The harsh conditions of the tundra are no match for the hardy Arctic springtail. (Photo credit: John Schwieder/Alamy)

The Arctic springtail (Megaphorura arctica), also referred to as a “snow flea,” is a small, wingless insect that lives in the Arctic tundra. This animal gets its name from its ability to catapult itself using a rigid tail that typically remains folded underneath its body and releases in the face of danger. However, in general, the springtail moves from one place to another by crawling.

The Arctic springtail lives in damp, boggy habitats and feeds on organic waste on the forest floor. One of the more interesting features of the Arctic springtail is its ability to survive the freezing temperatures of an Arctic winter. Before periods of extreme cold set in, the springtail dehydrates itself into a small husk. When warmer temperatures arrive, the springtail rehydrates itself and resumes normal activities. This method of survival is called “cryoprotective dehydration.” Other animals that use this survival method include an Antarctic nematode, an enchytraied worm, Antarctic midge larvae, and the cocoons of a certain species of earthworm.

During the process of cryoprotective dehydration, water is lost from the springtail’s body across a diffusion gradient between the animal’s super-cooled body fluids and the ice in its surroundings. At a certain point, the springtail loses enough water from its body that its body cannot freeze and it enters a state of metabolic activity suspension.

The Arctic springtail looks quite similar to its southern cousin, the Antarctic springtail ( Cryptopygus antarcticus), pictured here. Magnification unknown. (Photo credit:British Antarctic Survey / Photo Researchers, Inc.)

Recently, scientists conducted a research study to better understand the genetics behind the process of cryoprotective dehydration in Arctic springtails. The study was led by Melody Clark of the British Antarctic Survey (BAS) and featured contributions by her colleagues at the BAS and faculty members of the University of Novi-Sad in Serbia.

For their study, the scientists created 6,912 Arctic springtail clones in order to examine the processes and genes involved in this survival method. The researchers studied the springtails’ response to cold- and salt-induced dehydration. They found that cold-induced dehydration was connected with the movement of trehalose, a natural antifreeze contained in the springtails’ body. Trehalose protects cellular systems and tissues from freezing. When conditions were returned to normal, the springtails’ recovery process was marked by the activation of genes involved in energy production, leading to protein production and cell division.

This research is part of a larger project focusing on determining how different species of animals survive desiccation. Scientists are interested in studying this phenomenon as understanding how it works may prove useful in the development of processes and technology related to human medicine such as preserving tissues for transplants.

The results of the scientists’ study were published online in the July 21, 2009 edition of the open-access journal BMC Genomics. In addition to study author Melody Clark, other researchers who contributed to the report included Michael A. S. Thorne, Jelena Purac, Gavin Burns, Guy Hilyard, Gordana Grubor-Lajsic, and M. Roger Worland.

More to Explore

• Genes that let creepy-crawlies survive a deep freeze
• Surviving the cold: molecular analyses of insect cryoprotective dehydration in the Arctic springtail Megaphorura arctica (Tullberg).
• Springtail Fact Sheet
• Biological identification of springtails (Hexapoda: Collembola) from the Canadian Arctic, using mitochondrial DNA barcodes
• Strategy: Dehydration helps survive freezing: Arctic springtail
• Seasonal Adaptations in Arctic Insects

Bark beetles, tiny insects the size of a grain of rice, are behind the demise of western pine forests. Bark beetles have hard, cylindrical bodies that are typically red, brown, or black in color. There are 600 different species of bark beetles in the United States. Not all species of bark beetles attack trees; some just live within the bark of already-dead or dying trees. Two species of special concern that do attack trees are the mountain pine beetle (Dendroctonus ponderosae), which attack lodgepole pine and sugar pine trees, and the western pine beetle (Dendroctonus brevicomis), which attack coulter pine and ponderosa pine trees. (The term “dendroctonus” means “tree killer” in Latin.)

The tiny bark beetle is only about as big as the head of a matchstick. (Photo credit: US Global Change Research Program)

Like most insects, the life cycle of a bark beetle goes from egg to larva to pupa to adult; these changes typically occur over a period of a year. At higher elevations, where temperatures are normally cooler, bark beetles tend to have a two-year life cycle. The bark beetle’s life cycle begins when a female burrows into the bark of a tree, where she builds an “egg gallery.” During the summer or early autumn, the female lays her eggs along the sides of the gallery. After a period of 10 to 14 days, the eggs hatch. The newly-hatched beetles remain larvae for about 10 months. Larvae spend this stage of their life within the tree bark, where they feed on the tree’s phloem. Following their development from pupa to adult, the beetles bore a hole through the tree’s bark and leave the tree. After emerging from the tree, the adult bark beetles move to other trees, and the cycle begins again.

Though their feeding on a tree’s phloem is harmful, the bark beetles themselves are not the ultimate cause of a tree’s death. A major agent of tree death is blue-stain fungus. The bark beetles carry this fungus on their bodies. Once introduced to the tree, the blue-stain fungi spread throughout the tree and interrupt the flow of phloem to the tree’s crown. The fungi also decrease the flow of pitch (thick, sticky pine sap) through the tree, which reduces the tree’s defenses against bark beetle attack. (Most healthy trees are able to survive an attack by bark beetles by throwing out large amounts of pitch, which drowns the beetles.) In addition to killing trees, blue-stain fungus, as its name implies, stains the sapwood (outermost wood) of a tree blue.

