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.

Tuesday, January 30, 2007

Who killed scrub jay?

The feathers told a story. Last night scrub jay met her demise. On the trail to the camera trap, I found a circle of feathers—blue flight feathers, and a few downy breast feathers. Unmarked, expertly plucked. There was a splash of white—the victim had been killed on the spot. No blood or body parts. Everything had been eaten there, or perhaps carried away.

One thing is certain. The killer was a professional plucker. Cats fastidiously pluck their prey, and I suspect that ringtails do too. Yes, it could have been an owl. Owls may swallow mice whole, but they pluck their feathered prey, though less painstakingly than cats. In their regurgitated pellets bird plumes are twisted among the bones. But I suspect an owl would have carried a dead jay to a perch, and the feathers would have scattered.

This looked to be the handiwork of a bobcat.

As I was hunkered over the evidence, I remembered hearing the jays rallying yesterday. They made a ruckus as I climbed the trail home in the long shadows of late afternoon. It was that irritating cawing of little crows. "Screeep screeep" ad infinitum. Scrub jays indeed have an annoying alarm call. I stopped to catch my breath and locate the noisemakers. I couldn't see them, but they were somewhere in the chaparral on the sunny south slope, perhaps 40 yards away. Was I the cause of their discomfort? Was my presence in the shadows so alarming? Come on, birds, give me a break.

But now, looking at the feathers in disarray, I connected the parts of the puzzle. A resting bobcat saw a man walking through the woods. The man was too close, the cat moved away. A scrub jay saw the cat, and sounded its alarm. Its family mobbed the cat, until it disappeared. The cat returned in the dark, and snatched a jay. It fed on it nearby. The man returned the next morning, and found the jay’s feathers in disarray.

The feathers told a story, and I think, perhaps, I played a bit part in the tale.

Monday, January 29, 2007

No more starry eyes, almost. . .

Have you ever noticed that most night pictures taken with camera traps look flat and the animals’ eyes glow like their brains are on fire? These are two bothersome biproducts of current camera trap technology (among others). They are caused by the camera’s flash, which illuminates the subject head-on. Starry or glowing eyes are caused by a structure associated with the retina. It's called the tapetum lucidum. In dim illumination, when the pupils are dilated, the light from the camera’s flash bounces back from the tapetum. But when artificial light enters the eye at an angle, the reflection is diverted. No starry eyes.

As for flash pictures with the "flat 2-dimensional look", it is simply caused by the lack of shadows when the flash is positioned near the shutter.

A few weeks ago, my friend Ed Gould shared the "fat cat" blog with a professional photographer, who suggested that positioning 2 flash units with slaves to the left and above would give the photos a great deal more depth and improved background lighting.

I dug up an old electronic flash and a slave, and neighbor Richard kindly made me a waterproof mount. A few field trials taught me that the AA cells lasted only a couple of days when the flash was left "on standby". So I wired the flash to an external holder for D cells, which have a much higher mAh rating—and longer battery life.

What I didn’t know was whether the camera flash could be tuned down enough to trigger the slave but not cause eye shine.

I found out last week. Both Zorrilo and Stinkarella visited the "set". For some mysterious reason, Stinkarella's eyes always seem to "burn bright". The creature must be stoked. I think the camera flash would have to be deactivated to circumvent those burning eyes. But I was pleased to find that a few pictures of Zorillo showed off a pair of lovely twinkling skunk-peepers. The problem of starry eyes isn't completely solved, but I'm getting closer. . .

(As for flat pictures, I'll have more to say on that topic when I work out the optimal angle of the external flashes).

Thursday, January 25, 2007

COMMENT: Protein starved killer squirrels

Within hours of posting "California’s gourmet squirrel", an esteemed colleague, Dr Robert Horwich sent this comment to my personal e-mail.


"You ain't seen nothing yet - check this one’r else. And be careful when you are in the woods. A good-sized pack of squirrels will pull you down by your ankles."

Dr Horwich included a forwarded link from the respected BBC. Read it--it reports on a pack of killer squirrels in the Russian Far East alleged to have slain a luckless hound.

Dr Horwich, who could be considered a "squirrel whisperer" was dubious that the squirrels actually attacked and killed the hound "…unless it was near death." He added, "They probably were just gnawing on the body like some of your observations."

Though squirrel bites can be painful, a dog dying of squirrel bites is as likely as a person dying from duck bites. While conceding that truth is sometimes stranger than fiction, my theory is that the three locals reporting the incident had impaired cognitive processes due to vodka.

