Butterflies and the Superbloom

The dwarf purple carpets of California filaree (a geranium) on the Anza-Borrego SP heights were a favorite of migrating Painted Ladies borne aloft by desert thermals; the butterflies often dropped out of flight as the temperatures plummeted at higher altitudes. [2019 March 4, photo by REB]

Seems like butterflies are everywhere in the news these past few weeks, driven in large part by the stunningly massive migration of Painted Ladies (and a few other vanessids) in southern California.  By sheer luck I had planned to be out there for the superbloom already the first week of March, so I got to check off a terrific botantical bucket list *and* see the butterfly hordes.

Parts of the desert superbloom were mostly yellow; in this case, desert sunflower [2019 March 3, photo by REB]

Elsewhere, the flower carpet was mostly purple from sand verbena [2019 March 3, photo by REB]

And superbloom is really was/is; given the weather conditions this desert bloom may actually have several peaks depending on when and where the rain falls.  When I was there, parts of the east end of Anza-Borrego Desert SP were plains of purple and pink with sand verbena and dune primrose; on the west side, the desert floor was golden with desert sunflower.  Brown-eyed Evening Primrose was blooming everywhere (and beginning to host good numbers of White-lined Sphinx caterpillars, which will in turn become the feast that draws in migrating Swainson’s Hawks about now).

White-lined Sphinx caterpillar on brown-eyed evening primrose in Anza-Borrego Desert State Park [2019 March 3, photo by REB]

It’s been interesting to see the coverage of the Painted Lady movement; many of the news accounts seemed to attribute the migration to butterflies being “attracted to” the superbloom.  While the two phenomena are related, it’s more likely that the same conditions that spawned the superbloom also spawned a superabundance of larval food for the butterflies.

At one point on an early March morning, at about 8 am with an ambient temperature of around 42F., I stood on a high ridge on the Montezuma Grade looking down about 2000 feet onto the desert floor around Borrego Springs in the middle of the park.  The sun was bright after a couple of days of drizzle and clouds; thermals were already lifting birds of prey up out of the valley onto the heights.  They were also lifting clouds of Painted Ladies; for one 20 minute period I could count on seeing several thousand butterflies *at one time* come up from the valley floor through a ravine and up over the road.  Once they hit the cool air on the ridge; many of them dropped onto the vegetation and surrounding rocks to wait for warmer temperatures.

It was a good trip; in addition to the ladies I also saw Funereal Duskywing, both Sara and Desert Orangetips, and my first Mourning Cloak of the year.  And scored a number of life birds, including California Gnatcatcher.

Basking Funeral Duskywing in Palo Verde Wash. [2019 March 3, photo by REB]

Orangetips were also on the wing, this one in Plum Canyon [2019 March 4, Anza-Borrego Desert SP, photo by REB]

On the California coast in Solana Beach, this Silvery Blue was visiting cresses in San Elijo Lagoon [2019 March 7, photo by REB]