Tuesday, April 27, 2010
You might recognize the location from the previous post.
For reasons known only to it, the Peromyscus or white-footed mouse shimmied up the re-bar and returned to ground zero.
Cute, but the curious thing is the use of the tail.
It is semi-prehensile.
It can't seize and grip like a true grasping organ, but it can wrap around a twig, stem, or a piece of re-bar to give the body a small added measure of support.
Some climbing rodents, like most species of prehensile-tailed porcupines, Coendou have true grasping tails.
But most arboreal rodents have tails that are balancing organs.
In general, the more arboreal the rat or mouse the longer the tail, but only up to a point of course.
They also have the ability to wrap the tail around a twig in an incomplete spiraling coil.
Thus the semi-prehensile tail that comes into play as the mouse inch-worms down the rod.
When it relinquishes the grip of the hind legs to move forward, there's a danger of the mouse's big butt swinging out and away from the perch.
The semi-prehensile tail keeps the mouse's center of gravity close to the perch.
You have to admire their versatility.
Sunday, April 18, 2010
Can you see it? It's a crappy image, but it's good enough . . .
When you're squinting at your camera trap images on the LCD in the glaring sun it's easy to miss the little guys, even if they're giants among their kind.
So the thrill of seeing a new species in the latest Chimineas survey was delayed until the jpegs were uploaded to computer.
Mind you, I can't swear that the small blobular creature on the right is Dipodomys ingens, but compared with other photos I have a strong hunch it's the real thing.
Among kangaroo rats, Dipodomys ingens is a giant, with larger males weighing in at as much as 140 g (= 0.3 lb) when they are bulked out in the month of August.
Equally appropriate names would be the big-footed or big-headed kangaroo rat because the head and hindfeet are oversized compared to most other kangaroo rats.
We knew ingens was on the ranch because their skulls litter the ground beneath the winter roosts of the long-eared owls.
It was a welcome addition to our mammalian species list.
Craig photographed it in annual grassland.
The lovely big-eyed rat probably had a patchy distribution even before Father Junipero Serra and his followers drove cattle up el Camino Real and scattered Mediterranean weeds across the western plains of the San Joaquin valley.
When Joseph Grinnell was digging up k-rat burrows in the early '30s ingens colonies were spread across thousands of acres of rangeland.
Wherever Grinnell and his contemporaries found ingens, it reigned supreme over other rodents, "--it 'owns' whole square miles to the practical exclusion of other seed-eating rodents."
Even California ground squirrels were largely absent in giant kangaroo rat country.
This is puzzling because kangaroo rats and ground squirrels work different time shifts, and ecological theory predicts this difference should at least reduce competition when resources aren't severely limited.
The State Water Project of the '60s and '70s changed the situation by irrigating the western part of the Tulare Basin, which fragmented the saltbush community and converted most of it agroscape.
The k-rat disappeared over a large segment of its former range, and in the 1980s the State of California and US Fish and Wildlife Service listed the giant kangaroo rat as endangered.
The Carrizo Plain remains a giant kangaroo rat stronghold, but a strange thing has happened there: the rat has formed an unsavory alliance with alien weeds from the Mediterranean.
The k-rat likes the big seeds of five annual weeds, and two of them, redsteam filaree (Erodium cicutarium) and foxtail brome (Bromus madritensis) thrive and dominate the flora in the rats' precincts, the most active parts of their home ranges.
The k-rats gather and cache the seeds in granaries, and when it rains some of them sprout in the disturbed soil, which the k-rats prepare and till by nightly digging, burrowing, dust-bathing, and plant clipping activities.
An endangered kangaroo rat that cultivates undesirable exotic weeds is a Catch-22 for conservation biologists.
You may not be able to eradicate the weeds and restore the grassland without threatening the k-rat -- and if you hasten the k-rat's recovery you'll spread the exotic weeds.
This may be a case where you can't have it both ways.
Save the giant k-rat and the weeds are here to stay.
Grinnell, J. 1932. Habitat relations of the giant kangaroo rat. Journal of Mammalogy 13:305-20.
Schiffman, P. 1994. Promotion of exotic weed establishment by endangered giant kangaroo rats (Dipodomys ingens) in a California grassland. Journal Biodiversity and Conservation. 3(6):1572-9710.
Williams, D.F. and K.S. Kilburn. 1991. Dipodomys ingens. Mammalian Species No 377:1-7.
Williams, D.F., M.K. Davis and L. P. Hamilton. 19 95. Distribution, population size, and habitat features of giant kangaroo rats in the northern segment of their geographic range. Bird and Mammal Conservation Program Report 95-01, State of California Department of Fish and Game, 44 pp.
Saturday, April 17, 2010
We were working in the garden yesterday when Fred found a large gopher hole and went terrier.
The dirt was flying.
The redhead advised me to curb his activity -- "He'll undermine the walkway".
"He's burning action specific energy," I replied, "and look at him . . . the little guy's helping us in the garden. It's kinda sweet."
When we had finished the raised beds, I set a gopher trap to validate Fred's helpfulness.
This morning I checked the trap, and the gopher got away.
And Fred had indeed undermined the walkway; so that has to be filled and packed, hopefully after I catch the gopher.
Once again the redhead was right.
Wednesday, April 14, 2010
When I let Fred out for his morning constitutional about a month ago he bee-lined to something near the driveway.
It was a fresh jackrabbit carcass.
There was hair all over the place -- something had plucked it, and chewed at it with small jaws.
Maybe a domestic cat, I thought.
When I went to set a camera trap later in the day I found that it had been dragged down the hill.
Ravens and vultures had pretty much finished it off.
The carcass was gone the next day and there were no pictures on the camera, but I left the camera there and forgot about it.
Yesterday I remembered the cam and pulled it.
There was still some hair on the ground a couple weeks later when a gray fox and a striped skunk visited and sniffed the area.
It's not a surprise.
When a mountain lion peed on a mossy rock a few years ago, it killed the moss.
It also continued to attract passersby for several weeks.
Monday, April 12, 2010
California poppies with the Sierra Madre in the background.
The South end of the ranch.
The Redhead and I met Randomtruth and Craig at Chimineas last week.
The wildflowers were out of control and the urge to muse and write poetry kept interfering with camera trapping duties.
Randomtruth got rather carried away with taking photos, and I am not going to even try to compete with him.
He is way too good.
Check out his Nature of a Man Blog for scenery, flowers, and adorable creepy crawlies -- he'll be posting on Chimineas soon.
Meanwhile, here's one more photo to whet your appetite for spring on the Carrizo Plain.
(Sigh) In a couple weeks it will look like it does most of the year -- the gritty backdrop to a black and white western.
Thursday, April 1, 2010
Kit fox positions itself for measurement.
I have to hand it to Craig for coming up with the measuring stick idea.
What better way to distinguish three canids like kit fox, gray fox and coyote when they are standing there in the distance?
Sometimes pictures just aren't good enough.
Just measure the shoulder height of your subjects.
It's a legitimate morphometric for separating these three species.
It's hard to judge body size without a reference, but it's not a problem when the animals stand next to the measuring stick to sniff their favorite brand of stinkum.
Okay, you do have to take camera angle into account, but a little trigonometry never hurts.
The bigger problem is maintaining maximum visibility of the measuring stick.
That grass grows like crazy at this time of year, and Craig is spending a lot more time riding the mower these days.