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, July 31, 2007

Urban Coyotes: Update

The Golden Gate Park coyotes that were shot last week for acting like coyotes were quite possibly parents.

A 5-month-old coyote was hit by a car near that busy stretch of 19th avenue that snakes through the park.

Shortly after the park walker found the carcass he also saw one or possibly two live coyotes of the same size.

The heavy hand of natural selection is again thinning the park's coyote population. Time will tell if the survivor(s) have the right stuff to survive in the city.

I'll keep you posted of any further developments.

Monday, July 30, 2007

Hark, the Mountain Beaver

Hark to the mountain beaver, one of California's most mysterious and best kept secrets. It's not a beaver, and it doesn't live exclusively in the mountains. So . . . you may want to call it by its other name --boomer. Not that that is any better, because they don't "go boom" either.

We should take pride in this lovely, furry muskrat-sized rodent with a stub-tail. It's a living fossil and a unique American mammal. Aplodontia rufa is the only member of its family, the Aplodontiidae. Its ancestral relatives were digging up the Great Plains back in the Late Oligocene and Miocene, and were related to the Mylagaulids, which were more diverse and included the horned gopher -- Ceratogaulus of the Great Plains. That makes the mountain beaver a sole survivor of a once diverse assemblage of rodents.

Until a few weeks ago I knew the species only from the plush furs of museum specimens and the literature. But I always wanted to know the animals in the flesh, so to speak. My chance came this spring when the National Park Service approved my application to do a camera trap survey of wildlife in Point Reyes National Seashore.

The coastal scrub of California seems an unlikely place for mountain beavers. They live in lush conifer-shaded creekside habitats in most of their range, and usually on steep slopes. In addition to the main populations in the Sierra Nevadas and Cascades, California has two small isolated populations at Point Reyes (285 sq. km.) and Point Arena (62 sq. km.). These are in the fog belt of the north coast.

These island populations were obviously connected at some point in the past. As recently as about 3,000 years ago, mountain beavers lived betweeen these two sites. Gnawed bones from Duncan's Point Cave tell us that carnivores were catching them there near the mouth of the Russian River.

During a state-wide distributional survey of mountain beavers, biologist Dale Steele also discovered an even more unlikely habitat in the alkali scrub of Mono Lake. This truly looks like a no-mans-land for mountain beavers, because water limits its distribution. Unlike other rodents, mountain beavers are unable to produce a concentrated urine by resorbing water, because their kidneys lack the loops of Henle which perform this function. They need plenty of free water and succulent vegetation to survive.

Nonetheless, there they are at Mono Lake, pocketed in an oasis with a questionable future. I don't think it is known whether these particular mountain beavers are brave recent colonizers, or old stragglers from earlier and wetter times.

The coastal scrub at Point Reyes on the other hand is sodden during the winter and spring, and fog-bathed in summer and fall. The coastal scrub forms impenetrable thickets of coyote bush, blackberry, Euonymous, poison oak, cow parsnip, and thistle (among others). Here and there deer and elk have blazed trails through the stuff, which brings coyotes and bobcats a little closer to the mountain beavers' inner sanctum. But I got a clear impression that only smaller predators like weasels, skunks, and perhaps gray foxes can penetrate the tangles to the heart of boomerland.

When wildfire burned 5000 acres of Point Reyes's habitat in 1995 wildlife biologist Gary Fellers and co-workers discovered that mountain beavers were more abundant than previously estimated. With home ranges no larger than a half acre and a fairly tolerant disposition, quite a few can pack into an area, but for the most part they are hidden in the thickets.

During 27 camera trap days, the cameras made 858 exposures of which 31% contained animal images. Of the 8 species photographed, mountain beavers were in only 7% of the photos, and most of them looked like this.

I am not satisfied. I want a full-body shot worthy of a centerfold. Clearly I need more time to catch the boomer disporting itself out of its burrow.

Many thanks for the cooperation of Point Reyes National Seashore, National Park Service. I am grateful for the assistance of Drs Ben Becker (NPS) and Gary Fellers (USGS).

