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, May 28, 2010

A peaceful pubescent hooter

Last week was rendezvous at Chimineas.

It takes a grueling 7 hours, mostly on depressing Interstate-5 to get there, and if any of you remember the Carol Burnett show and Tim Conway's rendition of The Geriatric Fireman, well that's what I looked like when we arrived and I unloaded the car.

In a few minutes the scenery and a scolding kingbird were magically restoring me, and I paused to look up into the cottonwood next to the ranch house.

About 40 feet up there is a tangle of sticks, and six weeks ago it was crowned with the ear tufts of an incubating Great Horned she-owl.

When the wind tossed the branches, she would rise up majestically and peer out like an inscrutable Ahab weathering the storm.

On this visit I was expecting to see a lot of owl traffic and one or two pubescent hooters, but when I binocularized the nest it was empty. 

How could it be? If my calculations were right the youngsters should have been "branchers" by now.

Craig said the owls were delivering cottontails to the nest last week, but evidently they had flown the nest.  Damn!

This abrupt departure was a bit irritating, but not out of character.

The owls had denied me other pleasures of my second childhood. Though I have searched beneath their nest and neighboring trees I never found a single owl pellet or discarded bits of rabbit anatomy.

But I am grateful that the hooters nested smack in the middle of ranch headquarters, which is an oasis for cottontails and songbirds.

Cliff swallows under the eaves of the ranch house.

Tractor, ATV and car traffic didn't affect them, and their hooting has lulled me to sleep.

Nesting horned owls are forbearing birds.

Some 80 years ago a soldier by the name of L.L. Gardner found a horned owl nest at Fort Riley, Kansas.

Though the nest was 43 feet up a hickory tree Gardner could see everything from the rimrock above, and made regular observations until, in Garner's words . . .

"Two soldiers casually riding by on horseback along the rim rock espied the young now grown large and bold and sitting up prominently on the nest.

"One of them ascended the tree, threw one of the Owls to the ground, tore the nest out of the tree and carried the other fledgling down clinging to his coat sleeve.

"Having photographed the pair they were about to dispatch them, when by an extraordinarily fortuitous chance the only other officer, Major C.C. Hillman, to whom I had shown the nest, rode by and rescued them.

"He brought them in to me and I hastened out to the tree nest in an effort to rehabilitate the family."

The nest was beyond repair, so Gardner located a large hawk's nest nearby, bundled it with cord and lashed it into the owls' nest tree.

"During this time the two nestlings sat on the ground beneath the tree and watched the entire procedure interestedly with their great yellow orbs fastened on the nest.  Occasionally they stretched their wings in a contented manner or walked around slowly."

"There was no protest on the rough passage up but immediately on being replaced in their new home rewarded this kindness by thankless hissing and aggressive hostility."

That night the parents visited the ersatz eyrie and fed the young, but they disposed of the dry grass with which Gardner had caringly crafted the nest.

So where did these pictures of the pubescent hooter come from?

At the end of the third day of fieldwork we rolled up to the ranch house, and RandomTruth spotted the young owl roosting peacefully.

We rushed for our cameras and looked like crazed paparazzi, but the bird was as serene as a monk. 


Fitch, H.S. 1947. Predation by owls in the Sierran foothills of California. Condor, 49:137-151.

Gardner, L.L. 1929. The nesting of the Great Horned Owl. The Auk, 46:58-69. 

Wednesday, May 26, 2010

Fred remembers Rattler

Fred perked up and sniffed the air vents as we approached Chimineas.

It was warm, slightly overcast, and breezy as we cruised San Diego Creek Rd toward the ranch gate.

And there it was in the middle of the road, a two-foot rattlesnake.

I had obsessed about the risks to my exuberant hound ever since Craig told me last week that the rattlers were back and popping up everywhere.

Fred had his rattlesnake vaccination a couple months ago, but I was still concerned about his high jinks in the sage where rattlers lie in wait.

This was a chance to test his memory.

I opened the car door, hooked him by the collar and led him the snake, which snapped into a sigmoid coil and rattled.

Before I could shout "NO!" Fred cowered and pulled me back towards the car.

I think he might have remembered his last lesson.

I am happy to report that in the three and a half days of Chimineas adventures that followed Fred encountered no rattlers -- at least none that I know of.

Wednesday, May 19, 2010

Hard nuts to crack

I always forget to kick the pine cones out of the way before I engage in the most strenuous but gratifying of male Freudian rituals: vernal weed whacking.

