Liza Gross reported that Ms Dara Satterfield, a doctoral student at the University of Georgia, witnessed scores of Monarch butterflies from the south, like most other Monarchs from breeding grounds in northern United States and Southern Cananda, made a stop in Texas to feast on frostweed to build up their reserves to make their last flight to central Mexico for five months of overwintering.
"Less than 20 years ago, a billion butterflies from east of the Rocky Mountains reached the oyamel firs, and more than a million western monarchs migrated to the Californian coast to winter among its firs and eucalypts."
In 2013, the numbers reached rock bottom in the Midwest and Mexico with about 80-90% drop in numbers. Although the numbers in the fall of 2014 appeared to be encouraging, both Ms Satterfield and Ms Sonia Altizer, an ecologist at Georgia and Ms Satterfiled's adviser, were cautious not to be too hopeful that the good numbers represented a recovering migration. In fact, they were concerned that the well-meaning efforts of butterfly lovers may be accountable for the monarch's current plight.
In a typical year, the first generation Monarch butterflies fly from Mexico to the Southeast when spring approaches and the native milkweeds start to grow. By fall, when the milkweeds die back, up to two more generations of sexually immature Monarchs develop. That is when they make the flight back to Mexico to avoid the approaching winter before the cycle repeats.
The Monarch butterfly's life cycle is intricately synchronized with the native milkweed species such that their migratory patterns are split amongst several generations. The exotic tropical milkweed is now widely used, over the native species, by amateur conservationists to replenish declining populations of milkweed in an attempt to raise the butterfly populations, which may bring about unseasonal breeding, increase the butterfly's exposure to diseases and lead to reproductive failure.
It is reported in the 2012 journal Insect Conservation and Diversity that 60% of native milkweeds disappeared over a span of 10 years between 1999 and 2009. This was documented to be the result of increased applications of Roundup, a broad spectrum Glyphosate systemic herbicide, used to control weeds amongst commercial crops such as corn and soybean, which are genetically engineered to tolerate the weedkiller. Whilst the native milkweeds die, they are replaced by the tropical milkweeds where the migrating Monarchs lay their eggs and spread the spores of an obligate protozoan parasite Ophryocystis elektroscirrha (OE), which was discovered in Florida in the 1960s, that infects the Monarch and Queen butterflies by killing foraging caterpillars or affecting the adults' ability to fly or reproduce normally, thereby reducing their survival rates and fitness.
However, some optimists are positive that the tropical milkweeds make up only a small fraction of all the milkweeds available in the landscape and are hopeful that the Monarchs have sufficient native milkweeds in the abundant landscape of Eastern U.S. to feed when they return in spring.
Meanwhile, Ms Satterfield is continuing her research work on tracing the migratory breeding of Monarchs at tropical milkweed sites to determine if they have abandoned their migratory patterns and hopes to be able to do her part to protect the great North American journey of the Monarchs while there is still hope.
Dragonflies may be the best hunters in the animal kingdom.
I read somewhere that dragonflies are one of the insects that existed eons ago with possibly the dinosaurs and according to this article written by Natalie Angier, these aerial dainty but deadly predators are such effective hunters that they are able to snatch their flying preys 95% of the time compared to about 25% in African lions or 50% in great white sharks. Their voracity and brutally are almost unmatched in the animal kingdom. The preys are often torn up, mashed and consumed before the dragonflies alight on perches.
What is so unique about them is their elaborately designed brain, eyes and wings that enable them to single out their prey in a cloud of other flying insects, track the moving prey through a plotted trajectory and intercept the target in midair. Such ambush predation often catches the clueless prey from behind without them realizing what hit them until it is too late.
Their nervous system shows a capacity for selective attention, much like that of humans, with an intricate network of neurons connecting its brain to its thoracic flight motor center. In most insects, the wings and the thorax are fused and move as one but in the dragonfly, each of the four wings are attached to the thorax through independent muscles, rendering the creature with this almost unheard of extraordinary ability to execute an entire range of flight options which includes hovering, diving, flying backwards and upside down and pivoting 360 degrees in midair with wing beats up to 50 km/h. In addition, their pair of large spherical orbital eyes consist of about 30,000 pixel-like facets and are the largest in the insect kingdom.
In comparison to some other animals and insects, dragonflies have little or no hearing abilities, with short antennas which are ineffective for smelling or pheromonal flirtations.
With such specialized anatomy and unparalleled abilities, it is no wonder the United States military is carrying out research on it as the archetypal precision drone.
Today's weather - sunny
I read an interesting article "Ecosystems that thrive in Amazon's High Places" on page 13 in The New York Times in this morning's TODAY.
Tepuis, which are known as tabletop mountains because of its flat plateau and steep cliff faces, located in the northern Amazon rain forest emerge thousands of meters from lowland forests and support a high biodiversity of flora and fauna such as lizards and frogs. Like mountains in the sky, it is a natural wonder how these are formed in the first place and how the animals get up there.
Unlike the formation of natural mountains such as the Andes which result from the collision of continental plates 25 million years ago, tepuis were hypothesized to form about 70 million years ago as layers of rock with sand at the ocean bottom were raised to become dry terrestrial land and over time, erosion removed the sand and exposed the rock beneath. Interestingly, it was found that the many faunal species living atop the tepuis are not found anywhere else and yet appeared to be closely related to each other, bringing forth the conjecture that they may share a common ancestral lineage.
According to recent research studies on 4 species of tiny tree frogs that live on these tepuis, evolutionary biologists are able to use their DNA molecular clock and compared them to their closest lowland relatives to determine how long ago their common ancestor existed before it accumulated new mutations and diverged into separate species. It was discovered that the common ancestor of these 4 frog species lived about 5.3 million years ago, and not 70 million years ago. This means there is a possibility that the frogs scaled up the colossal cliffs to the tepuis and became separate species only several hundred thousand years ago.
Unfortunately, global warming has driven the mountain-dwelling species to higher altitudes but they can only go as far and as high as the top of the tepuis. I am ending this post with a quote from Ms Patricia Salerno, the lead evolutionary biologist, from the University of Texas, involved in the study:
"The tepui frogs may have been able to scale cliffs that would make mountaineers blanch. But even they can't climb into thin air."
Today's weather - sunny
After watching "Avatar", who doesn't know Sam Worthington? His latest movie "Man on a Ledge", stars Elizabeth Banks, Jamie Bell and Ed Harris etc.
Driven to desperation, a former police officer and now innocent fugitive Nick Cassidy on the run from the law decided to pick a crowded traffic junction in New York City to attempt suicide by jumping off a tall building. But things were not as simple as it seemed and cops were also involved in the crime.
The truth was, Nick didn't want to die. He staged this suicide attempt to draw media attention to his act, in a bid to clear his name, while his brother and girlfriend were across the street in a jewellery vault stealing a $40 million diamond, for the first time, from the businessman who framed him for stealing the diamond and landed him in jail for a crime he didn't commit. Well, the premise is if the diamond was reported as stolen, then he couldn't go to jail for stealing something that was supposedly missing.
It is not the blockbuster kind of movie and didn't pack in the crowds although I feel it is passable. At least I got to watch the trailer for the upcoming "Avengers" movie starring Captain America, Thor, Incredible Hulk, Iron Man and so on.