Beier, P. 1989. Use of habitat by mountain beaver in the Sierra Nevada. Journal of Wildlife Management, 53(3):649-54.

Carraway, L.N. and B.J. Verts. 1993. Aplodontia rufa. Mammalian Species, No. 421, 1-10.

Fellers, G.M, D. Pratt, and J.L. Griffin. 2004. Fire effects on the Point Reyes Mountain Beaver at Point Reyes National Seashore, California. Journal of Wildlife Management, 68:503-508.

Martin, P. 1971. Movements and activities of the mountain beaver (Aplodontia rufa). Journal of Mammalogy 52(

Steele, D. T. 1974. An ecological survey of endemic mountain beavers (Aplodontia rufa) in California (1973-83). State of California, The Resources Agency, Department of Fish and Game. 51 pp. (pdf)

Steele, Dale. Mountain Beaver (Aplodontia rufa) Journal

Wake, T.A. 2006. Archaeological sewellel (Aplodontia rufa) remains from Duncan's Point Cave, Sonoma County, California. Journal of Mammalogy 87(1):139-147.

Friday, July 27, 2007

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.

Tuesday, July 24, 2007

An appreciation of wrens

Bewick's wren was the least expected and smallest of the tunnel's visitors. What poetic justice if it were only a member of the genus Troglodytes (the cave dweller). But that's not the case. Troglodytes is a scientific name reserved for the even smaller house wren and its Old and New World relatives.

I encountered the species last summer when a pair took up residence near the potting shed. The male was a respectable songster who crooned exuberantly from a Photinia hedge next to the garage. Believe it or not, I haven't found a recording on the web that can equal this particular bird's singing. Apparently, there's a lot of individual variation in song. Anyway, they hung around until late fall and then disappeared. It was disappointing they didn't show up this year, but it's good to know there are a few down in the ravine.

Howard Ensign Evan's book, "Pioneer Naturalists" tells us that Audubon named this wren after Thomas Bewick (1753-1828), an engraver who authored "A history of British Birds". It was a kind gesture, but I think the German name "Zaunkoenig", or "hedge king" is a far more appropriate moniker for wrens. Hedge Kings rule the thickets, and it's a treat to see one at close range. German appreciation of the wren's diminutive short-winged body plan inspired the naming of the LF-1 Zaunkoenig. It was a curiosity of aeronautical design -- a little, slow-flying barn stormer kind of plane capable of very short takeoffs and landings.

When it comes to defending territory wrens in general are "butt-kickers", and the house wren is a grim eviction agent. I'll never forget the Saturday afternoon I was "taking the airs" on the back porch in northern Virginia. I had been reading and watching dogfighting carpenter bees in front of the garage, when something fluttering in the martin house caught my eye. It was a house wren.

The martens had long since abandoned the metal contraption next to the vegetable garden, and house sparrows were the present occupants. The wren flapped its wings and struggled in the entrance of a nest chamber in an alarming way, making me think it had been snagged by a lurking blacknake. But then it popped out of the nest hole and "what the hell?!" -- it tried to fly off with a nestling hanging from its beak!

The nestling was nearly the size of the wren, and the flight trajectory portended a crash landing. Downward they went for a few feet, before the wren released the chick. I was agog. It was back at it in no time, and a few minutes later it had finished the job. There were three pin-feathered chicks on the ground. Horrors!

Now this, I thought, was an unusual observation, so I eagerly shared it with my National Zoo colleague, Gene Morton. Gene is a highly respected ornithologist and wren enthusiast, who periodically honored me by asking for a status report about the Carolina and house wrens that lived around our house.

Well, the observation didn't exactly get him hopping. He acknowledged that house wrens were famous for this kind of thing, and that they don't hesitate to evict nestling chickadees, titmice and tree swallows. They destroy their eggs too. It's not that they are vigilantes who systematically oust all cavity nesting dickeybirds, but they like to keep several potential nesting sites vacant. It's an inducement to hen wrens. Many of them are practicing polygamists.

