About Me

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Native Californian, biologist, wildlife conservation consultant, retired Smithsonian scientist, father of two daughters, grandfather of 4 small primates. INTJ. Believes nature is infinitely more interesting than shopping malls. Born 100 years too late.

Friday, August 29, 2008

The imagined threats of camera traps

Now that the dust has settled from Mr Benson's recent article on camera trap Papparazzi, I feel duty bound to set the record straight about misleading statements that aroused a few to mount their high horses.

First, the author's contention that "massive deployment" of camera traps "may be hurting the animals they are used to study".

If this wasn't an otherwise serious article I'd swear the author was pulling our legs. I mean . . . "Massive deployment?" Like the invasion of Normandy?

This and other statements alarmed a few gullible readers, but most of the commenters to the article didn't buy it. This blog received over 40,000 hits resulting from the article, and most readers were apparently indifferent.

Here's my suggestion to the author and other suspicious readers. The next time you fly across country look down and visualize the spacing of all those deployed camera traps. If you still see "massive deployment" take Benson's quoted figure of 300,000 and try calculating the number of cameras per acre of public and private land.

Now, how do you think that figure compares with the density of automobiles, snow mobiles, and ATVs out there? Shall we compare their impact on wildlife?

The author got it into his head that cameras "can" hurt wildlife.

But then I thought, you're getting old, codger, and the English language is changing.

So I looked up "hurt" in Webster's.

"Hurt: vt (ME hurten): to inflict with physical pain; WOUND; to do substantial or material harm to: DAMAGE; to cause pain or anguish to: OFFEND; to be detrimental to: HAMPER syn. see INJURE."

Yes, he's stretching it quite a bit.

Why? I did my best on the phone to share my experiences with him. You can read many moods from camera trap images -- indifference, distraction, curiosity, and occasionally surprise. Perhaps even rare cases of aggression, though I doubt it.

He didn't want to be confused with facts, and concluded that "If such provocation were consistent and widespread—and the increasing popularity of camera traps means that it is rapidly becoming both—it could lead endangered animals to waste energy or avoid fruitful areas for foraging or hunting."

A little knowledge is dangerous, but he was cautious enough, or perhaps uncertain enough to say it "could" happen.

The truth of the matter is this. If camera traps were so damn disturbing to wildlife, they wouldn't take so damn many pictures of wildlife.

(I'm not through yet. In future posts I will discuss some concepts of animal psychology and behavior as they apply to camera trapping.)

Thursday, August 28, 2008

Student Section Reunion

Last week the redhead and I attended a reunion of folks who long ago were members of a kids' science club at the California Academy of Sciences. The name of the science club was the "Student Section", and that's what it was -- a section of San Francisco's great museum and aquarium reserved for secondary school students. It started in the early 1940s and morphed into the Junior Academy with a more structured program in the 1970s.

The Student Section was a unique educational experience. We paid a dollar a year for membership, and were entitled to Saturday field trips in the bay area, and longer camping trips to the mountains and deserts. If you want to get a flavor of what it was like, read this tribute to one of the academy's late scientists

The Academy didn't archive much material about the Student Section, and now the students are all quite mature, if you know what I mean. So we are compiling testimonies of our experiences for the academy's archives.

Here's what I wrote.

I was about 14 years old when my boyhood friend, Javier Penalosa and I mustered the nerve to walk into the Student Section. Our 4th grade teacher, Mrs. Elizabeth Steinberg, mother of nudribranch specialist Joan “Lefty” Steinberg, had urged us to join the Student Section as soon as we reached junior high school age. Mrs. Steinberg had a contagious interest in the natural world, and her Saturday fieldtrips to Moss Beach at low tide were high adventure. She sent us home with crazy parental-guidance-projects, like boiling and toasting acorns to make acorn mush just like Costanoan Indians.

Until that fateful day, however, Javier and I made almost weekly pilgrimages to the Academy, usually on Saturdays. When the weather was good we walked about 40 city blocks through the park; otherwise we took the #5 Fulton Street bus to 8th avenue.

