Winter weasel without snow

I finally got it:  I cam-trapped a weasel in its dashing white winter camo.

But as you’ve noticed, it’s sticking out like a sore thumb because there’s no snow 2 feet underground where the picture was taken.

I’ve wanted that photo since I learned that weasels are frequent but uninvited guests in mountain beaver tunnels.     

Wouldn’t it be cool to show a winter weasel without the benefit of its winter backdrop of snow?

How do you get that picture?

You can nature-fake it – just live trap a weasel (no small feat) and photograph it on soil and leaf litter set in a cage.

Or you can set a camera in a mountain beaver burrow.

But there’s risk and a technical challenge to leaving a camera underground in a rodent burrow for half a year.  

You have to supplement the camera’s normal battery power so it can take flash photos for 6 months. (I wired 4 external batteries -- 2 D and 2 C cells -- to the camera for back up power, and used 2 9-volt batteries to power the controller.)

And you have to retrieve your camera before spring snowmelt floods the burrow and drowns the camera or buries it in silt.

I was ready to deploy in the fall of 2013, but procrastinated, and the snow shut me out that winter.  

I procrastinated again in 2014, but it was a drought year, and I got away with setting the camera in early November.

Disappointment came the following May when I discovered the batteries died 45 days into the bargain and before any weasel made an appearance.  Murphy’s Law.  

Last winter I had the camera in the ground on October 7^th. 

The camera had been out 8 months when I drove to the site a couple weeks ago with Bill and Diane Wilson. 

Our timing seemed okay. The snow was gone at 6000 feet, and the Forest Service road was dry.  The only thing that was worrisome was the Yuba River, which was already roaring from snowmelt.

At 7000 feet snowdrifts blocked the road.   

“Wait here Bill, I think it’s within walking distance.”

I skirted the drifts on the road, but it was solid snow at the creek, which was a choppy gusher.

This was not a good sign because the camera was in an alder thicket on a silt bench a few yards from the creek and only a few feet above water in summer.

A few minutes later I found the alder thicket; normally 8-15 feet high, it was flattened by snowpack.  

I’m standing there thinking it would take a team with shovels and spuds to expose the camera, when I see a bare spot and a piece of weathered plywood.

It was the cover over the tunnel and camera.

I tugged it free like a crazed treasure hunter . . . and “Damn (expletives deleted)!”

The tunnel was flooded.

I yanked the stake free with the camera attached . . . and “DAMN! (more expletives deleted)!”  

Rust-colored water drained from the camera case.

I pulled the precious SD card, dried it, and headed back to the car with the dripping camera trap.

At San Francisco State University’s field campus we downloaded the file.  

The camera took 106 photos before unseasonal rain flooded the burrow at the end of January.

I was resigned to another failure as we scrolled through blank exposures and occasional pictures of vole, shrew, or chickaree.

Then the snow-white weasel appeared. On January 7^th. One image.

It was the last animal picture on the card.

Three weeks before the flood that ruined the camera.

     

Errant Mountain Beaver

Folks up here on the ridge were recently roused to declare their biophilia when a mountain beaver was reported swimming down the Butte Creek Flume.

One of our local naturalists, a retired bike-riding school teacher known by his avatar Forest, documented the rare event in video.

This is the first verified record of mountain beaver in Butte County, and the discovery begs the question: From whence the errant rodent?

I'm an enthusiast of these guinea pig size rodents, and I recognize their haunts when I see them, but I have never seen their signs in the county of Butte.

They require lush vegetation for food and live in moist habitats with shallow water tables, Their burrows often tap into underground springs.

I guess I have to look a little harder.

Arctos, an extensive database of zoological records, lists mountain beaver specimens from several counties in the Sierra Nevada, including Shasta, Plumas, Eldorado, Sierra, Nevada, Placer, Mono, Mariposa, and Tulare.

I suspect this particular rodent entered the flume voluntarily, swam around, and went with the flow.

But here's the rub. Its flume float could not have been longer than about 3 miles.

If the rodent had embarked on its swim further upstream it would have passed into a deadly siphon that conveys the water down and then up a ravine.

Even Houdini couldn't have made it through that siphon alive.

If the mountain beaver's odyssey started above the siphon, it had to travel by land to bypass the siphon and reach the flume's navigable portion.

Unfortunately, the neighborhood's flumes do not lead to suitable habitat for mountain beavers. So I doubt this rodent's trip led it to greener pastures.