We also had a resident population of Carolina wrens in northern Virginia. They often visited the windows of my home office and cocked their heads while searching the spider webs. In our 30 years of residence there were a few severe winters that starved out "the Carolinas". A year or two would pass before we would again hear their familiar song ("tea kettle tea kettle tea kettle").

Sunday, July 22, 2007

On river rovers and camp raiders

You're looking at a true river rover. This raccoon plys the river banks and shallows in the summer. It doesn't depend on people for food, though it won't hesitate to feast on their leavings -- fish guts, unused bait, and junk food. Its usual diet is revealed in its scat -- crayfish and aquatic insects, with occasional frogs and fish. In the winter and spring, when the creeks are in spate, I imagine it works the uplands for food.

That raccoon came to a set I made on a cobble bar in Butte Creek, a couple miles from my house. It's down there behind the boulder in that patch of willows near the left hand bank.

The only human habitation in the area was a "California fixer-upper" tucked in a gulch between the PG&E flume and the creek. Finding prime riverfront property for a bargain $999,999 was an unexpected surprise.

Okay okay, I'm pulling your leg. It was an abandoned miner's shack. There's a spillgate on the flume up the hill from the shack, and a sign intended for latter day sourdoughs, hikers, and codgers like me. It informs you that the gulch below the flume could flood from diverted water at any moment and without warning. (So much for gold miners and common sense.)

The prospect of a deluge didn't worry me either, but the presence of miners would have sent me packing. The beer cans however were old, so I knew they hadn't been around for a few years.

I climbed down to the creek, found the cobble bar, and put a tablespoon of "predator stink" on a rock, thinking a family of otters would show. No such luck. Six days passed before the coon waded out to explore the smelly rock. It sniffed it and was gone in 23 seconds. I got 4 rather disappointing pictures.

Raccoons are comfortable city and town dwellers, which may explain why they don't visit my camera traps. Why wander the chaparral and ravines for slim pickings when the neighborhood offers a smorgasbord? The two settings breed different kinds of animals--the trim retiring river rover you see here, and brash rotund coons of city, town, and campground.

Back in the 80s we had an amusing experience with Minnesota's camp raiding coons. It was late August and we were on the long trip home from Glacier National Park. The girls and I had just pitched our tents in Itasca State Park, and the redhead was dutifully starting dinner. Our rations were low. I had been advised to stop at a grocery store, but we were "in the boonies", and none turned up.

My wife didn't buy my feeble excuse, ("I guess Norwegian bachelor farmers grow everything they eat."). I was informed that men couldn't take directions, and as a consequence we would be eating leftovers.

Normally this wouldn't be bad news. The redhead is a gifted chef. But we were down to a plastic bag of limp carrots and a can of refried beans. As she scraped black spots from the carrots, my daughters protested, "Mo'om!".

Then the wonderful aroma of barbecued chicken wafted into our camp.

"You know, sweetie, one of these times we should splurge and buy some chicken or steaks. These Minnesotans know how to do it up right." It was a wistful thought, and the girls chimed in their endorsement.

As we basked in the bouquet of sizzling chicken, and forlornly anticipated our own humble meal a great howl of pathos rose from the neighboring campsite.

I mosied over to find 4 large raccoons on the picnic table amidst a mouthwatering repast of barbecued chicken and corn. Grandma and mom were unceremoniously crawling into their tent and commanding the kids to "Chase them away".

"We can't", answered big brother who was about 12 years old. "They're too big."

As the coons feasted, the brother and his two younger sisters gave a blow-by-blow account. They were just like sportscasters, and the ladies lamented each call.

"They finished the chicken, mom."

"Oh, my God." came the voices from the tent.

"Grandma, they're eating your cake!"

"Oh, my God," they grieved again, "not the cake!"

And so it went.

Shortly after the drama ended we ate our refried beans and limp carrot sticks, and the raccoons ignored us completely.

