Are these fall colors – hues of orange amidst the green of trees? No, they are not leaves at all. On closer inspection, these are clusters of orange and black colored Monarch Butterflies. Tens of thousands make the annual trip down from Canada to escape the brutal winters. And they rest in a handful of Eucalyptus trees in Monarch Grove, Pismo Beach in California, USA. The butterflies form dense clusters with each one hanging with its wing down over the one below it to form a bunch. Such formations help keep them warm. These clusters look like yellowed leaves up in the trees, until the sun hits them. And then…..they take flight…..
The journey of Monarch Butterflies
Weighing less than a gram, monarch butterflies travel thousands of miles starting fall from colder climes to warmer places. They are in search of places that provide the right microclimate to enable them to survive for months with little food or water. Scientists have been studying their migration patterns for decades now. As of today, we know that monarchs migration path depends on their origins in the northern Canada. Those on the east side of the Rockies start the journey to the upper Midwest during fall. They reach Texas or even further to Mexico by the next spring before dying. The successive generations then make their return journey as summer temperatures rise reaching Canada at the advent of fall. Monarchs that begin their journey west of the Rockies do something similar: after wintering on the coast of California, shielded by stands of eucalyptus or Monterey pine, they move inland to the Central Valley, but also north to Washington State and southern British Columbia, and to Nevada, Arizona, Idaho, and possibly Montana.
Monarchs are large, beautifully colored butterflies that are easy to recognize by their striking orange, black, and white markings. They live in North, Central, and South America as well as Australia, some Pacific Islands, India, and Western Europe. The wingspan of a full-grown monarch can reach nearly five inches (13 centimeters), although the average is closer to four inches (10 centimeters).
Their markings include bright orange wings covered with black veins and rimmed with a black border and white dots. Females have thicker veins in their wings. A monarch’s brilliant coloring tells predators: “Don’t eat me. I’m poisonous.” The butterflies get their toxins from a plant called milkweed, which is their only food source in the caterpillar stage. An animal that eats a monarch butterfly usually doesn’t die, but it feels sick enough to avoid monarchs in the future.
These international travelers return to the same forests each year, and some even find the same tree that their ancestors landed on. Some estimates say up to a billion butterflies arrive in the mountains of Mexico each year. Scientists aren’t sure how migrating monarchs know which way to go, since they only live a few months and none makes the journey more than once. Toward the end of winter, the monarchs in Mexico and California mate. The males then die, while the females head north, depositing eggs on milkweed plants along the way and eventually dying themselves. From these tiny, round eggs come small green-and-white-striped caterpillars, which feed on the milkweed leaves. For about two weeks, they eat constantly and grow by shedding their skin. They are then ready to transform into pupae. To become a pupa, also called a chrysalis, a monarch larva attaches itself with silk to a leaf or branch, sheds its skin, and forms a hard shell. This vase-shaped case starts out green with shiny golden dots and slowly becomes white, then see-through. After 9 to 15 days, a fully formed butterfly emerges. The entire egg-to-butterfly process, called metamorphosis, takes about a month.
Scientists think North American monarchs have been making their amazing annual journey for thousands of years. But logging in Mexico has greatly reduced forests where these butterflies roost. Efforts to protect these lands are helping, but illegal logging still takes a toll.
During 1990s, it was reported that while the monarch butterfly was not an endangered species, ts North American migration patterns were at grave risk of disappearing. Less than two decades later, in 2013, that danger appeared to have come to fruition, when that winter’s monarch population covered less than three acres of the Mexican forest, down from around twenty acres ten years earlier.