The wicked looking cones I am speaking of drop like small bombs from the gray (formerly digger) pines (Pinus sabiniana), -- the familiar California endemic that sparsely cloaks the dry slopes of the inner coastal range and Sierra Nevada foothills.

To add insult to injury each spine comes with a blob of pitch.

You won't find a single one in Nevada or Oregon, and they're manna to the western gray squirrel.

Anyway, as I kicked a cone out of the way a large seed popped out and my foraging instinct kicked in.

These nuts, I observed, are bigger than the pignoli the Redhead buys in the market and toasts for salads and pastas.  And if your time isn't worth money they're much cheaper too.

An hour later I was drained by the grueling rite of spring but had sufficient reserves to go back and gather the errant cones which I set beside the garage for solar toasting.

By week's end the thorny scales had opened and relinquished their bounty -- a fistful of nuts the color of roasted coffee beans.

It was time to work on the cones, and I was soon caught-up in knocking their nuts loose.

In my gnarly grip the hooked thorns broke off on the pavement, but I was not spared the pine cone's other revenge -- gummy fingers.

I can sympathize with the squirrels with pitch besmirched cheeks.

Pine nuts are hard to crack, but it doesn't take much to work out a system.

A small bench vice worked better for me than a snub-nosed pliers.

With a turn of the screw you can control the compressive force of the jaws much better.

I cracked 159 nuts and found that 38% were shriveled duds.

I have enough however to garnish our salads next week when the camera trappers rendezvous at the Chimineas Ranch.

PS: Fred the squirrel impersonator and guess who got in trouble 
when someone rubbed his pitch-dabbed cheeks on the carpet. 

Thursday, May 13, 2010

Light-headed leporids that run like hell

"My, what large ears you have" 

Why are jackrabbits so awesomely charismatic?

What?  You think I'm pulling your leg?

Then you haven't seen a jackrabbit skipping across the prairie like a tumbleweed in a storm.

I'm telling you Jack is a superb runner, and a running Jack is a sublime sight.

He can't bluff his predators, can't blast them with vile chemicals and can't impale them with quills.

Jack's survival depends on speed. It's his main defense against ambushers and fleet-footed coursers.

His tribe -- the leporids -- are natural runners, and those species that have been clocked are about 4 times faster than rodents of the same size.

But among the leporids jackrabbits are the ultimate sprinters.

A black-tailed jackrabbit can crank it up to about 70 km/hr  (or 44 mph), while a coyote, several magnitudes larger, does about 65 km/h (or 40 mph).

Watching a jackrabbit in overdrive is a thrill, and scaring one up from its hideout is also a thrill, though you may have to change your pants when your blood pressure returns to normal.

They can afford to bolt at the last minute because they're faster than you.

Plus, an explosive exit may momentarily startle a predator and give Jack a head start.

If there's a high speed chase rabbits are capable of stunning gymnastic maneuvers.

I once saw some amazing footage of leporid acrobatics in an archival film from the days of the British Raj. An Indian  hare (Lepus nigricollis) dodged and turned, and leapt gamely over a slobbering and snapping German shepherd.

There was no contest. The hare's locomotory skills so excelled those of that particular dog that it would surely have escaped if it hadn't been penned.

If you view running rabbits in slow motion you gain a heightened appreciation of things you just don't see in real time -- namely, the pounding interaction of gravity and acceleration on flesh and joints.

Functional morphologist Dennis Bramble analyzed film of running black-tailed jackrabbits and found that the G-loads or decelerating forces acting on the forelegs of a 5-pound Jack averaged 3.5 G during a fast gallop.

The loads were as great as 12 G when they touched down after high observational leaps.

The jackrabbit's jarring run led Bramble to examine the structural adaptations for dealing with the head-rattling effects of high speed locomotion.

To that end he examined jackrabbit skulls and cadavers and concluded that the curious areas of latticed skull bone (fenestra) are more than a diagnostic curiosity of leporids.

Fenestra confer strength without the weight of solid bone, and a light weight head is more easily stabilized when the body is moving at high speed.

High speed film of running Jacks shows that the head floats quite steadily ("undergoes minimal angular exursion") in relation to the bounding motion of the body.

In fact, the swift jackrabbit's head weighs about 55% of the slower European rabbit's head of the same size. (And by the way, the European rabbit, Oryctolagus cuniculus,  runs only 56 km/hr.)

The jackrabbit's skull has an even stranger feature. The braincase is hinged near the base of the skull with something that approximates a woodworker's box-joint. This is the intracranial joint  or ICJ.

Bramble manipulated the heads of fresh cadavers and found that the ICJ is moveable over a small range not exceeding 1 mm.