"You know, there's something to be said for keeping it simple," I mused.

The redhead remained silent.

Friday, July 20, 2007

Urban coyotes

There was a flap in San Francisco last week. A pair of coyotes living in Golden Gate Park had a territorial dispute with a couple of leashed Rhodesian Ridgebacks. The authorities decided there was a clear and present danger to pets, and the two coyotes were shot. There was a hue and cry from both sides of the fence, but coyote sympathizers seem to be in the majority.

Coyotes have been reclaiming parts of San Francisco for several years now. They trickle in from the thick coastal scrub south of the city in the San Bruno Hills and San Mateo County where they have always lived. Wildlife biologists estimate there are less than a dozen urban coyotes in the city. The best coyote habitat is Land's End -- the steep cliffy area beyond the Golden Gate. The Presidio, McLaren Park, Lake Merced, and Bernal Heights also have their wild patches and a few coyotes too.

More recently at least one pair of coyotes took up residence in Golden Gate Park. The park has plenty of food. There has always been a bountiful population of brush rabbits and pocket gophers, and the house mice used to breed by the bushel when the mounted police composted hay from the horse stables. It also has a lot of people

Until now the coyotes have been good citizens. Though they were frequently spotted by park visitors, they kept a low profile, didn't sing, and fed on local game. But apparently they became fed up with canine intruders. A steady procession of bizarre-looking dogs visited the park with their owners. Some looked like food, some looked like rivals. To the coyotes they were fair game.

The ill-fated pair was most intimidated by the Rhodesian Ridgebacks. They were three times bigger than themselves, and they stirred the purest of canine emotions -- deep passionate blood red aggression. So they attacked the ridgebacks. The melee was just a dogfight, but it freaked out the owner and injured one of the dogs. (It needed stitches) The next day (last Sunday) a dog walker showed up on their turf with two Jack Russell terriers and 2 bigger dogs. The coyotes showed "culinary interest" in the Jack Russells, but the bigger dogs chased them off.

The die was cast. That night the authorities (USDA Animal Control specialists) lured them in with a predator call, and shot them with "a small hunting rifle".

Officials observed that coyotes are normally retiring around people, and that such bold conduct is uncharacteristic.

This is true, but these coyotes couldn't really get away from people, could they? If they didn't adjust to people, they would have stressed out and lost it. If a muni bus didn't get them first, they would have died with adrenal glands the size of tennis balls.

The problem is this: the songdogs had flouted a cardinal rule. "Always keep your distance from people and their pets. The pooch may look like food, but don't go there. And don't eat garbage. It may smell good, and it may be easier to find, but gophers and rabbits are better for you.

"Remember that human society is hard to fathom. Dogs may fight each other, chase cats, bark at the moon, and eat garbage, but don't kid yourself. You are not that kind of dog. For you the rules are different.

And nature lovers, there is a message here for you too. You may have and enjoy your urban "yotes" as long as they live by the rules. Even in the great city of St. Francis, bad coyotes must die so good coyotes may live.

It's part of the evolutionary play. In a few decades, your grandchildren will feed urban coyotes just like the pigeons at Union Square. By then they may even do a few tricks for a handout.

As for me, I'll take the wild coyotes with all their faults.

Monday, July 16, 2007

Incurable bone chewers

That moose antler was a gift from my older daughter. It was already weathered and chewed by a porcupine when a grad student found it in northern Minnesota. My daughter bugged the grad student until he gave it to her, and then she shipped it to me in Virginia. It arrived in a very large box. A gift for a goofy dad. Yes, biologists are a little weird.

I made this cool sign out of it, and I liked it a lot, so when we moved to California I hauled it along.

It's a bone of contention. Every now and then the redhead discovers some useless but sentimental thing that I saved from the past (like the antler), and gently reminds me that she jettisoned all kinds of useful things when we packed off to California.

My daughters and I respond to these observations the same way.

"You married me (him). You knew what I (he) was like. I (he) can't help it. Biologists are a little weird."