Conifer forests in the western United States have been particularly hard-hit by bark beetle outbreaks. A total of over seven million acres have been affected in the United States. Of this acreage, one million acres have been affected in Montana and 1.5 million acres have been affected in Colorado and Wyoming. In 2002, the U.S. Forest Service estimated that over the next 15 years, bark beetles could affect nearly 22 million acres of western forestland. Canadian forests (particularly those located in British Columbia) have had it even worse—over 34 million acres have been lost because of bark beetle attacks. Initial signs of tree death include red or orange needles at the crown (or top) of a tree; by the time such signs are present it is too late to save the affected tree. Though it may be distressing to see large swathes of dead or dying forestland, a larger concern is what happens to the forest after the trees die. Many forests are being clearcut due to the large amount of dead trees. This management practice is done to prevent devastating crown-based wildfires. Fire is also a concern for trees that have fallen to the ground. Wildfires at ground level can bake the ground, which severely damages soils, prevents regrowth, and may lead to devastating erosion and mudslides. Standing dead trees are also a cause for concern, as they may fall at any time. This is particularly worrisome in heavily trafficked sites, such as campgrounds and other recreational areas.

The bark of this lodgepole pine shows evidence of bark beetle infestation. (Photo credit: Wave Royalty Free/Photo Researchers, Inc.)

Once bark beetles have attacked a tree, there is no effective method to save the tree. The best time to prevent the spread of bark beetles is either before an attack has occurred or after a tree has succumbed to an attack. Trees that are particularly vulnerable to bark beetles are old trees and unhealthy or stressed trees. Scientists think that the current bark beetle outbreak is particularly severe because of an ongoing drought in the western United States. Watering trees in order to prevent drought-induced stress can help keep trees healthy and make them less vulnerable to a bark beetle attack. Researchers have also found that certain insecticides, if applied to trees prior to an infestation, can also help prevent trees from being attacked by bark beetles.

For trees that are already infested or dead, forest managers recommend that the affected limbs be removed or the entire tree felled. Removed branches or trees should then be destroyed, either through burning or chipping. Another option is to pile cut wood in an area that receives direct sunlight and tightly cover the woodpile with a plastic sheet. The trapped heat kills any bark beetles still in the wood as well as dries out the wood, making it unsuitable as a bark beetle food source. Trees that are cut down due to bark beetle infestation do not go to waste. Cut lumber can be used as firewood, in biomass boilers, as a source of pellets for woodstoves, as newsprint, and as material for furniture or home construction.

One thing to remember is that bark beetle outbreaks are not abnormal events in and of themselves. In fact, even the loss of lodgepole pine forests is not shocking—lodgepole pines have evolved to go out with a stand-replacing event, though the cause is typically fire. In this case, bark beetles are taking the place of fire—when they attack and kill older trees, they allow younger tree species to take over. There are other benefits to the current bark beetle attack as well. As dead trees decompose, they add nutrients, including nitrogen, to the soil. Openings in the forest also let other trees grow at a faster pace as they are able to receive more sunlight to fuel photosynthetic activities. Fallen and standing dead trees also provide habitat for animals and other organisms.

Though bark beetles themselves are a normal part of western forest habitats, the severity of the current outbreak, however, is unusual. Scientists studying the current bark beetle infestation point to several factors that may explain why the infestation has lasted for so long. One major factor is the policy of suppressing forest fires. Fire is a natural part of a forest’s life cycle. A long-standing policy of fire suppression has led to the development of stands of trees that are all relatively the same age and same size. Forests that contained a mosaic of tree ages and sizes were historically able to quell bark beetle attacks as the beetles tended to be unable to move through the diverse forest stand. Also, as discussed above, continuing drought conditions have weakened trees to the point where they are unable to stave off an attack by bark beetles.

Climate change is also identified as another culprit behind the strength of the current bark beetle attack. A warmer climate has led to warmer winters, which helps bark beetle populations flourish. A warmer climate is also helping bark beetles extend their ranges into new territories. In general, climate change is causing bark beetles to act like an invasive, non-native species. The beetles are now able to attack trees at higher elevations and are now even going after younger and healthier trees than they would typically attack.

In the future, the composition of conifer forests may be drastically different than what they look like today due to the influence of bark beetles. (Photo credit: US Global Change Research Program)

Given the severity of the current bark beetle outbreak, foresters are working on the development of a management plan to deal with the massive amount of affected trees in western forests. The Western Forestry Leadership Coalition (WFLC), a partnership of state and federal foresters, was created in part to answer management issues such as these that involve many agencies and cross multiple boundaries. The WFLC recommends a four-pronged approach to the management of forest impacted by bark beetles. First, they recommend prevention through the use of forest-thinning techniques. Second, they recommend the suppression of bark beetle activities through the removal of affected trees, the use of pheromone-baited traps to capture bark beetles, and the use of pesticides. Third, they recommend active restoration of particularly hard-hit forests or high-value forests (such as those that provide habitat for endangered species). Fourth, and perhaps most importantly, the WFLC recommends continued research and public outreach to better understand the current outbreak and how it might be curtailed and inform the public as to what is happening to the region’s iconic forest regions.