It was an unusual event and it makes you wonder.

Did the mountain beaver abandon its home because of the drought? Or was it just a normal attempt to disperse that few people ever see?

We're lucky to have naturalists like Forest here.

One Month in Subterranea

This little movie is part of a continuing saga, a self-inflicted exercise in hope and frustration that started 4 summers ago when we found a collapsed mountain beaver tunnel in the northern Sierra Nevada.

In a strange way that narrow collapsed section of the tunnel resembled the shotgun-blasted stomach of Alexis St. Martin, the trapper whose misfortune set the stage for William Beaumont to become the grand old man of gastric physiology.

Like the gaping hole in St Martin's stomach, this mountain beaver's tunnel had a portal that exposed the mysteries within.

Collapsed mountain beaver burrows however are a dime a dozen.

What made this one special was that it opened up into an underground cavity big enough to accommodate a camera trap without blocking the passage.

Plus, this was not one of those thin-roofed sub-surface tunnels. This one was nearly 2 feet deep, making other cave-ins unlikely.

We started in 2010 by setting a still camera down there, a Sony s600 to be exact, and though there were lots of blank exposures the animal images were thrilling to see.

We learned that the mountain beaver's burrow system is a commons used by a lot of seldom-seen freeloaders like weasels, mink, and water shrews, not to mention great swarms of mosquitos.

Two summer's passed before I asked, "Why not video?"

It was an iffy idea, but I thought a few clips of the subway traffic would satisfy my whim and allow me to move on to other projects.

So I bought a home brewed DXG 567 from a fellow camtrapper and set it out in June, 2011 for the forthcoming workshop.

A bear cub unearthed the cam a couple weeks into the bargain, but not before the camera sampled some of the underground fauna.

In 2012 we tried again and discovered that chickarees actually mine the tunnels for truffles.

Now I was really hooked, even though the quality of the video schtunk.

The lens's field of view was too narrow, and depth of field was crumby.

So last winter I replaced the old lens with a $20 4mm wide angle lens from EBay.

The results are what you see above.

I am pleased with improved field of view, disgruntled with the focus, and flustrated with all the false exposures.

The camera is just too slow, and fixing it will be this winter's project.

My plan is to go back to the site and find all the entrances leading to that treasured tunnel.

If I can set external PIR sensors in the burrow entrances the camera will be rolling when the critters come cruising down the tunnel.

2012 Camera Trapping Workshop

2012 Camera trapping class:
Top row: Greg MacDonald, Hannah Stewart, Patti ten Boom Byrnes, Natalie Fenner, Timothy Fenner, Sam Dailey.
Bottom Row: Joshua Fenner, Bill Wilson, Gwen Dailey, Chris Wemmer, Doug Overman, Lance Milbrand, Caitlin Ott-Conn.  

Thunder showers and an electrical outage got us off to a slow start, but otherwise, the 4th camera trapping workshop at SF State University's Sierra Nevada Field Campus came off well.

Participants of past workshops helped the codger by setting their own cams in the Yuba country a month beforehand, and when the job was done we had a total of 15 in the field.

We were confident we'd have a few photos of Bruin. Large piles of bear scat seemed to litter one meadow where we set two cameras. 

But when we went to collect those cameras we found ourselves in the midst of a logging operation. The bears left us empty-handed.

The field campus provided ample opportunities for camera trapping, and back at camp, however, Patty ten Boom Byrnes captured video of a cub exploring a log. (Sorry I can't upload it.)

Doug Overman with his pre-Galileo
all purpose cam mount.   

Just down river from the tents Bill Wilson added a new species to our Sierra County mammal list -- an incomplete but unmistakable image of a river otter.

Bill Wilson's river otter visited a log jam below camp.

Not far away RandomTruth's cam snapped a bobcat.

Above camp Caitlin Ott-Conn got a photo of an upright showtl -- not a pose commonly caught on our cameras.

The class harvested the usual assemblage of cute rodent pictures.

We added the long-eared chipmunk to the species list -- and you can see here one of its distinguishing marks -- long almost unchipmunkly ears.

The Douglas squirrel or chickaree

Chickarees were the usual early morning and late afternoon camp visitors, but our subterranean video cam once again caught them doing mysterious things in mountain beaver burrows.

Golden mantled ground squirrel.

Golden mantled ground squirrels were already plumping up for hibernation. If the bitter cherries are any indication, there will be heavy mast crop this fall.