We were in our element wandering through the academy and copying exhibit signs into our notebooks. The North American Hall was the biggest draw. The dioramas were captivating reminders that wildlife was so near and yet beyond our reach.

We also longed to see the academy behind the scenes. There was only one good excuse -- to deliver a pet snake or lizard for “professional sexing”. San Francisco’s vacant lots and “lands end” had an almost endless supply of garter snakes and alligator lizards, but boy and girl naturalists had no way of knowing their pets’ sex.

We made our sexing requests known to the lady at the information desk, who dutifully called Mr. Slevin on the academy phone. Slevin was the curator of amphibians and reptiles and a veteran of the academy’s famous Galapagos tortoise collecting expedition. Though getting on in years, he was indulgent with small boys. Wearing a green visor, he peered through a magnifying glass at the reptilian cloaca, and then pronounced the sex. Oh yes, he also asked us where we got the creatures. That was it. We thanked him, gawked at the specimen bottles on our way out, and considered it a thrilling experience.

Thus my classmate George Green learned that his pet, a San Francisco garter snake named El Capitan was a male. Tragically, El Capitan was guillotined when the vertically sliding glass door of his cage slipped. But this was another excuse to meet the academy’s staff. We sought advice from the academy’s taxidermist, Mr. Frank Tose, who suggested we make a plaster cast. The two halves of the mold failed to separate. El Capitan was hermetically sealed in a block of plaster. It was not the memento mori we were seeking.

On one of our last visits the old curator apparently decided to take a quick power snooze after we had received permission to proceed to his office. We found him in his rattan recliner with open mouth and hands folded over his chest. Our exit was hasty but quiet.

Then came the Student Section years -- a brief, formative, and unforgettable interlude. Field trips to Californian landscapes became a reality. We met other kids with similar interests. An unidentified specimen was a passport to meet the scientific staff and visit the collection. No longer were we just kids off the street.

I dabbled in entomology and botany, but homeotherms were my true love. I became a regular in the Department of Birds and Mammals. The late Robert T. Orr loaned me Museum Special snap traps, and Mrs Schonewald, his assistant instructed me in keeping field notes and a specimen catalogue. Collecting and preparing specimens became an obsession.
My grandparents had a cottage in the Santa Cruz mountains. When I “got wheels” I ran a “mouse trap line” there all summer and plied Route 9 looking for road kill. When the skinning load was too much to handle, I taught some of the local kids how to prepare study skins. We spent the afternoon at the swimming hole, and set traps after dinner.

At the end of summer I delivered a large box of specimens to the academy. Dr. Orr particularly appreciated the kangaroo rats and shrew moles. A mule skull with canine teeth was also a welcome addition – at the time there was only a female skull in the collection. I beamed.

Perhaps as a result, Orr entrusted me with bat bands from the US Fish & Wildlife Service. Dave Rentz, Ed Kirschbaum and I spent many a happy Saturday night netting and banding bats in the hay paddock of Fleischhaker zoo’s elephant house. Kirschbaum introduced us to quinine water, the man’s drink.

I visited the academy almost every Friday afternoon during my high school and college years at SF State. Dr. Orr chatted with me cordially and the conversation always ended with the same question: “Well Chris, what specimens are you looking at today? To my answer he would reply: “All right, be sure to close the cases when you are finished.” Mrs. Schonewald, his assistant became a kind of mother and confidante away from home. I followed her about as she did her work, and often met Ray Bandar there, who would check in to examine the state of various macerating skulls. It was a lovely community.

The inevitable upshot of all this was that I decided to be biologist. After getting a bachelors degree in biology at SF State College and two summer expeditions to Mt Orizaba, Mexico, I got married and took a masters degree. Then we traveled east to the University of Maryland for the Ph. D. By then live mammals interested me more than taxonomy, and I did my thesis on comparative ethology of a group of small carnivores. In 1972 I headed to Chicago’s Brookfield Zoo for my first job. Two and half years later we moved to the National Zoo’s Conservation & Research Center, in Front Royal, Virginia, where I worked with staff for the next three decades. We developed programs in captive breeding of endangered species, ecological field studies and reproductive physiology, and trained wildlife biology to developing country nationals.