Clearly, over the next several years, western forests will change. The species composition and density will also change over time, as normally occurs during the natural process of succession. In the end, the bark beetle-pine tree relationship is a natural one that has occurred for thousands of years. Though its results may be devastating to see, it is a gentle reminder that nature is not always pretty.

More to Explore

• Western Bark Beetle Assessment: 2009 Update
• Pests in Gardens and Landscapes: Bark Beetles
• Pine Bark Beetles Affecting More than Forests
• Biology, Ecology and Management of Western Bark Beetles
• Rocky Mountain Region Bark Beetle Information
• Mountain Pine Beetle Leaflet
• Our Future Forests
• Bark Beetles Kill Millions of Acres of Trees in West
• Some See Beetle Attacks on Western Forests as a Natural Event

Red patches in this forest indicate devastation from the bark beetle. (Photo credit: US Global Change Research Program)

Bristlecone pines, such as those growing in the White Mountains, are extremely long-lived organisms. (Photo credit: Stephen Saks Photography/Alamy)

Talk about tenacity—not only are bristlecone pines among the oldest organisms alive, but they also survive in rather harsh conditions. These long-lived organisms have a number of interesting adaptations that allow them to survive over long periods of time in what many other organisms would consider to be rather hostile conditions.

Natural History

Two species of bristlecone pine live in the United States: Pinus longaeva and Pinus aristata. Though originally considered to be just one species (P. longaeva), further investigation by scientist Dr. Dana K. Bailey in the 1960s indicated that genetic and structural differences within the species were significant enough to warrant dividing the bristlecone pine into two separate species. P. longaeva, commonly called the Great Basin bristlecone pine, are found in California, Nevada, and Utah. P. aristata, also known as Rocky Mountain bristlecone pine, has populations in Colorado and Arizona. The most long-lived bristlecone pines belong to the P. longaeva species, and the oldest known bristlecone pine is found in California's White Mountains.

Bristlecone pines get their name from the long prickly bristle found at the end of each scale on the tree's cones. These pines can be identified from other conifers by their needles, which are one inch in length and grow in bunches of five. The needles completely surround the tree's branches. Like other conifers, bristlecone pines reproduce through their cones. The tree's cones start out deep purple in color and as they mature over a two-year period they turn brown.

Immature cones are purple, as the cones mature they turn brown in color. (Photo credit: Dennis Flaherty/Photo Researchers, Inc.)

Habitat

The most studied population of ancient bristlecone pines is found in the White Mountains in the Inyo National Forest. Among the population of bristlecone pines that live here is the famed Methuselah tree, which has been dated (using dendrochronology techniques) to an age of over 4600 years old.

The Methuselah tree and other bristlecone pines found in the White Mountains live in particularly harsh conditions. First, many are found at high elevations (up to 3470 meters (or over 11,000 feet). At such high elevations, little vegetation exists. The oldest known bristlecone pines grow here on a rocky alkaline soil made up of dolomite, a type of limestone. Because little else is able to survive on such alkaline soil, bristlecone pines are able to survive here relatively competitor-free. Another factor that makes life more difficult for bristlecone pines is the climatic conditions at high elevations which are particularly cold and dry. Such harsh conditions drastically limit the bristlecone pine's growth. Because these trees grow at such a slow rate, their wood is particularly dense. This dense and highly-resinous wood makes it basically impenetrable to attacks by bacteria, fungus, or insects. With such dense wood and little other vegetation in the area, these trees are also protected from fire events.

Contribution to Science

In addition to their other fascinating attributes, bristlecone pines have even contributed to science. In the 1960s, scientists discovered that the radiocarbon dating process was flawed. Given that scientists could precisely determine a tree's age by counting its rings, scientists were able to calibrate the radiocarbon dating method by comparing a tree's known age with the amount of carbon-14 in samples from the same tree. In doing so, the scientists found that radiocarbon dating routinely underestimated a sample's age. With the help of the bristlecone pine samples, the scientists were able to calculate a calibration factor to account for this underestimation and thus correct the dating process.

More to Explore

• Inyo National Forest: Bristlecone Pine Forest
• Bristlecone Pine
• Methuselah Tree: A Tree's Secret to Living Long
• Identifying Bristlecone Pines

Such a scene may evoke thoughts of the African savannah and its wildlife inhabitants. However, the animal depicted lives much closer to home – and can be found in over 38 million American households. The animal in question is Felis domesticus or the domestic cat, and like its African relative, can have quite a significant effect on local wildlife populations when left to roam freely outside.

Pet cats that live outdoors can wreak havoc on native songbird populations. (Photo credit: Steve Vates/Alamy)

According to a study conducted by the American Pet Products Manufacturers Association (APPMA) in 2007, 34 percent of the United States population owns at least one cat. Cat ownership is highest in rural areas, where up to 60 percent of the population count cats among their household members. It is these rural populations of free-roaming cats that can have the most devastating impact on native wildlife species.

Cats, known to be skilled hunters, not only affect wildlife numbers directly by predation, but also indirectly by preying on the animals that serve as a food source for naturally occurring predators. In addition, cats can spread disease to other species. In a study published in the Journal of Wildlife Diseases in 1993, cats were listed as culprits in the spread of feline distemper and Feline Immunodeficiency Virus (FIV) to populations of the endangered Florida panther.

