Within a junk pile

What goes on in a junk pile of old fence posts, broken gates, wire, and corrugated tin roofing overgrown with willows? We got a glimpse when we set a camera inside.

  

Slinky grim reaper of the underworld

Long-tailed weasel with prey.

There's a good reason weasels are long and skinny.

It's "essential to the profession of a burrow-hunting rodent predator...", wrote weasel expert Carolyn King.

This photo of hunter and quarry was taken in a mountain beaver burrow, and it would seem to prove the point.

But did this long-tailed weasel kill the golden-mantled ground squirrel in the burrow?  Or did it dispatch the rodent above ground and then drag it into the burrow?

Golden-mantled ground squirrels are common in the area, but you find them in dry open coniferous forests rather than the riparian woodland and thickets where mountain beavers dig their burrows.

I've camera trapped this mountain beaver burrow almost seven months in the past 4 years, and the graph shows that golden mantled ground squirrels are not among its users.

I suspect the weasel killed the ground squirrel above ground and dragged it into the burrow to feed out of harms way. That's how weasels operate.

But as the graph shows, a weasel is more likely to encounter a mountain beaver in this burrow than a golden-mantled ground squirrel, and the chickarees and voles down there certainly run the risk of meeting this slinky grim reaper as well.

One other observation: the camera failed to record the resident juvenile and adult mountain beaver during the last sampling period. At least one mountain beaver has always been present.

Has the weasel appropriated this mountain beaver's underworld?

Is its nest now lined with the soft pelts of the previous residents?

I'll update you next month.

A chickaree shells a fir cone in the underworld earlier this month.

Reference:

King, C. 1989. The natural history of weasels and stoats. Cornell University Press, Ithaca.

Video vision in the tunnel - Part 2

Our first attempt at subterranean video this year was disappointing.

Had the camera been placed differently the footage could have been better, but there was also the problem of the curious bear cub that dismantled the set.

The subterranean action however was more than enough to call us back.

Our second attempt in August was in a different segment of the same mountain beaver (=showtl) tunnel.

This time I came prepared with a customized mount that could be spiked into the hardpan on the floor of the tunnel and nailed into the log embedded in the silt bench above the tunnel.

Set 519.3 after being disguised
with a large flake of red fir.

The camera post was spiked and wired
to the embedded log. 

We covered the vertical hole with a large flitch of wood.

As you have seen in Part 2, the bear didn't show, and if any subterranean critters bumped into the camera they didn't move it.

















But I still didn't get the angle of the camera quite right. It should have been aimed up into the tunnel. The focus was also off, and the microphone made hideous sounds (which I'll try to remove -- sorry about that).

The camera in situ as we uncovered it
33 days later.

I just replaced the lens of the DXG 567v with a 4mm wide-angle CCTV lens, which will take in a much wider view.

We'll try again next spring.

Long-tailed weasel and rodent cornucopia

A long-tailed weasel (Mustela frenata) checks out the castoreum stain left as a scent lure.

Yuba River (North Fork) drainage, Sierra County, California

I wasn't expecting miracles at set 574, but it always seems like a miracle when I camera trap a weasel. Especially a blue-eyed weasel. (Just kidding, folks; those pretty blue peepers are the reflection of the camera's flash from the eye's tapetum lucidum).

This weasel sniffed the castoreum just long enough for a single photo.

The set was under a boulder on a steep slope in red fir forest.  A few de-scaled pine cones identified it as an undercover messhall.

The camera snapped 431 photos in 33 days, but 60% were blank images most probably triggered by fleet-footed rodents.

Long-eared chipmunk (Neotamias quadrimaculatus)

Possibly a brush mouse (Peromyscus boyleii)

Deer mice and long-eared chipmunks accounted for most (=80%) of the wildlife photos.

Long-tailed vole (Microtus longicaudus)
shows its bicolored tail

A bright-eyed long-tailed vole posed nicely for one photo,

Northern flying squirrel, a meat eater. 

and northern flying squirrels left 13 images during three visits.

Chickaree (Tamiasciurus douglasii) 

Chickaree's visited 10 times and left 14 photos.

Even the deer mice sniffed the castoreum.

Every species of mammal left at least a few self portraits while sniffing the irresistible castoreum.

The stuff is a truly broad-spectrum attractant for mammals and indispensable to this camera trapper.


I can't identify the only critter that ignored the scent lure.

The best of three photos of the "mystery chick".

At first I thought it was a scruffy molting wren.

But now I wonder if it's a chick of a blue (sooty) grouse, mountain quail, or even a sora rail?

Early September would seem a bit late for a chick, no?

Any opinions out there?

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. 

 

A charismatic micro-vertebrate

It came a few minutes before midnight on July 9th, and paused next to the mountain beaver burrow when the camera powered up. There was a quiet whirring sound inside the camera trap about three feet away. It took the picture as the weasel peered at the camera's silhouette in the thicket. Hallelujah -- the camera didn't fail me.

My camera traps are a bit slow to catch weasels, which are mammals of perpetual motion, but this time I was lucky. For 3 seconds the weasel's attention was riveted by the sound that usually scares away the coyote.

I was thrilled. Seeing a weasel is always a treat. Their movement is lyrical. You are lucky if you catch a fleeting glimpse, but you are blessed if you can watch them for several minutes.

I've had my best weasel viewing experiences in northern California'a coastal scrub and near timber line in the Colorado Rockies. Pure serendipity.

Now, if you want a real treat, go here and download this video of a family of long-tails playing at the entrance of their burrow here at Point Reyes National Seashore, where I took this picture. (You will need Real Player to view it.)

Acknowledgments: Many thanks to the National Park Service, for permission to conduct a camera trap wildlife survey in Point Reyes National Seashore.