Wednesday, January 24, 2007

California’s gourmet squirrel

Some years ago my good friend the late and great ornithologist Luis Baptista made a discovery while bird watching during his lunch hour in San Francisco’s Golden Gate Park. There on the park path was a migratory species rarely seen in the bay area. It was flitting about a dead bird, possibly its mate. Luis surmised that the victim had just died of some mishap. As he marveled at his discovery an eastern gray squirrel scampered into the view of his binoculars. To his horror, it seized the dead bird in its furry squirrel-paws and nipped off its beak, which it started to eat like a nut. Luis charged while cursing the squirrel, and retrieved the now beakless bird for science. The value of the specimen was greatly diminished, but the squirrel enjoyed a protein supplement to its normally high carbohydrate diet.

Getting enough protein is a challenge to any mammal whose dietary mainstay is plants, and the easiest way to get a large dose of protein is to eat an animal. This is the dark side of many seemingly harmless vegetarians—they sometimes submit to carnivory. Even the most resolute vegans have been known to lust for a slice of cheese, an omelet, or even a Big Mac, and some actually submit to the urge, usually surreptitiously. On the other hand, bright-eyed and bushy-tailed squirrels have no qualms about eating birds’ eggs and nestlings. And in Canada, the diminutive and boisterous red squirrel is known to occasionally eat snowshoe hare bunnies, which is a rather horrifying thought.

That brings me to the gourmet habits of our princely western gray squirrels. It was October two years ago that I noticed some gnarly swollen twigs with chew marks in the driveway. They were oak galls. California has about 19 species of oak trees, and there are over 150 species of gall wasps that lay their eggs in the leaves and twigs. "Arthritic twigs" and "wood apples" are the oaks’ responses to the irritations of these tiny wasps. But the precision with which the rodent had chiseled out the larvae made one thing clear. The squirrels weren’t eating the galls. They knew exactly where the protein-rich wasp larvae were ensconced in the gall, and they extracted them with the delicacy of a Frenchman forking escargot. It takes a lot of work to make a meal of gall wasp larvae, but in the fall when squirrels are gorging themselves on acorns, maybe the added protein is needed.

This blog was prompted by a 2-year old observation rather than a recent photo, and you, dear reader, are probably wondering what does this have to do with camera trapping? Well, it was an excuse for the codger to use the "tree-hugger", a contraption built by my good neighbor Richard. The "tree hugger" allows me to set the camera trap in trees (which I intend to use for screech owls and cavity nesting birds--so stay tuned).

As for gourmet squirrels, the one seen here wasn’t particularly thrilled with the peanut butter I smeared on the stub. Like a lot of Californians, it probably prefers more exotic sources of protein.

Friday, January 19, 2007

Ringtail's back and groovin' again

In the wee hours of the morning on January 18th ringtail paid a visit to a new camera trap site. The site was a log baited with egg yolk, chicken, and a lump of evil-smelling ground turkey (hidden under leaves--out of sight to ravens and jays). The ringtail visited the log during a three hour and fifteen minute period starting at 3:40 AM. During the 35 minutes it actually spent "on stage" the camera trap took 61 pictures. The animal was active--the average interval between pictures was 21 seconds. These pics reveal a little more about the ringtail’s strange behavior mentioned in the January 8th posting.

3:41:27 AM (photo # 5). It looks like one of the first things it did was scent mark the log. Notice that it is pressing the hips down. (Maybe you don't notice--I admit it's a crumby view). But it looks to me like it is rubbing its backside on the log. I suspect the ringtail has an anal gland or a perineal gland, and this activity leaves a personal "calling card" at the site.

3:52:08 AM (photo # 33). The "dopey phase". Ringtail seems to be "grooving" on the scent. In this transcendental state it seems to be leaning a little to one side.

6:43:20 AM (photo # 53). Now the animal is rubbing its neck on the log--possibly the well-seasoned egg yolk.

6:44:30 AM (photo # 57). Ringtail has seized a piece of egg yolk and is checking it out. I think this proves that egg yolk is a substance of interest.

Ringtail ate the chicken, but left the evil-smelling turkey burger untouched. It doesn't seem to eat the egg--it just makes love to it. In the second photo above, it looks like there is yellow stain on the back of its ears--could it be egg yolk? (Frankly, I'm getting a little bored with ringtail's obsession, and suspect you are too.)

Friday, January 12, 2007

Showdown at Big Rock

Sony s600 and its trusty sidekick Promatic were staked out at Big Rock and ready for the ambush. Though slow on the draw, Sony was ever-vigilant, waiting to shoot any rascal who dared to cross its sights. The loyal Promatic was perched on its gargoyle-like slave, but always followed Sony's lead. Promatic was old and sensitive to moisture. Sealed in a biscotti jar was the only way it could survive the winter.

Unlike these high-tech partners, Zorillo had an unsavory reputation. He was touchy, and he could draw his weapon in an instant. But he lacked Sony’s focus. When he shot it was messy, and there was usually more than one victim.