In retirement I entered my second childhood. I am again a boy naturalist, just an old one.

Thursday, August 14, 2008

Coyote shows itself

Rich just sent me the most recent pictures from the mountain. You can call it uncertainty, nervousness, suspicion, or ambivalence. The song dog has seen the camera but still wants to sniff those scats. It lingered long enough for two pictures. It's rangy enough to be a young adult.

The cub was following mama bear. Look at those scats on the ground and compare them between photographs. That cub is a wee little guy.

As far as we know, the creeks on the mountain have run dry. All the same, Rich reports there were no pictures taken at the water hole. He changed the setting for 24 hr shooting instead of night time only. If we don't get pictures next time, there must be other water sources we don't know about. When the weather cools off we'll have to do some exploring.

Monday, August 11, 2008

Chipmunk foresters

We saw plenty of shadow chipmunks (Tamias senex) during the camera trapping course. Between northern California's Eel and Klamath Rivers shadow chipmunks live close to sea level, but in the upper reaches of the Sierra Nevada's Yuba River we found them at 4000 ft. They've been recorded as high as Donner Summit (7089 ft).

This chipmunk shares its range with 8 other species of chipmunks, but its choice of habitat and differences in behavior accords it relative isolation. It is more arboreal than most of its neighboring chipmunks, and often nests in trees. Its name comes from its dark coloration and a preference for shady parts of the forest.

I learned a lot about this species from Craig Fiehler, a participant in the camera trapping workshop who studied the species' seed hoarding habits.

Fifty plus years ago, mammalogist Lloyd Tevis found shadow chipmunks of the Sierra Nevada to be fungus gourmets. Hypogeous (subterranean) fungi were their most common foods from spring to fall, and seeds and arthropods were of secondary importance.

in the Klamath National Forest Craig found shadow chipmunks to be serious feeders of ponderosa pine seeds on 6 experimental plots of thinned and unthinned forest. To study seed hoarding he had to individually number a very large number of seeds, and then treated them with Scandium 46, a gamma-emitting radionuclide with a half life of 84 days. Only then was he was ready to put 10 radiolabelled seeds each in 100 lidless petri dishes in the concentric circles around the trees.

With a low-light level time lapse video camera he filmed the comings and goings of the rodents, and learned that shadow chipmunks literally scarfed up the labeled pine seeds, stuffing their cheek pouches with as many as 100 seeds at a time, and then scampered off to bury them in scatter hoards.

Then he had to use a Geiger counter to find the seed caches.

The rodents revisit their cache sites and eat from 4-12% of the hoarded seeds per day.They also move them to new cache sites.This may seem like a waste of time, but it makes sense if you want to reduce pilferage by your neighbors.

Fooling your neighbors probably plays into other aspects of hoarding behavior. Chipmunks cache seeds at greater distances and in smaller numbers when their populations are high. They bury seeds farther away from trees on unthinned units, and usually in forest openings with a mineral soil substrate. Conditions there are more favorable to germination than in leaf mold and duff. They are seed predators and seed dispersers.

The shadow chipmunk may be a gourmet of fine fungi, but it also seems to be decent forester.


Fiehler, C.M. 2007. Dispersal of ponderosa pine seeds (Pinus ponderosa) by the shadow chipmunk (Tamias senex)in a managed forest. Masters Thesis, Humbolt State University, Arcata, California [pdf here]

Gannon, W.L. and R.B. Forbes. 1995. Tamias senex. Mammalian Species, No. 502:1-6

Sunday, August 10, 2008

Solving a parallax problem

What's wrong with this picture?

It was supposed to be a full frame picture of 4 playful rodents centered in the frame.

Why did I screw up?

The cam was too close, and I misaimed. Taking a little more time might have helped, too.

How can you miss a close-up like this?


