More subway traffic

An adventuresome chickaree was one of two new sightings in the showtl's subway.

It was photographed exploring the tunnel twice, in the morning and afternoon.

JK of Cameratrapping Campus had a similar chickaree (or Douglas squirrel) experience at another showtl burrow a few miles from here.

What's going on? Are they hunting for truffles down there?

Chickarees are well known as fungus connoisseurs, but I know of no reports of their activities as subterranean fungus-foragers.

A long-tailed meadow mouse also trolleyed through a few days later (mid morning and late afternoon).

Most curious however was another appearance of the water shrew.

Is its peculiar posture just a coincidence or is it pushing mud in the middle of the tunnel?

The mud appeared on August 27 shortly after midnight, and the shrew was photographed 21 hours later, and once again 2 days after that.

After that the mud pile slowly disappeared.

I'd love to know what it was up to.

I am sure the showtls' tunnels hold many more secrets of natural history. 

The Showtl's Underworld, Part 4

Can you see the bristles on its hind feet?

Well, neither can I.

Bristled feet are a diagnostic characteristic of the world's smallest diving mammal -- the American water shrew.

The photo doesn't do justice to the shrew's hairy feet, but that doesn't mean it isn't Sorex palustris. 

It matches the other external features.

Water shrews look like miniature torpedoes when they dive for amphibians, fish and aquatic insects in fast-flowing streams, and they do it all while dog paddling and twirling their tails like propellers.

Shrews (and especially shrews of the red-toothed tribe or Soricinae) live in the fast lane, pushing the envelope of energetic possibility.

They have relatively high thermal conductance, which means they are not well insulated, but their compensation for this deficiency is a high basal metabolic rate (BMR) and high body temperature (38.6 degrees C = 101.3 F).

Thus, shrews are fascinating topics of investigation, but as subjects of energetic study they are frustrating in the extreme.

Within the physiologist's metabolic chamber or respirometer, research subjects are supposed to rest peacefully in a state of post prandial quietude as the equipment measures their oxygen consumption and carbon dioxide production.

And they should also be "postabsorptive" -- not digesting food -- because digestion has a caloric cost and raises metabolism.

Shrews are not good at this, because they are fussbudgets around the clock and they rest only briefly.

Their basal metabolic rate is so high, that the time it takes for food to pass through the digestive system ('throughput" to physiologists, "poop time" to most readers) is about an hour.

Count yourself blessed if you ever see a water shrew.

You have seen a rare sight -- the world's smallest diver, and one of the faster poopers in the west.

Question: the practitioners of what outdoor recreation have the best chance of seeing water shrews?

Post you answer in the comment section, and speak up if you yourself have seen one in action.


References

Gusztak, R.W. , R.A. MacArthur, and K.L. Campbell. 2005. Bioenergetics and thermal physiology of American water shrews (Sorex palustris). Journal of Comparative Physiology, 175:87-95.

The little guys who also show up

These are pictures of "incidentals", the little guys who also show up. Aplodon was my target species at this set, but there were several passersby in the vicinity of the rodent's burrow. I tentatively identified the creature above as the water shrew (Sorex palustris), and the brown-colored one below, if you can see it, I am tagging as the vagrant shrew (Sorex vagrans). As I mentioned though in the workshop summary (a couple posts back), these are tentative identifications.



Three of us photographed long-tailed voles (Microtus longicaudis). They were all filmed moving about day and night in the alder thicket.



Of the birds, this yellow-rumped warbler is unmistakable. The other photo of it revealed fewer diagnostic features.



Though wood rat pellets and cached cones were abundant in the granite recess of the following camera set, the mouse was the only visitor. It could be a North American deer mouse (Peromyscus maniculatus) or a brush mouse (Peromyscus boylii). Based on coloration (not well rendered here) I am guessing it's the latter. It was photographed at 6000 ft on a large cliff face near Yuba Pass.