Sunday, August 26, 2012

Amazing Migrating Monarch Butterfly

Mereka tampak seperti daun atau kelopak bunga, dekorasi pohon dalam nuansa dramatis oranye dan hitam. Namun pada kenyataannya ini adalah kupu-kupu Monarch, salah satu yang paling dikenal dan paling menarik dari spesies kupu-kupu di Amerika Utara. AMJG pernah menampilkan foto-foto indah dari kupu-kupu dan moth sebelum postingan ini. Sekarang saatnya untuk berbagi foto-foto kupu-kupu monarch yang sedang berjamaah yang tak kalah menakjubkannya.

When we think of animal migrations, we normally think of birds, or perhaps a few herd animals such as wildebeest. One creature that doesn’t instantly come to mind is the butterfly; yet migrating is exactly what these pretty insects do, en masse, once a year. And if you’re lucky enough to be in the path of their annual passage, you’re likely to see big groups of these beautiful creatures gathered together, as we’ll see in these photographs.

Like the wildebeest mentioned earlier, these butterflies have ‘gathered at the watering hole' (so to speak) for a bit of a drink. They do this by sucking up the water through their straw-like proboscises – the butterflies’ equivalent of mouths for their liquid diet.

Two clusters of butterflies fill twin branches, seen here against a lovely blue sky. Apart from water and nectar, the monarchs also like to suck up a bit of mushy fruit when they can – as long as they don’t get any lumps stuck in their proboscises!

In this huge swarm, it’s hard to see the butterflies for the… well, butterflies. This particular crowd is gathered at the El Rosario Butterfly Sanctuary in Michoacán. Each year, some of the winged insects travel roughly 1,250 miles from the Rocky Mountains to winter in this part of Mexico.

In recent years, the number of butterflies wintering in Mexico has fluctuated wildly, dropping by as much as 75% a couple of years ago. Fortunately, this may not be as worrying as it seems, as that number doubled this year. Monarch butterflies in other countries also migrate with the season, but it's those in North America that travel the greatest distance.

There are two migrating populations in North America. Those monarchs that live east of the Rocky Mountains fly down to Mexico, while the more western population stops in California. Monarchs do not like the cold, and as soon as things start to get a little chilly up north, they take off south (and west) for warmer climates.

Even with their striking color combination, these butterflies blend in with the leaves so perfectly that they’re a little hard to see. This particular crowd is enjoying its winter vacation in Santa Cruz, California. You may wonder why the monarchs don’t simply stay and enjoy the warmer weather here year round. That’s because they need the milkweed plants on which their larvae feed, and those are more plentiful up north. So as soon as the weather starts to warm up, that’s where they return.

Looking like a cluster of strange fungi, these butterflies are gathered on the bank of a stream in Michoacán. The government of Mexico has managed to almost stamp out logging in the monarch’s wintering areas, a practice which once threatened the migrating insects. Working with environmental organizations and individuals, they have been encouraging communities there to instead plant trees and launch eco-tourism enterprises. That’s good news indeed for the monarchs.

Two butterflies take off from a log in this fantastic picture from photographer Dan Osipov. “The monarchs in the colony were quite active, thanks to plenty of sunlight,” says Osipov of this group, which were wintering in the Transvolcanic mountain range in Mexico.

“The monarch is a butterfly ruled by the sun,” continues Osipov. “When the autumn sun reaches fifty two degrees above the horizon, [the] monarch reproduction cycle shuts down, and migration is kicked off. The generation that flies to Mexico has never been there, yet they’re able to find the exact spot year after year where their grandparents spent the winter.”

You could almost call this a cascade of butterflies – arranged as they are on a hanging tree branch. “With the faint suggestion of sunshine, a few monarch butterflies spread their wings in hopes of catching a bit of warmth,” says photographer Douglass Moody, describing the scene. He took this picture at the monarch wintering area of Corona Butterfly Preserve in California.

These butterflies – arranged on a branch like a bunch of grapes – were photographed at the Pismo Beach Monarch Grove in California. Interestingly, not every generation of monarchs migrate. Some simply remain in their breeding ground. Those that do migrate are born at the end of summer or early autumn. Because of their trip to warmer climes, this special generation will outlive several younger generations that stay put. It will then be the migratory monarchs’ great grandchildren that follow the beat of their forebears’ wings.

This stunning shot gives us a closer look at those lovely two-toned wings. Monarch butterflies' wings measure around 3.5 to 4 inches across, with the males slightly bigger than the females overall. The black lines on a male’s wings are also less pronounced than on the females, and the males have an additional black spot in the center of the hind wing that disperses hormones.

Both male and female butterflies have pretty white spots on the black sections of their wings as well as on their bodies. While most monarchs have orange wings, some can be grayish white instead – although this is very rare except in Hawaii.

Here’s another close look at those magnificent wings, this time on some butterflies stopping over in Nebraska on their way south. Monarch butterfly wings are actually water repellent, so not only are they not bothered by a bit of rain; they can even land temporarily on water.

Although these butterflies have six legs, they only really use four of them, holding the front two against their bodies. Incidentally, the monarch caterpillar is also strikingly colored, with a body striped in yellow, black and white.

The pretty butterflies lined up on this willow branch were snapped in Ontario, Canada, in their summer home. It’s thought that the distinctive bright coloring of the monarchs acts as a warning to predators to stay away. Monarch butterflies are also poisonous and will make any animal that tries to eat them sick – hopefully sick enough not to try snacking on them a second time! The poison comes from the milkweed that they eat while they are caterpillars. This doesn’t always work, however. Certain bird species, for example, have learned that some parts of the butterflies are not as toxic, while other predators are resistant or immune to the poison altogether.

Here’s another branch full of delicate wings, this time at the Ardenwood Historic Farm in California. These dazzling orange creatures actually start out as creamy white eggs lain on the underside of milkweed leaves. Once the new baby caterpillars emerge, they first eat their own eggshells, and then the leaves to which they’re attached. Monarch caterpillars stick to this leafy diet, except when they’re munching on their own molted skin as they grow. Now, that’s self-sufficiency!

After that, the caterpillar uses silk spun from its behind to attach itself to a branch, hangs it head down, and molts one last time, leaving a layer of skin that dries and hardens. This is the green-colored chrysalis that will soften and become transparent 10 to 12 days later, allowing the butterfly to emerge.

Photographer Tony Le captured these butterflies at Monarch Grove in California. “In the cold morning hours, I could hardly tell where they were at,” he says; “they were so high up the trees and in the shadows. With just the underside of their wings showing, they looked like dead clumps of leaves.” Pretty beautiful leaves, though, you’ll have to admit.

In this picture, the butterflies could be some kind of overgrown strangling vine, so completely have they covered these branches in their wintering habitat. Scientists are not yet completely sure how the migratory butterflies know to return to the same area each year, as they are separated by several generations from those that were there the season before. The latest research suggests that they can use the Earth’s magnetism to orient themselves as well as following inherited flight patterns.

These days, there are several threats to monarch butterflies. For one, the milkweed they require for sustenance during the caterpillar stage is decreasing due to development. Scientists are also worried that natural disasters in their Mexican wintering grounds and the effects of climate change may have further reduced their numbers. However, efforts are being made to conserve these amazing insects, so that in years to come they will continue to make their incredible journey across the country.


Popular Posts