According to a study conducted by researchers at the University of Wisconsin, outdoor cats can be implicated in the killings of hundreds of millions of birds and perhaps a billion small mammals each year. Rural cats have the most impact, as 90 percent of their diet is dependent on wildlife.

Predation by cats has led to the extinction of several bird species, and is particularly devastating to nesting shorebirds and island seabird populations. Introduced onto islands as both a way to combat rats (also human-introduced, albeit inadvertently) and as pets, cats took to hunting the native bird species, which were not adapted to such predators. On the islands of New Zealand alone, cats were responsible for the extinction of eight bird species. Within the U.S., bird species considered to be particularly susceptible to cats include ground-nesting shorebirds whose populations are already in decline, and the endangered California Quail, a species known to be targeted by cats as prey.

In response to these impacts, several conservation organizations have become involved in education programs to encourage cat owners to keep their pets indoors. One such program is Cats Indoors!, developed by the American Bird Conservancy and promoted by the Audubon Society. The campaign has been in place for twelve years, and its tenets have been adopted by the states of Florida, Hawaii and Minnesota, as well as the Department of Defense and Outer Banks National Seashore.

“Our citizen education program has thousands of activists across the country who are conducting education campaigns, getting local ordinances passes, trapping stray and feral cats themselves, and fighting efforts to legalize trap/neuter/release efforts in their communities,” Cats Indoors! campaign director Linda Winter said.

Rural housecats and feral cats pose an even greater problem to wildlife due to their sheer numbers and their often complete reliance on wildlife for their diet. According to Dr. Jo Liska, director of educational programs for the Bloomington (Indiana) Animal Shelter, these cats potentially pose a danger to themselves and others around them.

“There is a prevalent mentality, especially in rural areas, that cats should be free to roam, and one doesn’t really care if they are not seen for awhile,” Liska said. “Generally, those cats are also intact, not vaccinated, and not tested for FIV/FeLV [Feline Leukemia Virus]. This endangers all cats who spend any time outdoors and unsupervised.”

Keeping cats indoors helps to ensure good health and protects small bird species that live in your neighborhood. (Photo credit: Mark Scheuern/Alamy)

Among the guidelines suggested by the Bloomington Animal Shelter include keeping cats indoors, spaying or neutering, keeping vaccinations complete and up to date, and testing for FIV/FeLV. Aside from preventing potentially devastating impacts on wildlife species, keeping cats indoors is also in the pet’s best interest.

“Indoor cats live an average of 15 years, while outdoor cats live a mere three to five,” Dr. Liska said. “The latter are subject to acts of cruelty, to predation by coyotes, dogs, skunk, et cetera, to vehicles, to disease, to starvation, and to inadvertent poisoning.”

Providing outdoor cats with food does little to decrease their impact on native species in the wild because their hunting instinct is not driven solely by hunger. The most effective solution is to prevent them from having the opportunity to hunt outdoors.

“Outdoor cats take their share of wildlife, especially birds, even if they are well-fed,” she said. “They are natural predators simply doing what is hard-wired behavior.”

More to Explore

• Cats Indoors! The Campaign for Safer Birds and Cats
• How to Make Your Outdoor Cat a Happy Indoor Cat
• Give Birds a Break. Lock Up the Cat.

Do you know what your cat is up to when it's outside? (Photo credit: Steve Vates/Alamy)

A male Anna's hummingbird is distinguished by a ruby red patch on its chin and head. (Photo credit: Tim Zurowski/All Canada Photos/Alamy)

Male Anna’s hummingbirds (Calypte anna) have quite an impressive courtship display to impress the ladies. When the male spies a female during the breeding season, it proceeds to soar 30 meters up into the sky and then dives down toward the female, reaching speeds up to 27.3 meters per second (61 mph) at the peak of its dive. As the male hummingbird pulls out of the dive by outstretching its wings, it experiences forces more than nine times the force of gravity. As the study’s author points out, these same G forces would cause a trained fighter pilot to black out due to a rush of blood away from the brain. Luckily, the G forces do not have the same affect on the diving Anna’s hummingbird.

In studying the hummingbird’s nose-diving courtship behavior, Christopher Clark, a Ph.D. student at the University of California-Berkeley, enticed males by setting out a caged or stuffed female Anna’s hummingbird in an area where the male could see it. Clark then placed a video camera in the area to capture the male’s flight. In addition to a standard video camera, Clark also used a video camera capable of capturing 500 frames per second.

Clark’s set-up was successful in garnering the interest of male Anna’s hummingbirds. More interested males flew up and dived by the female for a total of 10 to 15 times in a row. One overzealous suitor made 75 consecutive dives, taking only a few minutes’ break.

In recording the hummingbird’s diving activity, Clark observed that the birds flap their wings when first diving, then fold their wings close to their body as they bullet down straight toward the female. The birds outstretch their wings at the base of their dive, heading back upward to make another pass.

In addition to their amazing speed, Clark determined that the hummingbirds also travel at a rate of 385 body-lengths per second. This figure is faster than a peregrine falcon (200 body-lengths per second), fighter jet (150 body-lengths per second), and space shuttle re-entering the atmosphere (207 body-lengths per second). Using this data, Clark concluded that the male Anna’s hummingbird has the “highest known length-specific velocity attained by any vertebrate.”