Jake's cam also got an image of a Wandering shrew (Sorex vagrans).  See if you can find it.

To celebrate the "strenuous life", we forded the Yuba's north fork and climbed Deadman Scree.  Everyone marveled (I hope) at this geological phenomenon and savored a habitat that cooks in the midday sun but hides an ice age climate in the underworld beneath the rubble.  

On the Deadman talus slope with Lance in video-documention mode.  

We had a couple of camera failures, but still managed to capture some portraits of bushy-tailed wood rats in various stages of development.

A heartfelt thank you to the "alumni" who helped me out on Tuesday night by making presentations about their own camera trapping discoveries.

Jake and Christian compared still pictures with video clips, their message being that if one relies entirely on still pictures one gets snapshots of a much bigger story. Video clips contain much more information. 

Random Truth presented his ideas about close-ups and serendipitous sets with gorgeous examples of woodrat activities in the coastal range and critters from the eastern Sierra.

A serendipitous mountain beaver set -- no "Aplodon,
but a handsome Western tanager (Sam Dailey's photo).

My subterranean cam yielded some chickaree and showtl footage, but a bear cub curtailed that set when it uprooted the cam and turned it on its back. (More about the challenges and risks of subterranean cam-trapping soon.)

I'll be heading back in another week or two -- as soon as I get some special mounts made for some odd sets.

Many thanks to the "alumni" from previous courses, Jake, Christian, Sean, and Random Truth, and to Bill Wilson for assisting with local logistics during the full week.

Last but not least, thanks to the class for enthusiasm and hard work.

One of a series of time lapse photos taken at lunch with a Canon A630. The camera was hacked with the Canon Hack Development Kit (CHDK). We also demonstrated motion detection.

Showtl's Underworld, Part 2

Six hours after we left, Showtl made its first appearance.  

What a difference a month can make during the growing season.

We bumbled about looking for the underground cams.

Alders in full leaf and knee-high grass covered the landmarks we expected, and we fell back on the GPS and Audrey's cognitive map to find the underground cameras.

But showtl didn't let us down.

Our rodent made almost daily appearances, which means the site was probably located near its nest.

Only 21% of 281 exposures however contained animals. The rest were blank images.

Normally we'd blame this on moving vegetation and phantom puffs of hot air which the infra-red sensor can't distinguish from animals, but this doesn't explain false exposures in the showtl's cool burrow.

It is more likely the rodent was zipping back and forth, and the camera was often too slow to get pictures of it.  

Despite false exposures, we still got 57 images of our quarry, and what you see here are the best. 

What you don't see are the two predators lurking in the tunnel.  

They're coming soon. 

The Showtl's Underworld

My obsession with showtls took a new turn this summer.

We attempted our first subterranean camera trap sets.

Two hours later two cameras were positioned to capture photos of the beastie in its underworld.

The showtl's tunnel was squarely in the middle of an alder thicket, and Montana Carl announced his intention to stay clear of alder, which he claimed had taken liberties with his person ever since the first day of the workshop.

In point of fact, springy alder limbs had been goosing all of us.

Making the sets therefore fell on the shoulders of the more agile young folk, while the two codgers sat on the sidelines to kibbitz.

The first task was to find the best location.

Several cave-ins had left gaping holes, much bigger than showtl burrows, that murmured of water and mosquitos within.

"Who's gonna stick their arm down there and take some pictures of the tunnel?"

Seabass volunteered.

The pictures showed us that the tunnel was anything but straight, and passed through a morass of buried timber and roots.

In some places it was an open trench. 

Next, we had to decide which cave-in gave the best subterranean perspective.

Snow water had created a small cavern immediately inside one of them.

It was an ideal situation for a camera trap: we could stake the camera and yield right-of-way to passing showtls.

Seabass drove a 1" pipe into the bed of the subway, and lowered the cam on its mount to just above the water.

The afternoon dragged on as we fine-tuned the camera's position, but we were all fluffed up with our cleverness, and for good measure we hurriedly staked a second camera down another chute.

Then we headed back to camp for a well-deserved happy hour.

Herman the Ermine was alurkin'

Herman the Ermine after cropping

"Study your photos carefully", is my codgerly counsel to novice camera trappers. "Its easy to miss the little guys."

As I gleefully reviewed Bill's showtl pictures the other day I failed to notice Herman the Ermine lurking in the background.

This afternoon Herman finally caught my eye.

Here's the uncropped photo, taken two and a half minutes before Showtl appears in its burrow.

