Category Archives: upper las virgenes canyon open space preserve

Guardian Oaks

Young valley oaks and coast live oaks at the edge of the canopy of large valley oak in Upper Las Virgenes Canyon Open Space Preserve.

One day while running at Ahmanson Ranch, I was admiring the stately limbs of a large valley oak, and noticed that along the margin of the canopy were several sapling oaks. As I continued my run, I found that only a few other valley oaks hosted a brood of young trees.

That oaks would sprout on the margin of the canopy made sense. There is an abundance of acorns at the ends of the limbs. It is also where water drips from the oak’s leaves on foggy days or when there is light rain or drizzle. The mix of sun and shade on the edge of the canopy is the perfect place for a young oak to thrive.

The surprise came when I took a closer look at the young trees. Most were valley oaks — the same as the shepherding tree — but in some cases the young trees were coast live oaks! And sometimes there was no obvious parent coast live oak nearby.

Of course, there are plenty of coast live oaks at Ahmanson and several ways for their acorns to find their way under a valley oak. Birds and squirrels love to stash acorns, and gravity is good at moving round things downhill.

Time is at a different scale for a tree. In my mind’s eye I accelerated time and watched as the young oaks surrounding a guardian oak grew in stature. Fire sweeps through the frame on several occasions. During one fire the old brood tree collapses and in another fire, the collapsed tree disappears from the frame. Of the young oaks that have survived, one dominates, spreading its limbs and growing large and robust. Along the margins of its canopy, I can see several sapling oaks…

Note: The young oaks in the title photo are an older brood that survived the Woolsey Fire, but many younger sapling oaks were killed. Introduced grasses, black mustard, and other introduced plants produce higher fuel loads than native equivalents and increase fire mortality.

Chinese Houses Along the Sheep Corral Trail

Chinese Houses (Collinsia heterophylla) along the Sheep Corral Trail

Wildflowers continue to flourish following our wet rain season. Above average precipitation tends to produce more wildflowers, a wider variety of wildflowers, larger patches of a wildflower species, larger plants, and in some cases larger blossoms.

During the week I photographed several new “Weekday Wildflowers” on runs from the Victory Trailhead of Upper Las Virgenes Canyon Open Space Preserve. This week’s runs included Lasky Mesa, Upper Las Virgenes Canyon, and the Sheep Corral Trail.

Chinese houses, white snapdragon, yellow monkey flower, stinging lupine, and a few other species were added to the Weekday Wildflowers slideshow.

Related post: Weekday Wildflowers

Northern Harrier Turning to Strike

Northern harrier turning to strike prey

Dusk is a dangerous time. Death glides through the shadows, stealthy and quiet. Retreat to your burrow, stop munching those sprouts, silent wings and sharp talons are out and about.

It was after sunset and I was in the last miles of a run at Ahmanson Ranch. A few minutes earlier I’d noticed a pair of northern harriers crisscrossing the grasslands of Lasky Mesa. Now on the east side of the mesa, with the light fading, I saw them again. This time they were flying together — one in lead and one in trail — and making a low, sweeping pass, just a few feet off the ground.

Pair of northern harriers, hunting at dusk, on Lasky Mesa
Pair of northern harriers, hunting at dusk

Northern harriers have an owl-like facial ruff, and can hunt using sound, as well as vision. Obviously hunting for prey, they continuously made small adjustments to their flight paths, overflying one interesting spot and then another. There were calls between the birds — a dialog seemingly related to the hunt.

Was that movement? I’ll check. No. Did you check there? Yes.

Their behavior had been intriguing enough that I had stopped to watch. The harriers were backlit by the western sky and I snapped a photo of them flying in a leading/trailing formation. I had taken a photo of the lead bird and had just switched to the trailing bird when it suddenly spread its sleek wings and tail, pivoted into an impossible turn, briefly hovered, and then pounced on its prey.

The time from the first photo of the pair to the turn and strike was 18 seconds. It was remarkable to see!

Related post: Northern Harrier on Lasky Mesa