The results of Clark’s research were published in the June 9, 2009 edition of the British journal Proceedings of the Royal Society B.

More to Explore

• Hummingbird Pulls Top Gun Stunts
• Courtship dives of Anna's hummingbird offer insights into flight performance limits
• Anna's Hummingbird in Flight [video]
• Hummingbird's Faster than Jets
• How a hummingbird in love can move faster than a fighter jet
• The Courtship of Anna's Hummingbird [video]

(Photo credit: Tim Zurowski/All Canada Photos/Alamy)

Turkey is a common sight on Thanksgiving. (Photo credit: Photodisc/Getty Images)

The centerpiece of many Thanksgiving dinners in the United States is a roasted turkey. According to the National Turkey Federation, it is expected that over 273 million broad-breasted white turkeys—the standard turkey found in your local supermarket—will be raised in the United States. This Thanksgiving alone, it is estimated that Americans will consume 46 million turkeys. However, a growing number of small-scale poultry producers across the United States are eschewing modern industrial farming practices and instead are raising unique and rare breeds of turkeys that have been around since the very first Thanksgiving feast in 1621.

An Introduction to Heritage Turkeys

According to the Heritage Turkey Foundation, heritage turkeys were originally bred for fine flavor, beauty, and thriftyness, a quality that referred to the amount of meat produced from the quantity of food fed to the turkey. Turkeys are a quintessential American food—all domesticated turkeys in the United States are descendants of wild turkeys native to North and South America.

There are three criteria a turkey must meet to qualify as a heritage turkey, according to the American Livestock Breeds Conservancy (ALBC). These qualities include the following:

This male turkey (commonly called a 'tom') is an example of the Bourbon Red heritage breed. (Photo credit: Keith J Smith/Alamy)

• The turkeys must reproduce naturally by mating. In order to qualify as a heritage turkey, the turkey must be the result of naturally mating pairs of both grandparent and parent stock.
• The turkeys must have a long productive outdoor lifespan. Breeding hens most be productive for five to seven years. Breeding toms must be productive for three to five years. It is imperative that the turkeys have the genetic ability to withstand the rigors of living outdoors.
• The turkeys must have a slow, natural growth rate. The birds should reach marketable weight in about 28 weeks. This long period of growth lets the birds develop strong skeletal structures and healthy organs prior to putting on muscle mass.

There are a number of different breeds of heritage turkeys. Many of the turkeys were originally bred for qualities such as productivity or specific color patterns. Among the breeds that are named by the American Poultry Association as standard breeds are Black, Bronze, Narragansett, White Holland, Slate, Bourbon Red, Beltsville Small White, and Royal Palm. Two other popular varieties of heritage turkeys include the Jersey Buff and White Midget. Over the past ten years, populations of heritage breeds of turkeys have been on the rise. According to Marjorie Bender, ALBC research and technical program director, in 1997 there were 1328 breeder birds; just three years ago, that number had grown to 10,404 breeder birds. Though most heritage turkey breeds are still endangered, there populations are much more secure than they were ten years ago.

Comparing Heritage Turkeys to Standard Turkeys

Over 99 percent of the turkeys raised in the United States are of the broad-breasted white variety. (Photo credit: INSADCO Photography/Alamy)

What makes heritage turkeys different from the standard turkeys you might find in your local supermarket? The standard turkey you most often find in the supermarket is a breed called the broad-breasted white turkey. These turkeys have been bred to provide a large amount of breast meat. Because of their abnormally large breast-size, the turkeys are unable to reproduce naturally. Instead, artificial insemination is necessary. Without human intervention, these turkeys would go extinct after just one generation.

In addition, while heritage turkeys must be free to roam, most broad-breasted white turkeys are raised in confined conditions. Due to these confined conditions, the turkeys are given antibiotics and other supplements to prevent the spread of disease. Heritage turkeys are certified antibiotic-free. The diets of both types of birds are also different. Since heritage turkeys are allowed to roam freely in the outdoors, they feed on a natural diet of insects, seeds, and grasses. Industrial turkeys are fed a steady diet of grains. According to research conducted by the USDA Sustainable Agriculture and Research Education Program, meat from turkeys that spent some portion of their lifetime outside had 21 percent less total fat, 30 percent less saturated fat, 28 percent fewer calories, 50 percent more vitamin A and 100 percent more omega-3 fatty acids.

One of the biggest differences between a standard turkey and a heritage turkey is the length of time it takes for each to reach maturity. Standard turkeys reach an average weight of 32 pounds over a period of 18 weeks. This length of time to maturity is 10 weeks earlier than it takes for heritage turkeys to reach maturity. To put this value into perspective, a market-ready standard turkey is the equivalent of an 11-year-old child weighing 300 pounds.

Drawbacks and a Look to the Future

One of the benefits of industrially-raised turkeys is their low cost in the marketplace. Raising a large amount of turkeys in a small space under standardized conditions lets producers sell them at the supermarket for a lower price. Because heritage turkeys require more space and take longer to grow to maturity, they are more expensive to raise. This added expense is passed on to the consumer. Compared to a standard supermarket turkey, heritage turkeys are often exponentially more expensive.