The PIR's narrow zone of detection was aimed at the burrow, but the camera was aimed above it. This is one of the problems you encounter when you try to use a camera trap for close-ups. The center of the camera's picture frame and the narrow detection zone of the PIR are not in alignment. It doesn't matter at a greater distance.

Some commercial trail cameras use a built-in laser pointer for aiming the camera; so I just made my own laser pointing device.

This is a snap-on mount made from a hacksaw blade, and a laser pointer with a magnetized base. (They are 'posed' on my table saw). You can adjust the hacksaw blade mount and then move the magnetized laser from the PIR window to the lens window for fine adjustment.

It helps.

Friday, August 8, 2008

Candy crunching coyote

Rich encountered this scat while checking the camera trap line on the mountain. There was more to this coyote scat than the usual hair and bones.

The critter had bolted down a package of Bolitochas Tamarindos, or at least the wrapper, which was pretty much intact. This Mexican confection is described as "tamarind flavored hard candy balls with a chili filling for an extreme burst of flavor".

Where it found the candy is another question. Did some campesino lose his snack to a prowling coyote? Or did the coyote find it in the trash at some construction site?

When Rich checked the cam at the puma scat, there was an image of a female coyote -- possibly the candy snatcher. Though coyote scat is common on the trails, this is our first picture of the species.

Unhappily, the camera had shifted in the case, possibly due to the bear's mischief, and the animal's head was cut off.

Thursday, August 7, 2008

Users of the log bridge

We're back on the mountain in Napa county.

Three more species round out the list of users of the log bridge. Previously, we had striped skunk, gray fox, and Steller's jay. Though recorded from the area, the pileated woodpecker was an unexpected treat.

The log seemed to be off the bear's beaten track, though not far from the camera set at the puma scat.

And a raccoon never comes as a surprise.

Wednesday, August 6, 2008

Fooled by the rattlers

Here's what my camera trapping buddy Rich wrote last week after checking the trap line on the mountain in Napa County.

By way of background, we had set a cam in the "snake pit" on the last visit, and were anticipating some exciting images of rattlers swallowing mice and rats.

It didn't happen. Rich said the snake pit was lacking snakes, and the cam hadn't taken a single picture. It seems they have moved into the old stone lodge.

Here's Rich's email.

"On August 1st I walked into the lodge hallway and was headed for the fireplace room when a loud rattling stopped me dead in my tracks. After a face-off, the snake uncoiled and slithered into the cot storage room, and I went looking for something I could use to pin the rattler without harming it.

"In the storage rooms I spotted a 4 foot length of 3/8 inch wooden doweling and grabbed it up. On my way back to the snake I noticed the doweling had a loop of fine string at one end indicating someone had been noosing lizards with it. Whoever that was, thanks for the use of your tool. I found the rattler hiding behind the vacuum cleaner in a corner of the cot room, noosed it, took a couple photos, and then released it out by the old cesspool "snake pit."

I responded, "Seems like the rattlers moved in the house, huh? Was your grandson with you? Who took the pic?"

"I took the pictures on a tripod."

Codger: "You must have felt like the lone trapper on the mountain. Must have been nice wrestling rattlers."

Rich: "Naw, I don't really relish wrestling rattlers like I did 40 years ago. But they sure are easy compared to things like mambas and cobras, aren't they? Wasn't it nice of the Creator to give them well-defined necks for us naturalists to grab hold of? I think that kind of empathy proves the Creator is a naturalist, and shouldn't it follow that naturalists therefore should be recognized as deities? Tell that to the Redhead.

(Hmmm. Codger's thoughts: Rich knows who's the boss in my house. No way she's going to read that comment. Nice try though. . . . .)

Rich: "Must admit that after getting into it, "wrestling" the rattler was fun, just like most everything else we do in our "work" is fun.

Monday, August 4, 2008

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.

Predator with prey (From the mountain)

Br'er fox nailed a wood rat, and walked past a camera trap before eating it.

It's not common to get a camera trap photo of predation, but that's what Rich Tenaza found this weekend when he checked the cams on the mountain in Napa county.

It would have been nice if wiley fox had faced the camera, but I'm not complaining. We are mighty pleased.