Her point of course is well taken, a gentle reminder of the tolerance and sacrifices of a biologist's spouse.

Well, back to the story. It didn't take long for the squirrels to discover my eponymous moose antler, and we developed a routine. I hear the unmistakable sound of rodent gnawing antler, stop what I am doing, sneak around the garage, and suddenly but quietly make my appearance.

The squirrel stops gnawing, but doesn't flee.

"What in the hell do you think you're doing?!"

It hesitates and looks at me bug-eyed, and then discretely makes off into the canopy.

"That's more like it!" I continue. "And kindly leave my damn moose antler alone!"

It's all false bravado, of course. I actually don't mind them eating the antler.

The fact of the matter is that rodents are incurable bone chewers, and antlers are just bones, though very special ones. Hardly anything, except metastatic cancer grows as fast as deer antlers in velvet. When the growth is complete the cartilage is thoroughly embedded with calcium, phosphorus and various trace elements, and as the velvet peels the buck, stag or bull undergoes a personality change. It's a hormonal thing. Testosterone, the evil hormone that confuses rational thought transforms relatively docile velvet-antlered male deer into aggressive, anorexic, sex-crazed hard-antlered fiends.

In due course, the deer that survive the hunt shed their proud adornments and their sex-vanity, and the antlers lie there in the snow or on the damp duff.

Then come the "antler collectors" and the antler eaters. Antlers are worth money these days, and a lot of antler or shed collectors are good capitalists. They want to beat the competition. They also know that if they wait too long, the rodents will start to eat the antlers, and diminish their value. So they like to start looking early, and this can be a problem. When people are wandering around the woods in the dead of winter and deer are living on hard times it can put the deer at a disadvantage.

On the other hand, the shed eaters -- mainly rodents and rabbits are just responding to their physiological needs. They're capitalizing on a concentrated source of calcium and other minerals found in bone. Only a small percentage of the calcium in the mammalian skeleton is dissolvable and can be accessed for fetal growth, lactation, and the unending growth of the incisor teeth. So external sources of calcium are important. Calcium is an abundant element, but it's a lot easier for a rodent to gnaw a bone that chew limestone.

My casual observations of bone-gnawing squirrels suggest that it occurs year round. Consider this a hypothesis. I assume that the demand for calcium for the ever-growing incisor teeth is more or less constant, and assume that bone-gnawing is also a continuous habit. Who's going to do the experiment? Or who's going to direct me to the published results? So many questions!

Meanwhile, this old fool watches his moose antler slowly shrink, and verbally abuses the squirrels who come and go and help themselves. Yes, biologists are a little weird, but we're harmless, sometimes lovable, and we sure know how to have fun.

Thursday, July 12, 2007

Unexpected lady with a scar

Sometimes you get "species y", when you are targeting "species x".

I haven't seen a ringtail since the winter, but when I found this outcrop on a very steep slope I heard a voice saying, "Bassariscus astutus . . . Bassariscus astutus" (That's the scientific name for the ringtail). It's that time of year when little ringtails should be accompanying their moms, just like spotted skunklets. That's what I was hoping for.

Even though I used castoreum and cooked egg yolk, the ringtails didn't show, but there were plenty of shots of wood rats, deer mice, Steller jays and spotted skunks. And I got two pictures of this puma. She came on July 4th at 8:03 AM.

The camera was too close for a full length body shot, but this is the sharpest puma shot I have taken. You can count her whiskers.

What? You say you can't count her whiskers? Well, tell me this. Do you see a dark marking on the inside of the hind leg, just below the belly? I think it's a battle scar, a scrape that is almost healed. If I am right, my next guess is that it was inflicted by a struggling black-tailed deer.

Okay, I can hear the comments ("Where does he comes up with that crap?")

Well, let me ask you this. Have you ever tried to wrestle an adult deer to the ground?

My colleague Jim Dietz and I used to take turns wrestling white-tailed deer caught in a clover trap. This wasn't for recreation or exercise. We were capturing, marking and releasing deer so we could estimate population size.

