The coastal sites, stretching in a narrow band from San Diego to Mendocino County, provide the ideal climate for monarch’s winter diapause, a period of decreased resource consumption and suspended biological development similar to hibernation. Trees (including eucalyptus, Monterey pines, sycamores, coast live oaks and willows in Southern California), shelter groups of monarchs in camouflaged clusters, with wings closed showing only the tan underside in overlapping layers, resembling dead leaves. Monarchs begin arriving on the California coast in October and leave around February to begin looking for suitable sites for reproduction in California and other western states, west of the Rocky Mountains. Eastern monarchs overwinter mainly in Mexico and migrate to areas of the U.S. and Canada east of the Rocky Mountains to reproduce.
Current monarch populations remain seriously threatened. 2018 through 2020 were disastrous years for western monarchs. At the Pismo grove, just 122 butterflies were counted during the winter of 2020. Although the 2022 count showed a promising rebound of 24,128, western monarchs have decreased 90% since the early 1990s. (Source: Xerces Society)
Are there monarchs overwintering in the desert? Yes! In 1976, monarchs were observed spending the winter in canyons of the Inyo Mountains adjacent to the Saline Valley. In 2016 formal winter counts began in these canyons and are continuing this year. (See Saline Monarch Count for more information.) A few areas in the Sonoran Desert in Arizona are also known overwintering sites.
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: About the Desert Tortoise.
For more information:View a video based on the LA Times Article mentioned above . Also: Wild Kingdom Protecting the Wild