Because most heritage turkeys are produced by small-scale farms, they are often fairly difficult to procure. Most heritage turkeys are accounted for long before the Thanksgiving holiday. Although the production of heritage turkeys remains a niche industry, a growing interest in organic and sustainably-produced food products is helping to bring the breeds to the forefront. Without the farmers' intervention, many of the breeds of heritage turkeys would go extinct. By continuing to raise these rare and unique breeds of turkeys, poultry farmers help to maintain the genetic diversity of turkey species.

"Endangered breeds are a significant part of biological diversity in agriculture," Ms. Bender said. "These breeds are important to conserve because they provide options for the future. Agriculture will change, [and] the animals will be able to meet the new demands only if we assure their survival."

More to Explore

• Definition of a Heritage Turkey
• American Livestock Breeds Conservancy
• Heritage Turkey Foundation
• National Turkey Federation

A small but growing number of farmers are raising rare and unique varieties of turkeys referred to as heritage turkeys. (Photo credit: Keith J Smith/Alamy)

Didymo covers rocks and twigs at the bottom of a waterway. (Photo credit: S. Spaulding / U.S. Geological Survey)

Didymosphenia geminata is a single-cell alga commonly referred to as rock snot due to its grayish-brown color and clumpy appearance. This alga also goes by the name "didymo" for short. Though it looks slimy, it actually only feels like wet cotton or wool.

While many species of algae float on top of the water surface, didymo instead clings to rocks in river bottoms and other waterways. What starts as a few dots on a rock eventually turns into a massive clump of algae that remains attached to the rock’s surface by a stalk. The free ends of the alga float in the water, forming white “rat-tails” that resemble clumpy toilet paper.

One major problem with didymo is that it can form huge blooms without warning. These blooms can have deleterious consequences for native organisms by smothering them. The algal mats that form can also be a major problem for public works when they clog water intake systems.

Research indicates that didymo can be spread from one waterway to another by contaminated fishing equipment. Felt-soled waders worn by fly fisherman and other fishing enthusiasts are of particular concern. Studies indicate that Didymo can survive for a period of at least 24 hours outside of water. If they remain in a damp and cool environment, the alga can survive for up to 90 days. The use of felt-soled waders has been banned in New Zealand. Didymo was first discovered in a stream in New Zealand in 2004, and has since spread to over 120 rivers and streams in the country’s South Island. Protecting the country’s waterways from infiltration by didymo is a high-priority in New Zealand; anyone convicted of knowingly transferring didymo from one waterway to another may face up to five years in prison and/or a fine of up to $100,000.

Didymo is a major problem in New Zealand waterways. (Photo credit: David Newton / Alamy)

In the United States, fishers are encouraged to use rubber-soled waders. Fishers are also encouraged to check their equipment before they leave the fishing site to remove any visible pieces of algae. Afterward, they should let their equipment dry completely before entering any other waterway with it. If this is not possible, officials with the U.S. EPA encourage sportsfishers to dip their fishing equipment into a solution made of bleach and water to sanitize their equipment and kill any didymo cells.

Thus far there is no recommended method to remove or kill didymo in affected waterways. Scientists in New Zealand tested one potential control agent but found its use was not yet warranted and required further study. It is in the best interest of fishers to ensure they do not aid in the spread of didymo, as the algae has been implicated in habitat loss for the very fish the sportsfishers aim to catch. Didymo algal blooms often choke out insects such as stoneflies and worms that species such as trout depend on as a food source. Reducing the spread of didymo will help ensure that adequate habitat is available for these species of game fish.

More to Explore

• An Unsightly Algae Extends Its Grip to a Crucial New York Stream
• Didymo: a nuisance and invasive freshwater alga
• Distribution Map of D. geminata in North America
• Didymo Species Profile
• Introduction to Didymosphenia geminata (Didymo) [video]
• Biosecurity New Zealand: Didymo

Given its clumpy and slimy appearance, D. geminata is commonly referred to as "rock snot." (Photo credit: S. Spaulding / U.S. Geological Survey)

Estimates indicate there are 1400 wild tigers in India. (Photo credit: James Warwick / Getty Images)

Given a tiger’s large territorial range, solitary behavior, and mainly nocturnal activities, tracking the animal is a difficult endeavor. Wildlife researchers in India have determined that collecting fecal samples (also known as scat) is a reliable method that can be used to determine the population size of tigers in the wild.

The largest population of wild tigers is found in India. Using a combination of paw print and camera trap evidence (wherein individual tigers are identified by their stripe patterns), wildlife biologists estimate the population of wild tigers in India to be around 1400 individuals. Given this small overall population size, the tigers are listed as an endangered species. The two main threats tigers face are habitat destruction and poaching. Tiger bones and other body parts are a key ingredient in many traditional medicines used by the Chinese and other Asian cultures.

Traditionally, scientists have used individual paw prints to calculate tiger population size. (Photo credit: Martin Harvey/Corbis)

Separate studies have indicated that collecting scat is a good way to measure the population and distribution of animals such as penguins, wolves, and bears. Ullas Karanth, a tiger specialist with the Wildlife Conservation Society’s India program, and his colleagues spent six weeks collecting scat samples over an area of 800 square kilometers in Bandipur National Park. The researchers collected 58 separate scat samples. These samples were brought to the National Centre for Biological Sciences in Bangalore. Once there, Uma Ramakrishnana and her colleagues used DNA in intestinal cells found in the tiger feces to identify individual tigers. Their research indicated that the fecal samples belonged to 26 different tigers. A separate camera trap study identified 29 different tigers in the same area, supporting the DNA evidence of at least 26 different wild cats in the area.