On the fateful night, Zorillo was ambling through the manzanita when his nose scented chicken. He moved in to check it out. As he climbed Big Rock the scent grew stronger. Suddenly there was a whirring sound behind his back. Even in its rubber-lined Pelican case with the water-proof seal and all that—Sony just can’t prepare to shoot in silence.

Zorillo raised his tail, puckered, and took aim, but it was too late. With a blinding flash of light Sony and Promatic shot first, immortalizing the showdown in a single frame. The fateful day was January 10, 2007. The moment of truth was 4:03:27 hrs.

Postscript—Zorillo decided not to shoot back, and left the scene without touching the chicken dinner.

Monday, January 8, 2007

Egg yolk perfume

Last week neighbor Richard asked if I had any use for boiled egg yolks. "Sure", I said. I hadn't trapped any mice in the garage lately, and I was out of chicken giblets." I'll try them as bait." Which brings me to the subject of deviled egg sandwiches. Back in the Pleistocene, when the codger was a kid, mothers sometimes unwittingly subjected their children to unpleasant experiences in school. In those days it wasn't "uncool" to bring your lunch to school in a lunch box or a paper bag. But deviled egg sandwiches were NOT considered "cool", because they would "stink up the cloak room". Those "stinko kids" were ribbed so badly they begged their mothers never to put another egg sandwich in their lunch bag.

Carnivores of course find many smells interesting and seem to love things that smell nasty. So I sprinkled the crumbled egg yolk in the recesses of the boulder -- the same place the bobcat visited last week.

Two nights later, the ringtail and the skunk smelled the eggs. Ringtail got there first, and spent most of the first 6 minutes hunkered over the eggs in a kind of reverie. Its eyes were closed, and it looked like it was drifting off into dreamland. In other shots it looked like it might be rubbing its cheeks on the rock, that is, scent marking. It deferred to the skunk, who sniffed around for 3 minutes and moved on. But the attraction on the boulder was strong. Five minutes later ringtail was back with the dreamy look.

I'm not sure what's going on. Maybe it had indigestion or just decided to take a nap.

Friday, January 5, 2007

California’s native architect snacks in bed

A couple years ago I had my first encounter with a local dusky-footed wood rat. It took up residence in the shed where I keep garden tools. She was a lovely young female, but not a good housekeeper. I had to pick up hand tools and hardware daily, and then she started to chew up my steel wool. I suspect she was shredding it for her nest. I doubt that EPA condones this material for rat nests. So I live-trapped her and released her in the woods a couple miles away.

The experience stimulated my interest, and I googled up an interesting article. It turns out that dusky-footed wood rats share one particularly lovable quality with people. They love to eat snacks in bed. Not potato chips and ice cream, but more healthy foods, like the leaves of toyon, oak, and bay. Now, one thing our mothers and wives taught us is that eating in bed has sanitation risks. The crumbs can breed fleas. This is especially true for wood rats whose boudoirs are deep within their stick nests, which are seething with insects. So the scientists did an experiment. They reared fleas in mason jars with the rats’ various bedtime snack foods. Low and behold! They found that about 75% of the larval fleas died of exposure to the volatile compounds in bay leaves. The rats don’t actually eat the bay leaves so much as nibble their edges to release the compounds. Toyon and oak on the other hand are the real snacks of the boudoir, but they had no effect on fleas. The dusky footed wood rat actually takes the precaution of fumigating its bed while it snacks. Pretty neat, huh?

When I began bushwhacking paths through the chapparal I discovered a thriving community of wood rats lived only a stone’s throw from the house. They were fair quarry for the camera trap. So here are a few pictures of our tireless bed-snacking architects and their creations. The camera case (9" long) gives you some sense of scale. The small stick nest was started last spring, but construction has been slow. A seedling bay is growing from its base, and the boudoir is probably down the burrow.

Tuesday, January 2, 2007

Fat cat deja vu

A fat bobcat came to this boulder on December 30 at 20:30. The first two pictures were blank--he was lurking about but escaping the camera's shutter. Having noticed "the thing that flashes" he crept up to sniff it--the 3rd picture shows only a brilliant white ear and whiskers at the bottom of the frame. Two and a half minutes later he was back exploring the boulder where I placed some chicken giblets four days earlier. I would guess from its size that this is a fully mature male cat.

I think I have seen this cat before. A year ago on December 4 at 4:45 in the morning a similar looking robust cat walked past a camera beside my house. I've posted last week's picture and the Dec. 2005 picture for comparison. Look carefully and you can see similar spot patterns on the bobcat's breast. (Last year's pic was shot with a 1 mp camera--thus the dull look.)