A galloping jackrabbit subjects the ICJ to an alternating rhythm of impact loading, and the jointed skull seems to serve as a shock absorber.

It works like this.

When the jackrabbit lands on its forelegs a decelerating force opens the hinge and the anterior part of the skull moves forward. The ears swing slightly forward too.

When the jackrabbit pushes off with its hind legs the accelerating thrust closes the hinge and the ears swing backward a bit.

A few words on Jack's ears: their mass is almost one third that of the head, and they bridge the ICJ via large frontalis muscles -- the only muscles to span the skull hinge directly.

If you are wondering why a galloping jackrabbit would increase aerodynamic drag by holding those big ears erect, Bramble hypothesized that they play a role in restoring the cranium to its normal preloaded condition when the cranial hinge is closed.

If you are still doubtful you are probably wondering if the cooling function of the ears explains their upright position while running.

Well it doesn't, because the ears' radiator function normally kicks in when the rabbit stops running.

So the question remains: is the ICJ and cranial kinesis a biproduct of having a light head?  Or is something else going on?

Bramble believes the most likely target of shock absorption is the jackrabbit's large eyes.

With a visual field of +360 degrees, stereoscopic vision in front of and behind the head, and extraordinary movement detection, rabbits are supremely sighted, and not just to detect danger.

While pursued by predators they are able to navigate the rapidly changing obstacle course ahead while visually tracking their pursuers behind -- and they do this usually at night.

The venous sinuses that surround the eyes lend support to this idea. The sinus vessels lack valves and respond to pressure changes due to movement of the ICJ.

One possibility is that the sinuses maintain constant pressure on the eyes because blood shunts back and forth between them when the intracranial joint expands and contracts.

There's more to the hypothesized mechanism than that.

The ICJ may clamp off the temporal vein and divert blood to sinus hydraulics that assist shock absorption -- all of which has implications  for the evolution of leporids, skull fenestration, and high speed chases.

I believe Professor Bramble has made it quite clear that Jack has a lot going for himself.

Admire him not only for having the fastest feet in the West (at least for his size), but also for his lightweight and hinged head. 


Bramble, D.M. 1989. Cranial specialization and locomotor habit in the Lagomorpha. American Zoologist, 29:303-317.

Best, T.L. 1996. Lepus californicus. Mammalian Species, No. 530:1-10.

Garland, Jr., T. 1983. The relation between maximal running speed and body mass in terrestrial mammals. Journal of Zoology, 199:157-170.


Wood, A.E.. 1957. What, if anything, is a rabbit?  Evolution 11:417-425,

Wednesday, May 5, 2010

Richard's bird box monitor

It's one thing to have a pair of oak titmice move into your bird box.

It's another thing to sit in your TV room and witness the events going on inside the box.

A couple years ago I gave neighbor Richard a bird box, and this spring he equipped it with a cheap security cam wired it to an old black and white TV monitor.

He's been bearing witness to the timeless but fleeting drama of avian growth and development.

Today I stopped by to see for myself.

One of the chicks was flapping and climbing over its siblings, and I observed that "fledging is just around the corner".

"Then I've got to catch that stray cat soon."

"You betcha". Fledglings are delectable morsels to cats, but one hardly makes a meal.

Richard says that there's a frenzy of feeding just before sundown.

Mom and dad come and go, and the chicks gobble moths, poop and grow.

As a distraction to the boob tube, my neighbor prefers the bird box to commercials.

Monday, May 3, 2010

Lonesome otter

Ever since PG&E drained the flume a couple weeks ago -- mainly to remove dead trees on the banks -- I've had an eye open for bank burrows.

Last year I saw otters dive and disappear into the banks in several places, and now I've had a chance to confirm the presence of burrows.

The burrow left of center for example is normally underwater, and in the summer it's completely hidden by Indian rhubarb.

Today we stumbled on a lone otter and I found another burrow.

The muddy water caught my eye, but I assumed it was due to someone's dog.

The next thing I knew Fred was in the water, and I saw a flash of movement under the surface -- the otter.

Otters can tooth-slash a dog as easily as a person, and it took only a few excited curses to get Fred out of the water.

But this otter behaved oddly -- it refused to leave the area, and it didn't retreat into the nearby burrow.

So while Fred fidgeted on the berm I took pictures as the animal rested on the gunnite bank.

Its small size told me it was a female.

Possibly there's a litter in that burrow, but if so I'd expect an aggressive male to be present.

I got the feeling she is an outcast.

Who knows? . . . Maybe the scars on her shoulder and flank were from a fight.

Signs of old age were there too. Her lower canines were broken off at the gumline.