Herman the Ermine before cropping

It could have been a close shave.

We've gotten three photos of weasels (long- and short-tails) in the North Yuba watershed, and they've all been in Aplodontia colonies.

This got me to wondering.

How does the showtl avoid or fend off fatal encounters with predators that can enter their burrows?

Does it have any anti-predator ploys?

You just don't see earth-blocked burrows in showtl colonies.

They don't have the pocket gopher's compulsive burrow-plugging habit which seems to hold many predators at bay.

In fact, from the number of burrow openings you'd think they had an open-door policy with weasels.

Here's a sketch of the burrow system and openings from Charles Camp's study of Aplodontia in 1916.

The strange reality is that showtl knows how to block burrows, but reserves the measure for its underground leaf and root pantries.

Camp wrote,

"A singular habit has been noticed in connection with the storage of food. In a burrow excavated at Point Reyes the entrances of two of the food storehouses were found plugged with large pellets of earth evidently manufactured by the animal for this purpose. These earthen balls were one to two inches in diameter and very hard and dry, evidently from being handled a good deal. It is curious that the outer burrow entrances are not similarly plugged." 

Here's a hypothesis.

Short sections of water-filled tunnels, a water seal of sorts, may bar weasels from entering the showtls nest cavity.

Camp didn't describe such water seals, but if we examined more burrows we might find that they exist.

The problem is that recreational burrow-diggers are hard to find these days.

But one thing is certain. The weasel that nails a showtl is well fed for several days.

An adult showtl outweighs an adult male long-tailed weasel by a factor of 3 or 4.

Herman the Ermine is 1/16th the size of the rodent, so the windfall of flesh would be much greater.

But do ermines take down showtls?

I suspect so, at least young ones.

An ermine is a fierce little killer, and if it can wrap its jaws around the showtl's throat the struggle would be brief.

Showtl emerged 2.5 minutes after Herman moved through

References

Camp, C.L. 1918. Excavations of burrows of the rodent Aplodontia, with observations on the habits of the animal. University of California Publications in Zoology, 17(18):517-536.

Spring cleaning

We descended on the alder thicket on the Yuba River back in June-- a band of eager camera trappers hungry for photos of the enigmatic but endearing showtl.

When it comes to camera trapping, showtl seems to be on the bashful side.

You have to wait a week or more before the adorable head with humanoid ears pokes out of the burrow.

But this time Bill Wilson got a nice series of showtl pictures over a period of two weeks.

This animal's watery burrow had an apron of knuckle sized rocks, and as you can see in these stitched photos, those rocks weren't washed out by water.

Showtl was doing its spring cleaning, while the plants were growing like crazy.

I wonder how much gold the showtls have unearthed since the 49ers?

Thanks Bill, for letting me show your catch.

Sunrise showtl

Dawn chorus and showtl appears
in scattered light of frond and leaf
Through the firs sunlight breaks

As Codger followers by now realize, I am just back from a week at SF State University's Sierra Nevada Field Station, where images of showtls have moved me to feeble attempts at poetic expression. 

The class discovered their camera-trapping instructor was obsessed with the showtl, and if you don't know anything about mountain beavers, sewellels, showtls or Aplodontia rufa, read here.

And by the way, this image was the first attempt at showtl espionage by the ladies of the class.

I'd say they did pretty well. 

As I wind down and unpack, I'll be working up the images.

More on the workshop this week, and thanks to Carl for photoshopping this problematic image.

(Now I am off to the flume where I lost my glasses this afternoon.)

Annual Aplodon Photos

Whether you want it or not we're serving mountain beaver today, or if you prefer, call it showtl or aplodon.

These photos were from a camera I set a month before the camera trapping workshop on the North branch of the Yuba River.

I found but one burrow in the alder thicket where the colony is located, and was concerned that the population had crashed.

But I was wrong.

The burrow was active a month later when I took the class to check the camera, and the thicket had quite  a few additional burrows.

The animal above came from a watery tunnel, and I have found quite a few burrows now with water running freely from them.

But most exciting was this photo of two fellows in one frame.

They look to be a bit smaller than the previous animal(s), so I am guessing they are young of the year. 

The color difference is due mainly to differing flash exposure. 

The camera had taken 32 pictures of the rodents, but only one photo during the first and second week. 

All the other pictures were taken on the 22nd and 24th day of the set. 

In my experience aplodon aren't camera shy, but often they don't make their first appearance until two or three weeks have passed.  