We didn't have a collapsible clover trap that allowed us to topple the deer. Ours had a rigid frame, so we had to go into the trap WITH the deer.

This required the psychological preparation and concentration that you see in bronco riders before the gate swings open.
You pull your cap down to your ears, punch yourself, and blink hard. Then you take a deep breath ("the signal"), and your buddy pulls the door up so you can dive into the trap and get beat up.

The proper technique was to kind of mount the deer very quickly and bear down with your weight, so it collapsed beneath you with its hind legs extended. Then your buddy joined you, and threw a bag over the deer's head, which had a calming effect. We restrained them only briefly to take a few measurements. Then we pulled an identification collar over their necks. and released them. It was over.

The mental preparation didn't seem to make much difference, because the bedlam in the trap was in high-speed animation. You never forget the piston-power of those hindlegs. They tear your jeans, hoof-strafe your body, and kick the snot out of you. Though we were relatively young, neither of us ever cried, "Crikey mate! I wish I could do THAT again!"

With practice the puma dispatches the black-tailed deer and only gets a little roughed up. But every now and then it probably takes a hoof to the body, and that's what I think happened to this lady cat.

Tuesday, July 10, 2007

Spotted skunklets


The skunklets have arrived with their mothers.

Sorry I can't offer a better family portrait, but these little skunks don't stay put. Mom is on the rock, and one of the three skunklets is out of sight.

Out of 60 images, only a couple of shots show them horsing around.

So they are not the best subjects for camera traps. Still, it's newsworthy from the standpoint of natural history.

The cams started to get baby images on June 25th, and I am sure I have 2 families -- one has four skunklets, and the other has three.

They are about three quarters adult size now. As far as I know, Wilfred Crabb's study of spotted skunks, published 63 years ago, is still the main reference on body growth. When I compared these youngsters to his photos of developing skunks, I concluded they are about 2 and a half months old. That would put their birth in mid to late April.

When Crabb studied his spotted skunks in Iowa, it was believed that there was one species. Then Rodney Mead discovered that western and eastern populations of spotted skunks differed greatly in gestation period or length of pregnancy. He discovered that the very prolonged gestation of western spotted skunks -- about 7 to 8 months-- was due to delayed implantation.

In most mammals the early embryonic stage known as the blastocyst implants itself in the wall of the uterus and continues development. In delayed implantation the embryo floats about in the uterus in suspended animation so to speak. It simply stops developing until it implants at a later date.

Mead found that the eastern populations have a relatively short pregnancy of 50-65 days, and delayed implantation lasts only two-weeks. These findings prompted a re-examination of the spotted skunk's taxonomy, and the former species, Spilogale putorius, was divided into the western species, gracilis, and the eastern species, putorius.

The photos of mother and young tell me that these skunks are probably at the very end of that contentious period of mammalian development called weaning conflict. That is when the youngsters are shifting from a diet of mother's milk to solids. Mother increasingly rejects their attempts to suckle, and the offspring become brazen and insistent. Mom gets stingier with her milk, and in the end the youngsters are forced to eat solid "grown-up food". It's one of those painful experiences of growing up.

The redhead and I witnessed this phenomenon in our daughter and grandchildren. We were amazed at the relentless will of the child who wants breast milk, especially after polishing off a peanut butter sandwich. Forget about clever excuses, rational explanations, and attempts at distraction. They don't work.

The child knows one thing which it sums up in a boisterous demand. "ME ME MILK!"

The name of the game is obvious, to convince the parent that failure to suckle will have dire consequences. And it does. Their crankiness drives you crazy.

Thus we coined the term "crankinpuss" -- the child with the sour expression because it didn't get its way.

"Are you a crankinpuss today?" (softly and sweetly said)

"I'M NOT A CRANKINPUSS. I WANT ME ME MILK." (in a very loud voice)

As I said, I think the skunklets have passed the crankinpuss stage. They seem to be having a lot of fun exploring the world.


