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Native Californian, biologist, wildlife conservation consultant, retired Smithsonian scientist, father of two daughters, grandfather of four. INTJ. Believes nature is infinitely more interesting than shopping malls. Born 100 years too late.

Sunday, October 23, 2011

The Restless Haystack

A mountain beaver or showtl on the job -- is it making hay or pitching its tent? 

In 1995 Mark Johnson published an article on tents that cover the burrows of mountain beavers.
"Supporting sticks were placed over and across the entrances. Then, sticks were placed perpendicular to these over the entrances. Finally, leafy sticks of big leaf maple (Acer macrophyllum), sword fern (Polystichum munitum), or both were placed across the sticks concealing the entrances." 
The tents were clearly the handiwork of the showtls and not the caring gesture of a passing Sasquatch.

Not all burrows had tents, but Johnson thought they may keep burrows dry in a rainy climate.

Though usually agreeable, showtl enthusiasts have at times disagreed about the animal's tolerance of water.

A pioneering student of the showtl, C. A. Hubbard opined that the rodent shuns watery tunnels, "because Aplodontia cares for water only as  a drink."

Lloyd Glenn Ingles on the other hand averred that, "Living as it often does near water, the animal is a fine swimmer."

Yours truly and his student camera trappers have also given photographic proof that showtls and their neighbors have no qualms about scooting through watery tunnels.

I have the feeling that the showtl's tent may be a drying rack for plant cuttings, that is, nothing more than a haystack, and haystacks have also been reported numerous times in the scientific literature.

The big question is about the criss-cross arrangement of the sticks.

Are they an act of God or an act of mountain beavers?

I've assumed they were an act of God, that they just happened to be there as they had fallen from the trees.

We have actually removed a few sticks from some burrows for better pictures, and if the rodent replaced them with others, I for one didn't notice.

But I am greatly intrigued by Johnson's suggestion, though apparently based on circumstantial evidence rather than direct observation.

A rodent that builds a tent or a drying rack by dragging sticks over its burrow is a remarkable rodent.

It's a tool user.

So confirming Johnson's tent-building observation is on the list for next year's showtl work.

If you haven't seen a showtl's haystack, here's a sequence of 30 photos taken during a week near Yuba Pass, California.

Try to stay awake. It's less than a minute and the action gets exciting at the end.


Hubbard, C.A. 1922. Some data on the rodent Aplodontia. The Murrelet 3(1):14-18.

Ingles, L.G. 1965. Mammals of the Pacific States. Stanford University Press, Stanford, California.

Johnson, M.K. 1975. Tent building in mountain beavers (Aplodontia rufa). Journal of Mammalogy, 56(3):715-715.


john said...

Maybe the Mountain Beaver, (that's the one name I can remember) likes it's salad to age a little, or dry out before eating it?

Camera Trap Codger said...

I'm sure they prefer dry bedding and settle for dry salad in the winter.

randomtruth said...

Perfection, Chris. I think boomer is drying the foliage out to keep it from molding once it is moved and stored down in the wet burrow.

Jacques Prescott said...

In his 1968 PH D thesis on Mountain beaver (Oregon State U.), E.H.Voth felt that haymaking behavior may be related to improved succulence or nutritional quality of the vegetation. Also, it may involve the psychological well-being of the animal by reducing the number of times the nest and feeding chambers are opened to bring in vegetation. As for the arrangements or specific placing of the twigs and leaves, A.W.F. Banfield (Mammals of Canada, 1974)mentions that those haystacks are often well arranged, stems being oriented in the same direction. Haystacks thus serve many purpose: covering the burrow entrances, serving as nest material and food supply. No wonder our showtl or Sewellel (The name Sewellel Beaver comes from sewellel or suwellel, the Chinook Indians term for a cloak made from its pelts) is taking such great care in building haystacks. (Other names for the Mountain Beaver include whistler, Chehalis and mountain rat). Boomer is definitely a sensible animal.

Camera Trap Codger said...

Thanks Jacques. We'll be unraveling the secrets of these little cuties a bit more next year, and Audrey who took the workshop has become so enamored of them that she is planning a project. The mountain beaver name I like best is "kick-willy",