The researchers are looking forward to continuing DNA studies of scat to monitor the tiger population and distribution in India. They believe that DNA identification is an excellent option where setting up cameras is difficult or not feasible at all.

The results of the scientists’ research were originally published in the June 17, 2009 edition of the journal Biological Conservation. Scientists who contributed to the research included Samrat Mondola, K. Ullas Karanthb, N. Samba Kumarb, Arjun M. Gopalaswamy, Anish Andheriad and Uma Ramakrishnana.

More to Explore

• Dung may be key to tracking elusive tigers
• Evaluation of non-invasive genetic sampling methods for estimating tiger population size [abstract]

Tigers, an endangered species, are an elusive subject to study in the wild as they often live solitary lives. (Photo credit: James Warwick / Getty Images)

M. avium subspecies (rod-shaped bacteria stained red). (Photo credit: CDC/ Dr. Edwin P. Ewing, Jr.)

To determine the identities of bacteria living in the showerheads, the scientists collected bacterial samples, isolated DNA from the samples, and used the polymerase chain reaction (PCR) method to identify bacterial species. In addition, the scientists took apart some of the showerheads and used a scanning electron microscope to analyze the showerhead's surface in detail.

According to the researchers, the presence of M. avium and other pathogens in shower water should not be a major cause for concern for most people. Only those with compromised immune systems, such as the elderly, pregnant women, or those with chronic diseases, are particularly vulnerable to M. avium. Common symptoms related to an M. avium infection include shortness of breath, weakness, tiredness, and a dry cough that does not go away.

However, the scientists did provide two suggestions as to how to decrease your exposure to pathogens that may live in your showerhead. First, they suggest allowing the water to run for a few seconds before entering the shower, as the first blast of water from the showerhead typically contains the most pathogens. Also, the scientists suggest switching from a plastic showerhead to a metal showerhead, as they found that metal showerheads commonly harbor fewer bacteria than those made of plastic.

The results of the scientists' research was published online in the September 14, 2009 edition of the journal Proceedings of the National Academy of Sciences. In addition to Dr. Pace, other researchers who contributed to the study included Leah Feazel, Laura Baumgartner, and Kristin Peterson of CU-Boulder and Kirk Harris of the University of Colorado at Denver.

More to Explore

• Daily Bathroom Showers May Deliver Face Full of Pathogens, Says CU-Boulder Study
• Showers May Deliver Face Full of Pathogens [video]
• Showerhead Study FAQs

Because iron supplements or other food sources are not readily available or overly expensive, scientists are working on developing an iron-rich variety of rice. Researchers at the Swiss Federal Institute of Technology Zurich (also referred to as ETH Zurich) have had success in doing just that.

Lead researchers Christof Sautter and Wilhelm Gruissem worked with colleagues to genetically modify a rice plant to increase its iron content. In their experiment, the scientists inserted two plant genes into an existing variety of rice. The two inserted plant genes work together to both mobilize and store iron. In addition, the inserted genes aid in the rice plant's ability to absorb a greater quantity of iron from the soil and also store more iron in the rice kernel. Most importantly, the modified rice plant was shown to have a six-fold increase in iron content compared to a typical (unmodified) rice plant.

More research and experiments, including tests to see whether the modified rice plants will grow under typical agricultural conditions, are necessary before the modified rice plants will be available commercially. Regulations require that genetically-modified seeds and plants must undergo a rigorous period of greenhouse and field testing to ensure that it is safe for human consumption and will not have negative impacts on an ecosystem. In addition, the scientists are interested in increasing the modified rice plant's iron content to at least twelve-fold; that is, twice the level they currently have achieved. Upon the modified rice plants eventual assumed approval, the scientists would like to provide it to small-scale and self-sufficient farmers at no cost, given the crop's humanitarian implications.

More to Explore

• Combating Iron Deficiency: Rice With Six Times More Iron Than Polished Rice Kernels Developed

The research was led by Dr. Anna Kuparinen, a scientist with the ecological genetics research unit in the department of biological and environmental services at the University of Helsinki. Kuparinen and her colleagues analyzed micrometeorological data gathered over a 10-year period by researchers at the Hyytiala Forestry Field Station, located 210 kilometers northwest of Helsinki. Using statistical analysis techniques, the scientists determined that an increase in global temperatures had a positive correlation with increased dispersal of plant seeds and pollen. The scientists also discovered that a temperature change of three degrees Celsius increased the speed at which seeds and pollen were dispersed as well as increased the rate at which plant populations grew.

Research indicates that the long-distance dispersal of seeds and pollen is a key factor in the spatial dynamics of plant genotypes, populations, and communities. As global temperatures increase and seeds and pollen are able to disperse farther, plants may be able to colonize areas where they previously did not exist, helping to ensure their survival in a warming climate.

The results of the scientists' research was published online in the June 10, 2009 edition of the journal Proceedings of the Royal Society B and is found in the September 7, 2009 print edition of the same journal. Other scientists who contributed to the research included Gabriel Katul, Ran Nathan, and Frank M. Schurr.