Crabb, W.D. 1944. Growth, development, and seasonal weights of spotted skunks. Journal of Mammalogy 25(3):213-221.

Mead, R.A. 1967. Age determination in the spotted skunk. Journal of Mammalogy, 48:606-616.

Mead, R.A. 1968. Reproduction in eastern forms of the spotted skunk (genus Spilogale). Journal of Zoology, 156:119-136.

Mead, R.A. 1968. Reproduction in western forms of the spotted skunk (genus Spilogale). Journal of Mammalogy, 49:373-390.

van Gelder, R.G. 1959. A taxonomic revision of the spotted skunks (genus Spilogale). Bulletin of the American Museum of Natural History, 117:229-392.

Verts, B.J., L.N. Carraway, and A. Kinlaw. 2001. Spilogale gracilis. Mammalian Species, No. 674: 1-10.

Kinlaw, A. 1995. Spilogale putorius. Mammalian Species, No. 511: 1-7.

Monday, July 9, 2007

Bare-bottomed bear performs

All day long the scent of beaver castoreum wafted upslope, and every night, as the FurFindr wailed pitifully, it wafted downslope . Nothing came for a month. The camera sat there and took two daytime pictures of the rock. False triggers from a puff of warm air. No bird, no squirrel, no nothing!

I was starting to think this was a "dead set", but I wasn't ready to give up.

I removed the FurFindr and deployed it at a new set at the tunnel, and I baited the rock with boiled egg yolk.

Two days later a bear came, but it was interested only in the camera. It took 5 pictures of itself trying to abuse it, and after 43 seconds gave up. The spiked protector discouraged it sufficiently that it paid no attention to the rock. No doubt something, undetected by the sensor, had eaten the egg yolk. Maybe millipedes in the dead of night.

Three days passed and then at 7:00 in the morning a mountain lion mounted the rock. It was there for 15 seconds. I got 2 pictures.

Four days later and the bear was back. It paid the camera a brief visit.

Then it went to the rock. It was a bare-bottomed female (I believe this is Scruffy's mom), and she seemed familiar with the surroundings.

The Furfindr had been gone for two weeks, so why is she looking up at the limbs overhead? Had she visited the rock before, undetected by the infra-red sensor? She sure seems to be looking to where it used to hang.

Friday, July 6, 2007

Last portrait at mossy rock

In seven months this is the only bobcat that visited the mossy rock -- at least when the camera was in operation. It passed by a week ago at 2:50 AM. That raised my species count at the mossy rock to 19.

It is the fifth bobcat I have captured with camera trap over a period of 32 months. As I mentioned before, I think the pumas may keep their numbers in check.

My new neighbors, who now own the mossy rock and this 12 acre parcel, and who will soon build a house, did a little bushwhacking on their property. I captured their images at another camera trap near the mossy rock, and decided to pull the two cameras until I meet them, and receive official permission to camera trap there.

Meanwhile, I am working myself up to make the long trek into the canyon where I'll make a creekside set. I have been accused of acting like "mad dogs and Englishmen" before, but I'd prefer to do this AFTER the temperature drops below the 100s.

Wednesday, July 4, 2007

Visitors in tunnel vision

Four hours after I left the set, a wood rat climbed into the tunnel and triggered three pictures, only one of which contained its out-of-focus image. The visit was brief, to check out the new smells.

Then Scruffy showed up the next afternoon at 16:23. She approached from the west side, peered into the tunnel, climbed in and sniffed the corners where the mice were cached. The camera took 9 photos in the space of a minute, but none recorded her eating the mice or sniffing the scent. And then a surprise. . .she actually turned around in the tunnel to make her exit.

The camera waited.

Two hours later she was back again, peering into the tunnel wearing alert ears.

Does this picture stir your genetic memory? Can you imagine sitting around a fire in a cave? Bloated with meat and sucking marrow from a bone. . . when . . . there's a shuffle of leathery paws, and suddenly that bear silhouette is there at the end of the tunnel? Waaaaahh!