You must wait patiently for the rodent with humanoid ears to photograph itself.

But while you wait the plants between the camera and the burrow grow with a vengeance.    

My advice is this: when you make your set show no mercy for those tender sprouts. 

Bring a big machete and cut them down.  

If you don't, you will get some wonderful photographic studies of plant growth, but no images of the rodent with humanoid ears.  

A remote spring on the Yuba

A spring feeding the North Yuba River, Sierra County, CA

Red fir logs had blocked the spring and created pools in several places. 

I chose this one, about 75 yards below the source to set a camera because it seemed most accessible to wildlife. 

Ferns, Delphinium, various unidentified herbaceous plants, and a few small mountain alders blanketed the stream for much of its length. 

The rest of the area was practically devoid of ground cover, which I understand is typical of red fir forests.

A few species of birds visited the pool -- and you birders out there, don't hesitate to correct my identifications.

Hermit thrush

Townsend's solitaire

Saw whet owl

Robin and unidentified fledgling assumed to be a robin

I expected the usual rodents -- red and gray squirrels, golden-mantled ground squirrels, shadow chipmunks, and perhaps a wood rat. 

 

Aplodon crosses the rotten log forming the pool.

But here where I found no signs of aplodon -- burrows or plant cuttings -- one showed up on two consecutive nights. 

Aplodon wades through the water on its way to who-knows-where.

 

I thought I was starting to know where to predict their occurrence, but I guess I am still climbing the learning curve.

The sierra got its first snow this past weekend and soon the roads will be closed, but next spring I'm going back to this ravine and I am going to look for burrows and other sign very carefully.

I am also going to camera trap the length of the spring to see if there is a resident population. 

More plans, more work, more fun. 

Aplodon done gone away

It's always a thrill to get a weasel,

but I was looking for Aplodon (= mountain beaver).

West branch of the Yuba River, Sierra County, California

This wasn't the lush alder thicket I had worked back in early summer. 

The undergrowth was trampled and dry.

Deer had broken the dense clumps of Delphinium, and only a bear could have demolished the red fir log I had used a few months ago as a walkway into the thicket.

But I found the camera trap right away, and expecting an assortment of birds and small mammals I opened it to see if the camera still had power.   

Damned if the batteries didn't work! 

The next move in the ritual is NOT to start viewing the pictures. 

First I check the number of photos to find out if the catch was good or bad. 

What!  Only 4 photos?

That explained why the batteries still had power.

Yes, I was pleased to get the long-tailed weasel.

It is evidence that they forage in mountain beaver burrows, and you have to marvel at a predator that takes down prey 2-3 times larger than itself.

But how could this runway and burrow yield so few photos in a period of 2 months?

Last year the burrows were teeming with activity.

There's always something to learn  from this game and here are my thoughts.

First, I don't think the weasel cleaned out the colony.  

After giving it some thought, I remembered camera trapping  in Point Reyes National Seashore  a couple years ago.

Aplodon burrows that were active in early summer seemed abandoned in late summer. 

In both areas the active burrows were damp and the inactive ones were dry and dusty.

When the soil dries up mountain beavers seem to move to areas where the soil is moist. 

In winter and spring when soil moisture is more uniform they move back into the old burrow systems.  

That's my working hypothesis. 

 

Aplodon's watery subway

Aplodon's watery subway in a small lush grassy area 

with an abundance of lupine, Sierra County, CA.

As far as I can tell, mountain beavers don't mind watery tunnels.

Most of their burrows are in relatively moist soil, and on slopes where soil drainage is good.

A relatively dry Aplodon burrow 

between roots of white alder. Sierra County, CA

But in some burrows water trickles freely.

The green vegetation inside indicates an active burrow.

A new acquaintance in Sierra County showed me this tunnel system, where at least some sections of the burrow rest right on the water table and just a few inches below the surface.

These little charmers do some serious root grazing to clear a passage right under the sod, and I imagine the remaining root mass gives them a good coat brushing every time they scoot down the tube.
 
My friend discovered this colony in an unusual way. 

He was driving up the highway when he saw a bush making its way across the asphalt.

It wasn't on fire, but it was a strange vision all the same and it led him to a small Aplodon colony just above the road shoulder.

The rodent was removing bush lupines across the road and hauling them to its burrow on the other side.

This bush hauling business isn't unusual. You commonly find alder branches curing near their burrows.