Sunday, August 3, 2008

The camera trapping workshop

Top (left to right): Patrick Kobernus (Coast Range Ecology, SF), Kim Hastings (US Fish & Wildlife Service, Juneau, Alaska), Bill Levinson (Alpha Spectrum Productions, Oakland, CA), Karen Carter (San Bernardino County Museum, California ), Bill Wilson (ret'd, Modesto Junior College, CA),
Bottom (left to right): Craig Fiehler (Endangered Species Recovery Program, Bakersfield, CA), Lisa Ware (National Zoological Park, Washington DC), Chris Wemmer (Codgers Anonymous), Mike Rathbun (San Bernardino County Museum, California), Lorna Dobrovolny (California Fish and Game, Newcastle, CA)

In case you are wondering (or not wondering) what happened at the workshop, well, . . .

most of the 9 participants arrived Sunday afternoon and pitched camp in anonymity. When the mess hall's triangle rang out at 6:00 that evening we assembled for dinner and started to mingle. Afterwards we introduced ourselves formally, and broke the ice by sharing whacky stories (limited to one per participant). Late comers joined us for breakfast the next morning.

The daily routine was to rise in time for breakfast and lunch-making at 7:00AM. After that we met for lectures and discussion. I brought several boxes of gear, books, and eight extra cameras, so the class had ample opportunity to use additional cams and equipment.

After morning lecture on the first two days, we checked my cameras (the ones set a month earlier), and the prizes were aplodon and pine marten. Mike Rathbun and Karen Carter were also rewarded with a marten picture. Apparently the animal made the rounds on Monday night, a full month after I had set my camera.

It was just good fortune that Sacramento Bee writer Mickie Enkoji's research on camera trapping coincided with the course. She and staff photographer Bryan Patrick dropped in on day 1 to see us in action. I failed to get her to reach into an aplodon burrow to appreciate the subterranean microclimate. Nonetheless, the result was a lot of good publicity (2600 blog hits over two days, mind you).

We spent the rest of the week exploring the terrain up and down State routes 49 and 89, making new sets, and discussing results.

Most everyone took off in small groups during the day to set their cams, and some creative sets, like the one below held great promise, but damn if time didn't run out.

My friends Marshall and Kate Reed kindly made arrangements for us to watch northern flying squirrels at a bird feeder on their neighbor's deck. The big-eyed rodents were only 4 feet away so the photo frenzy yielded quite a few full frame shots. Only the codger did it the hard way -- setting a camera trap 12 feet up the tree the next day. Many thanks to the Reeds and Tom & Julie Castro for the consideration.

Wednesday night we called owls. A California spotted owl responded lustily to playback of several different species.

The class was enthusiastic and seemed to be pleased with the experience. Though I harbored ambivalent thoughts beforehand, I'll definitely do it again. In the meantime I am revisiting the area and compiling mammal locations for next year's course.

Here are the species we photographed with our camera traps:



Water shrew (Sorex palustris)
Vagrant shrew (Sorex vagrans)


Long-tailed meadow mouse (Microtus longicaudus)
Brush deer mouse (Peromyscus boylii)
Shadow chipmunk (Tamias senex)
Golden-mantled ground squirrel (Spermophilus lateralis)
Western gray squirrel (Sciurus griseus)
Douglas’s squirrel (Tamiasciurus douglasii)
Northern flying squirrel (Glaucomys sabrinus)
Showtl (Aplodontia rufa californica)


Mule deer (Odocoileus hemionus)


Gray fox (Urocyon cinereoargenteus)
American marten (Martes americana)


Song sparrow (Melospiza melodia)
Dark-eyed junco (Junco hyemalis)
American robin (Turdus migratorius)
Hermit thrush (Catharus guttatus)
Yellow-rumped warbler (female)(Dendroica coronata)

*/ shrew identifications are based on color, relative length of tail, and color of tail, but are not certain.

TOTAL: 13 mammals, 5 birds = 18 species

Many thanks to Lisa Ware for photos of the activities and the flying squirrel.