Monarch butterflies have fascinated humans with their vivid black and orange colors. What's more fascinating is their ability to journey for up to 3ooo miles or 4800 kilometers. Sadly, the population of these remarkable insects is relatively declining.

Based on the Biological Conservation journal's study, the population of the monarch butterflies from western North America has radically shrunk than previously thought. This species is more prone to be wiped out compared to the eastern monarch butterflies.

According to the associate professor at Washington State University Vancouver and lead author of the study, Cheryl Schultz "Western monarchs are faring worse than their eastern counterparts. In the 1980s, 10 million monarchs spent the winter in coastal California. Today there are barely 300,000."

She added that the western monarch butterflies might vanish in the coming eras if measures will not be taken to replenish its population.

Eastern monarch butterflies spend winter in Mexico while western monarch butterflies vegetate near the coast of California's forests. It lays its eggs on milkweed in spring and feasts on the nectar of the flowers that flourish in Arizona, California, Nevada, Oregon, Washington, Idaho, and Utah. During fall, these beautiful insects revisit their overwintering ground, the Washington State University points out.

It was in 1990 that Californian residents who live near the coasts noticed that the western monarchs seems to be vanishing and was confirmed by the Biological Conservation study. The data was acquired from the counts done by both amateur and professional butterfly participants during the 1980's and early 1990's. The information was integrated with the data gathered from counts conducted by the Xerces Society's Western Monarch Thanksgiving Count since 1997.

According to a National Geographic report, only monarch butterflies that were born in late summer or in early fall can survive the migration with just one round trip. When the next year's winter migration starts, more generations that hatched during the summer would have survived and died and is going to be the last trip for the great grandchildren of the last year's migrators.