Earlier this month I asked a Plumas County resident if he had ever seen mountain beaver. 

He paused a moment and said, "Yeah, and I shot it".

OhmyGodHowCouldYouAndWhy?!

It was cutting his bean plants and hauling them away. 

Since then the colony on his property hasn't gotten into trouble. 

But back to watery subways. 

When I was camera trapping for these fellows in Point Reyes National Seashore (check here) I got the impression that the most active burrows were near wet lush places. 

In early summer the active burrows were widespread at the bottom of the ravine.

They riddled moist soil and boggy areas beside springs, and above ground the vegetation was green and rank.

When the vegetation had dried up and much of the ground was drier in August and September there were fewer active burrows to be found.

Curing haystacks (in this case lupine) 

are a sure sign that Aplodon is working the area.  

The seldom seen showtl (or aplodon)

I set four camera traps in Sierra county a month before the camera trapping workshop, and was mighty pleased to find that mountain beavers -- hereinafter show'tls or aplodons -- occur in the drainages feeding the Yuba river.

Yes, from here on out I am calling them "aplodons" or "showtls". They deserve a catchy vernacular tag or a name (like "simple teeth") befitting their unique evolutionary position.

Let's forget the term "mountain beaver". Yes, like beavers they are excellent swimmers and waterway engineers, but there the resemblance ends. The name boomer doesn't cut it either. The only report of such a sound is now over 130 years old.

Then there's the name "sh'auch" used by the Indians of Puget Sound. It meant "creature that creeps in the undergrowth", and you can guess why that didn't take. The other moniker -- "sewellel" -- is said to have been the Indian term applied to robes made of their furs.

Enough. Back to the workshop. . .

When it commenced on July 21, the cams had been in the field for a month. Knowing that camera trapping is often slow business, I wanted to fire up the class at the outset by showing them the seldom seen showtl.

The gamble paid off. After I had rambled at length the first morning about camera trap sets and camera attachment methods, we climbed into the nearby thicket, found the cam, and clicked through the pictures.

A beady-eyed rodent finally appeared in the LCD, and being topless, she disclosed her sex within the first few pictures (notice that I don't confuse sex with gender). We didn't realize this until she was displayed on the computer screen.

The fact that she was bare-breasted has special significance. Female aplodons have very hairy nipples when cycling, pregnant, or lactating. We're talking about "dense patches of black hairs". Though a sign of showtl womanhood and of certain adaptiveness, it is not an enviable trait. It's likely that this bare-nippled girl was born this spring.



Aplodon colonies in this part of the sierra are in sprawling alder thickets bordering the Yuba river and its tributaries. We found numerous nipped twigs of alder, but the pruned stubs were dry and gray. I was almost convinced that alder is a springtime food until we found a burrow with leafy wilting branches.



Lewis and Clark were the first to report on aplodon's climbing ability, but University of California mammalogists Joseph Grinnell and Tracy Storer had their doubts. Lloyd Ingles proved it with photography.

Ingles built an enclosure at Huntington Lake in the southern sierra, and stocked it with two females from a nearby colony. They climbed 20 ft up into white firs and lodgepole pines, and in 4 weeks pruned off most of the branches. Aplodons are respectable if not acrobatic climbers of trees and shrubs, but they have to descend butt-first.



I thought that aplodons would be easy pickings for the workshop participants, but I was wrong. No one else got their photos.

When I checked the date and time stamps on my own pictures I realized why. The animal had visited the burrow only on three occasions, and the first visit wasn't until three weeks had passed. Aplodons have extensive burrow systems with multiple openings.

During the course I tried to get more photos by planting my small camera traps in underground tunnels with caved in ceilings. Every sign indicated they were active tunnels, but no aplodon showed it face.



References

Camp, C.L. 1918. Excavations of the burrows of the rodent Aplodontia, with observations on the habits of the animal. Universitu of California Publications in Zoology 17(18):517-536

Godin, A. J. 1964. A review of the literature on the monjtain beaver. Special Scientific Report -- Wildlife No. 78. U.S. Department of the Interior, Fish & Wildlife Service, Bureau of Sport Fisheries and Wildlife, Washington D.C.

Ingles, L.G. 1960. Tree climbing by mountain beavers. Journal of Mammalogy, 42(3):120-121

Scheffer, T.H. 1929. Mountain beavers in the Pacific Northwest: their habits, economic status, and control. US Department of Agriculture, Farmers' Bulletion No. 1598:1-18