you get. I was told that these burrows are not likely occupied any longer. After all, we were in a recently burned area. We'll hope the burrows former occupant got wise and fled before it was too late.
Taylor told me they found a burrow or two elsewhere they thought were occupied. With a motion-activated wildlife camera setup outside the burrow, he said they hope they can score a photo. In the meantime, all of us were inspecting holes in the ground, seeing how much of our fists fit in before the burrow tapered off. That's part of how you identify if it's actually a mountain beaver burrow.
You know, before I started making podcasts, I was a field biologist too. I've worked on quite a few monitoring projects. And in all of those projects, I've occasionally been struck by the realization that, to a casual observer, all of this looks absolutely ridiculous. Grown adults, crawling around on the forest floor, shoving our hands into rodent burrows. I mean, why are we doing this? Why do we care about a population of primitive rodents?
It's not easy to fully grasp how these animals fit into their ecosystems. But Dr. Kleeman has some ideas.
PK [in studio]: I think it's interesting that they're just such an ancient animal. I mean, they've been here forever. [chuckles] And they still persist. They are prey for things like bobcats and coyotes, mountain lions, definitely larger owls. They're probably really good nutrient cyclers because they do all this burrowing underground, they're aerating underground, they're taking all this plant matter underground. They're basically fertilizing underground. They're so much a part of that ecosystem out there—that coastal scrub ecosystem—it's just we don't think about them that much because they're not seen that much.
JRO [in studio]: We share this planet with some strange creatures. As I watched this group of professional biologists on their hands and knees, puzzling over the vacant burrows of rodents, I realized: we're pretty strange ourselves. Who are we to judge?
Humans have only been on this planet for about 250,000 years. The mountain beaver has been around for at least 50 million years. Now, the Point Reyes subspecies might be threatened with extinction. For all of its time in Point Reyes, the mountain beaver has kept humbly to itself. Doing what it does. Apparently eating its own poop, urinating constantly, and waging battle against gigantor fleas. Mountain beavers might not inspire the awe of a swooping spotted owl, but you can bet that they play an important role at Point Reyes. And that, I think, is worth studying. And worth protecting.
JRO [in studio]: Thanks for listening to this episode of the Point Reyes Natural Laboratory podcast. My name is Jerimiah Oetting and this is my last episode with Point Reyes. I really enjoyed making all of these and I hope you enjoyed listening to them. It was a great experience.
As usual, thanks to all the scientists who gave me their time and made this episode possible. And for the support of the Point Reyes National Seashore Association and the National Park Service. My name is Jerimiah Oetting and thanks for listening.
Point Reyes is home to a great variety of animals. Half of North America's birds have been spotted in the park, not to mention its reptiles, amphibians, fish, and mammals. How do these creatures respond to a fire? In this episode, Jerimiah Oetting speaks to park scientists to learn how certain vulnerable species might be impacted by wildfires. Join us as we hoot for owls and track one of the more elusive and curious species in the park, the Point Reyes mountain beaver.