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Once abundant throughout the Mojave Desert, the population of the desert tortoise, Gopherus agassizii, or Agassiz’s desert tortoise, continues on a steep decline despite the efforts of many environmental groups, biologists and volunteers. A recent article in the Los Angeles Times - “California’s Mojave Desert Tortoise Moves Toward Extinction” Nov. 17, 2022 by Louis Sahagun - details this decline and explains why reversing it - while not impossible - is very challenging.   According to this source “eight decades ago, the vast Mojave Desert was home to hundreds of tortoises per square mile… Today, most tortoise populations in California and outside designated recovery areas have fallen to 2 to 3 adults per square mile…” Threats to the desert tortoise come from many sources including habitat destruction due to housing development, industrial solar installations, military maneuvers and desert recreation; decrease in food and water sources due to climate change; and increase in predator populations of feral dogs, coyotes and ravens. 

Ravens, once rarely seen in the Mojave, are now common, particularly near human housing and recreation areas.  Fearless, aggressive and very intelligent, ravens have learned to raid trash cans and other sources of  food inadvertently provided by people. Ravens are particularly deadly to newly hatched tortoises whose soft shells provide little protection. Like ravens, coyotes have adapted well to living with people and have a taste for tortoise hatchlings. Coyotes also have been known to prey on adult tortoises by digging them from their burrows during times when other food sources are scarce. 

The desert tortoise is very long-lived but also takes several decades to reach sexual maturity. Females lay 1– to 14 eggs between April through June; number of eggs seems to be dependent on the size and age of the female. Females dig nests with their hind legs and then carefully cover the nest. When the eggs hatch, generally from 70 to 120 days, the young are on their own. Wildflowers are a favorite food for all tortoises. Desert grasses and cactus buds are also eaten. Tortoises must drink water. They become noticeably more active after rainstorms in the spring, summer and early fall. They hibernate generally from October to March. 

What can individuals do to help the Mojave desert tortoise? Here are a few suggestions:

Secure your trash.  Close lids and do not let trash overflow. When recreating, pick up your own trash and while you are at it, look for other trash that you can take with you as well. If a campground or city park picnic area does not provide secure trash receptacles “pack it in and pack it out.” Slow down. Tortoises are attracted to roadsides when water accumulates alongside pavement. This is a particular problem after desert monsoon rains. PRMDIA helps with the effort to slow traffic on desert roads by financing the printing of postcards provided free to the public at Mitchell Caverns (inside the Providence Mountains State Recreation Area).  Suggested and designed by State Park Interpreter Andrew Fitzpatrick, these postcards urge the public to slow down when driving in the desert and never touch a tortoise unless it is in danger of being hit. (Learn more about how to safely move a tortoise by reading this information provided by Joshua Tree National Park: www.nps.gov/jotr/learn/nature/tortoise.htm)Learn more.  Providing protection for desert tortoises, important research and many sources of education for the public, the Desert Tortoise Research Natural Area lies on the western edge of the Rand Mountains, northeast of California City. This protected area provides 39.5 square miles of prime tortoise habitat. It is open every day. Visit in person and/or read through the extensive information on their website:
 tortoise-tracks.org.

For more information:
View a video based on the LA Times article mentioned above.

Mojave Desert Tortoise  Postcard - Mitchell Caverns, Providence Mountains S.R.A.Provided by PRMDIA at no charge to the public

Painted Ladies of the Desert
President's Message March 2022
by Margaret Rhyne - president@prmdia.org 

A trip to the Poppy Reserve in early February resulted in a nice surprise. As newsletter editor Marsha Neill and I scanned the field in front of the Jane Pinheiro Interpretive Center for some telltale hints of orange, we spotted something unexpected, a few out of season rabbitbrush blooms and fluttering over them, a painted lady butterfly making an appearance at the Reserve a month ahead schedule. Unfortunately, this orange and black monarch butterfly look-alike provided the only flash of color at the Reserve that day, but it was a welcome sight nevertheless. 

Painted ladies (Vanessa cardui) are the most widespread butterfly throughout the world. They are found on all continents except Antarctica and South America. Beginning in March, painted ladies fly from northern Mexico north over most of California with offspring reaching as far north as the Pacific Northwest and Canada.  This is not a roundtrip migration because they rarely migrate south and return to northern Mexico. Instead each individual butterfly only makes it a few 100 miles north before stopping to lay their eggs and die. Their offspring will continue the journey north a few 100 miles farther before reproducing, driven by genes that tell them to “move away from the sun and fly toward darker skies,” according to desert researcher Jim Cornett. It takes about 6 generations to reach their final northern destinations. The last painted ladies of the season will then die out. 

Fortunately, every year some painted ladies resist the urge to fly north and instead stay in northern Mexico, keeping the population intact. In addition, a few offspring from the northern migrations may head south at the end of summer and return to Mexico, also helping to preserve the species through the winter. Unlike the monarch butterflies that they resemble, they do not overwinter in California. On their journey north, painted ladies can fly up to 25 to 30 miles per hour and continue for days without stopping. Along the way, as they lay eggs and harvest nectar, they play an important role in the pollination of native wildflowers. 

In wet years, the northern journey of painted ladies can be quite spectacular, with millions of butterflies filling the skies. In 2019 my husband and I were amazed by the early morning view of a sky filled with their fluttering orange wings while on a March visit to Borrego Springs. Later that day, we found the same masses enjoying the wildflower fields at the entrance to Coyote Canyon in Anza Borrego State Park. In 2019, the Poppy Reserve also was visited by large numbers of painted ladies. 

Host plants include Mojave thistle, sagebrush, desert globe mallow, and most native lupines. Nectar is provided by the flowers of thistles, blazing stars, asters, and many other plants. At the Poppy Reserve, look for painted ladies on the grape soda lupine and fiddleneck. When looking for the proper host plant for its eggs, female painted ladies, like most butterflies, uses taste receptors on the bottom of its feet. The mint green eggs are barrel-shaped. The eggs hatch in 3 to 5 days. It takes about 4 weeks for the entire metamorphosis from egg, to larva (caterpillar), to pupa (chrysalis) to produce an adult butterfly. 

If you return from a wildflower watching trip to the desert with a yellow smear on your windshield, you probably have had an unfortunate encounter with a painted lady. When the painted ladies smash into a windshield, the result is a glob of yellow, butter-like ooze caused by the butterfly’s stored fat, used to make the long journey north. Their large numbers and low flying habits make this a common occurrence in wet years. 
Links:
Calscape: Painted Ladies
10 Fascinating Facts About Painted Lady Butterflies
University of Colorado

Links for Photos below left to right:
Painted Lady Butterfly 
Comparison, Painted Lady and Monarch

Bird or Insect?

The “hummingbird moth” often seen throughout the Mojave Desert is a startling surprise to visitors at our desert state parks. Known commonly as the white-lined sphinx moth (Hyles lineata) its behavior and large size cause it to be often mistaken for a hummingbird. It is a chunky moth with six white strips across its brown body and a wingspan of 2 ½ to 3 ½ inches. The hindwings have pink streaks. The caterpillar of the white-lined sphinx moth is usually dull yellow in the west but color varies and can be off white and sometimes nearly black. Because of its large size, the white-lined sphinx moth must beat its wings very fast, enabling it to hover like a hummingbird as it sips nectar. At the poppy reserve look for them on Kitanemuk Point hovering over the lacy phacelia. Other desert plants that attract this striking moth include California buckwheat and California four o’clock. In California, there are 21 different species of sphinx moths. 

White-Lined Sphinx Moth
Photo courtesy of Bruce Blackadar