A White Winter Weasel

The short-tailed weasel or ermine, Dec 19, 2013, 1840 h

I just scratched the white winter weasel from my camera trapping bucket list. 

At least the white short-tailed weasel (Mustela erminea). 

The white long-tailed weasel (Mustela frenata) remains to be camera-bagged.

White weasels of course are just brown weasels camouflaged in white winter coats. 

You find them where you can rely on long snowy winters, which is north of the 40th parallel.  On the mild west coast, the white-weasel-line jogs north into British Columbia.   

I bagged my white weasel near Yuba Pass on a steep north slope, in a jumble of broken granite shaded by red fir.

Some time in the past a large mass of granite cleaved and released a large flake of stone that slid several feet and settled against its mother.

The result was a narrow slot, a shelter, the kind of place small boys and codgers in their second childhood love to explore.

I was ready to camtrap "the granite flake" two summers ago, but a yellow jacket nest changed my mind. 

It was only the size of a grapefruit, but big enough to scare me off.  

The nest was gone last fall, so I set the camera on October 8th using civetone and castoreum as elevated scent lures.  

   

View from north opening.

View from south.

Bill and I checked it last Wednesday. The Lithium AA batteries lasted 94 days, and in addition to the white weasel -- here's what we got: 

Montane vole (Microtus montanus): 6 visits/8 photos

Bushy-tailed wood rat (Neotoma cinerea): 8 visits/13 photos. Last visit:Oct 18. Here it gathers lichen as nest material and/or food.

Brush mouse (Peromyscus boylii): 58 visits/146 photos. Many photos recorded one or more of these characters gathering papier mache from the wasp nest.

Trowbridge shrew (Sorex trowbridgii): 1 visit/1 photo (Nov 14)

Long-eared chipmunk (Tamias quadrimaculatus): 11 visits/14 photos (Last visit: Nov 21)

Chickaree (Tamiasciurus douglasii): 11 visits/14 photos 

You all know, of course, that we're in a bad bad drought.

There was little snow on route 49 until we reached 6000 ft. Normally it would be down to 4000 ft.

Below the current snow line those white winter weasels are an advertisement to predators, mainly carnivores and birds of prey.

Not to worry my friends, the furry and feathered agents of natural selection have already started to fix the problem.

[thanks to "Bill W, MJC" for the good company and watchful eyes]

References

King, C. 1990. The natural history of weasels and stoats. Cornell University Press, Ithaca

Hall, E.R. 1951. American weasels. University of Kansas Publications, Museum of Natural History 4:1-466.

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Will the real Ermine please stand up

September 3, 4:39AM -- in the showtl's underworld

We are just back from the north fork of the Yuba River.

Yesterday, the Codger, the Redhead, Audrey, and Fred pulled the last three camera traps, and I am terribly amped.

The picture above is one of the reasons.

You may recall that the codger was uncertain that "Herman the Ermine" was correctly identified in a recent "underworld post".

A few commentors thought the suspect was an American mink.

The unmistakable ermine pictured above confirms that the previous mustelid was indeed Slinky the Minkie.

This ermine was photographed in the same Aplodontia (=showtl) tunnel where the mink made its appearance last month.

To get an idea of the relative sizes of this little predator and its prey, compare the two pictures, which I have cropped more or less to the same size.

Like the mink, the ermine evidently failed to find the showtl, which showed up 6 days later.

Its absence makes you wonder if predator detection changed the rodent's use of the tunnel system.

Anyway, we're not done yet.

We staked out several Aplodontia burrows for camera trapping next year.

Our winter work is cut out for us. We've got to get faster cameras so we can diminish the number of false exposures down there in the showtl's underworld.

There's a lot of traffic and probably a few visitors that are just too fast for our cameras.

And to give you a bigger view of the showtl's busy underworld, here's an uncropped photo.

The Showtl's Underworld, Part 3

Herman the Ermine made but one alarming appearance, August 1 at 12:45AM.

Nine hours later the showtl was back, safe and sound.

Other species find Aplodontia's digs to be popular hangouts.

During a trapping study of Aplodontia burrows in the 1950s, Egbert Pfeiffer caught spotted skunks, long-tailed weasels, an ermine, mink, chickaree, dusky-footed and bushy-tailed woodrats, several species of mouse, and none other than Big Sally -- our Pacific Giant Salamander.

Other field workers added the striped skunk, raccoon, badger, marten, the snowshoe hare, more rodents, the coast mole, and the charismatic shrew mole, another Codger favorite (here's why).  

As a meeting place for some intriguing and rarely photographed species, Aplodontia burrows have much to offer.

[Note: I am not absolutely certain this little predator is not a mink -- please speak out if you have a definite opinion.]


References

Pfeiffer, E.W. 1953. Animals trapped in mountain beaver (Aplodontia rufa) runways, and the mountain beaver in captivity.  Journal of Mammalogy, 34:396.

Carraway, L.N. and B.J. Verts. 1993. Aplodontia rufa. Mammalian Species No. 431:1-10.

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.