This time she passed through the tunnel from end to end, taking seven pictures in about 30 seconds.

At the end of her passage she squeezed past the camera.

The final picture is of an out-of-focus paw. Scruffy is a gentle bear. If she touched the camera it was hesitant and meek.

I confess that I am very pleased with these pictures. But there were more. The woodrat paid a morning visit in daylight, and then a family of four spotted skunks made three appearances yielding 20 photos.

How interesting it would have been to see those skunks milling about, but the pictures weren't in focus. The camera seems to focus on the trees beyond the tunnel unless a furry body is dead center in the frame. I didn't figure this out till I examined the pictures on the computer screen.

I want pictures of baby skunks!

I left the camera for another round, using egg yolks as bait, but I can only expect more of the same blurry images, unless something big climbs into the tunnel and fills the space like a cave bear.

Monday, July 2, 2007

A camera trap with tunnel vision

In one of the ravines not far from here there's an outcropping that has a short tunnel through it. This outcropping is actually a moss covered pinnacle of a soft gray-colored stone, and I'm not sure whether the tunnel is a natural formation, or resulted from miners playing with dynamite a hundred or more years ago.

For a couple months I've wondered if the tunnel would make a decent set for a camera trap. My idea was to place the camera at one end of the tunnel and then try to lure critters to the camera from the other end. It might make an unusual picture.

I hadn't visited the site since late winter, so I made a brief recce to convince myself it was feasible.

It was, but I might have to make two trips to get the set ready. The limiting factor would be finding a place to anchor a steel post for the camera mount. If I couldn't set a post, I might have to juryrig a camera mount that could be set right in the tunnel. That would require an appropriate length of pipe with a strong compression spring to hold it in place. If you don't know what I'm talking about maybe you have seen a spring-loaded pull-up bar in a door jam. That's the idea. I'd have to mount the camera in the middle of it.

A week later I packed my rucksack, filled the water bottle, "pre-hydrated" by guzzling Gatorade, and sprayed myself with insect repellent.

In about 40 minutes I arrived at the new set (# 62 -- yeah, I keep a register of camera trap sets).

Wonderful! On the East (uphill) side of the tunnel there was a crack in the rock base. I drove in the 2 foot length of steel post with a hand sledge. It fit as snug as a bug in a rug. It would take a Herculean effort for me to extract it, but it was comforting to know that even a bear with the strength of Arnold Schwartzneggar would have trouble tearing it loose.

I mounted the camera on the pipe, tightened the mounting screw and stood there admiring my handiwork. Something was missing and I started to curse. I had forgotten to pack the bear protector -- the spiked frame for the camera case. A cantankerous bear could still chew it up even if the post was anchored in cement. Forget about it, I told myself. You can fix it next week.

A few words about my plan. If small mammals visited the site, it didn't matter which end of the tunnel then entered. There was enough space inside for them to turn around. But if a bear or mountain lion came, I wanted it to enter facing the camera. That means I had to attract them from the west side.

I climbed to the top of the pinnacle and suspended the FurFindr (a digital recording of a squalling rabbit) from a tree limb about 6 feet above the tunnel's west side. I switched it on; the rabbit squalled twice. It was now ready to start at sun set. Then I tucked two dead mice into crevices in the middle of the tunnel, and dabbed castoreum between them.

If the plan works, the predator will hear the squalling rabbit from the downhill (west) side. If it comes from the east, it will hopefully move to the downhill side where the sound is loudest. Then it will pick up the scent coming from the tunnel, because breezes move downhill at night. Next, it will look in the tunnel, and if all works well, it will crawl partially inside to snort beaver scent and eat mice.

I switched on the power, climbed around the rock to the other side, and did the "walk test". The red light on the passive infra-red sensor blinked whenever I moved. A minute later it blinked 5 times, and the lens extended.

The set was ready.

[Stay tuned: In the next post you will learn who is dumb enough to go into the tunnel.]