Friday, March 11, 2011

Plum Canyon

We're in Anza Borrego State Park, which showcases the Colorado Desert of southern California. Colorado Desert is basically Sonoran Desert, minus the Saguaro, and with other differences in plant and animal species. It is the Californian expression of Sonoran Desert.

Not far to the north, the habitat grades into Mojave Desert, well-expressed at Joshua Tree National Park. The two deserts, although close to each other, have different rainfall regimes. Mojave Desert is a land primarily of winter rains, while Sonoran Desert receives both winter and summer rains more frequently, and is the lushest of the four North American deserts.

Here at Anza Borrego, Plum Canyon is accessible via a mile-long, primitive road, and a plum of a canyon it is! We've come in search of Sonoran Blues, a very local California butterfly, and one that I've not seen before. Noel is most interested in obtaining photos of the spectacular female, while I just want to see the beast!

Hillside at Plum Canyon (Photos by Narca)

Desert Lavender (Hyptis emoryi) is in the mint family.

We car-camp in Plum Canyon, which is out of the way enough that there is rarely another camper, although it is often visited during the day. The dawn light reveals masses of flowering Chuparosa and Desert Lavender, with California Barrel Cactus and Teddy Bear Cholla cloaking the slopes of the canyon. A short hike upstream brings us to the first Desert Dudleya, the host plant for Sonoran Blue caterpillars.

Desert Dudleya (Dudleya saxosa) adorns the walls of Plum Canyon. 

California Barrel Cactus (Ferrocactus cylindraceous)

Chuperosa or Beloperone (Justicia californica)

We split up in order to cover more ground, a strategy that pretty much guarantees frustration for everyone, as special critters may be seen by one party but missed by the other! And indeed, Noel spots a Western Tailed Blue, which I've never seen, and I find three Bramble Hairstreaks, which he has never seen. But we are both lucky with the grail species, for the Sonoran Blues are flying!

Bramble Hairstreak

Next challenge: yes, they are flying, but are any sitting?

Butterflying requires different strategies and a different nuance of patience from birding. We tramp the canyon for hours and catch numerous glimpses of our quarry. Finally we return to the cars, and just at the trailhead, a male and a female Sonoran Blue discover each other, and with no preliminaries at all, settle down to the serious business of making the next generation of Sonoran Blues.

Amorous Sonoran Blue butterflies

A male Sonoran Blue pauses briefly in his patrol of Plum Canyon.

Forty minutes later, the task has been accomplished, and the male quickly flits away, while the female lingers briefly, working her hind wings vigorously, after the manner of a hairstreak.

A female Sonoran Blue, ready to search out Dudleya to lay her eggs.

Au revoir, little friend!

Our butterflies live in a precarious world, where human activities and changing climate impact their seasonal cycles and their food plants. Even here at Plum Canyon, the last time that Alan, Noel, Jim and I visited, we found that a plant collector had been illegally digging up the Dudleya, the Sonoran Blue's host plant, no doubt for sale to rock gardeners. Noel's favorite side canyon had been ravished by the plant collector––and very recently, for the little holes still remained where the plants had been rooted. This trip, thankfully, we saw no evidence of illegal collecting.

For an outstanding article on the work which Art Shapiro at University of California, Davis, has been doing to correlate climate change with loss of butterfly species, go to this link:

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