More to Explore

• Global Warming Increasing The Dispersal Of Flora In Northern Forests
• Increases in air temperature can promote wind-driven dispersal and spread of plants [abstract]

This green roof is found atop a building in Montreal, Canada. (Photo credit: Megapress/Alamy)

A green roof refers to a layer of landscaping placed over the top of traditional roofing materials. A green roof consists of seven different layers (listed from the bottom up):

• roof deck
• waterproof membrane
• root barrier
• drainage layer
• filter cloth
• growing materials
• plants

There are two main types of green roofs: extensive and intensive. Extensive green roofs contain a low diversity of plants, require little maintenance, are low weight, and are relatively low cost. Intensive green roofs contain a high diversity of plants, require more maintenance, are higher weight due to deeper soil, and have a higher cost. Determining which type of green roof to install depends on factors including budget and the structural capacity of the roof.

Intensive green roofs are typically meant for public use and are modeled after a garden you would find on the ground. They may contain a variety of plants and functional items such as tables, chairs, and pathways. These types of green roofs are most suitable for flat roofs.

Extensive green roofs are not meant for public use. These green roofs feature soils and plants able to withstand hot and dry rooftop conditions as well as enough filtration to handle brief deluges of rain from storm events. Extensive green roofs may be installed on many roof types, though they are most suitable on roofs that have a five to twenty degree slope.

The concept of green roofing has been long-known to residents in Iceland, Scandinavia, the United Kingdom, Newfoundland, and Nova Scotia. In these areas, sod was typically used as a roof covering to help insulate homes. The first modern green roof was installed in Germany in the 1970s. Today, many green roofs are being installed atop buildings in urban areas. One of the major benefits of green roofs is their ability to reduce the “urban heat island effect.” According to the U.S. Environmental Protection Agency (EPA), the annual average daytime temperatures in cities containing one million or more people can be 1.8 to 5.4 degrees Celsius higher than surrounding areas. The urban heat island effect is even more dramatic at night, when average evening temperatures can differ by 12 degrees Celsius compared to surrounding areas.

Due to this increased air temperature, urban heat islands contribute to pollution and increased energy consumption, especially during peak hours. Urban heat islands are also associated with an increase in heat-related illnesses and mortality rates. Green roofs combat these effects in a number of ways. The EPA lists five different benefits of green roofing. These benefits include:

• reduced energy use
• reduced air pollution and greenhouse gas emissions
• improved human health and comfort
• enhanced stormwater management and water quality
• improved quality of life

One of the major drawbacks of a green roof is its cost. Not surprisingly, installing a green roof is more expensive than just installing a traditional roof. In fact, green roofs tend to cost 30 to 60 percent more than traditional roofs. An extensive green roof typically costs $10 per square foot. Intensive green roofs typically cost $25 per square foot. Maintenance costs, such as watering and fertilizing the plants, is an additional cost to consider. Proponents of green roofs argue that though they are more expensive than traditional roofs at the outset, the green roofs are less expensive in the long run due to reduced energy requirements from the building itself, reduced costs for stormwater management, and a longer life of the roof in general.

This unusual green roof design covers the top of the California Academy of Sciences building in San Francisco. (Photo credit: Ambient Images Inc./Alamy)

Green roofs have been popping up on rooftops in a number of metropolitan areas throughout North America. One such city is Chicago, Illinois, which is home to more than 200 green roofs, which accounts for 2.5 million square feet of landscaped roofing. Even Chicago’s City Hall features a 20,000 square foot green roof made up of of 20,000 plants that encompass 158 different varieties. The 24.5-acre Millennium Park, built over Millennium Park Garage, is considered by many to be the world’s largest intensive green roof, regardless of its ground-level location.

Given the benefits of green roofing to urban areas, many cities are investing in this special type of urban landscaping. Several cities, including Chicago, Cincinnati, Ohio, and Portland, Oregon, offer grant programs to help fund green roof building projects. Much of this money originates from funding provided by the EPA.

More to Explore

• Green Roofs
• Green Roofs in Urban Landscapes
• Chicago Green Roofs
• Green Roofs for Health Cities

Green roofs are becoming a common sight in many cities. (Photo credit: Megapress / Alamy)

The komodo dragon is a reptile endemic to Indonesia. (Photo credit: Wolfgang Kaehler/Alamy)

The Komodo dragon is the world’s largest living lizard. Male lizards can grow up to ten feet in length and weigh around 200 pounds. Females tend to be slightly shorter (growing to a length of eight feet) and weigh around 150 pounds. These unusual lizards live in the lower dry forest and savanna habitats of four volcanic islands (Komodo, Gila Montang, Rinca, and Flores) within Indonesia’s Lesser Sundra Islands. The population of komodo dragons across these four islands is estimated to be between 3000 and 4000 individual animals. Komodo dragons are considered to be an endangered species due to factors including the loss of adequate habitat, poaching, and natural disasters.

Though some female Komodo dragons have been known to reproduce asexually, that is, they are able to fertilize their own eggs, most Komodo dragons reproduce by sexual means. The lizards mate between the months of May and August. Male lizards wrestle together to gain access to females. Following a victory, a male Komodo dragon mates with a female, fertilizing her eggs. In September, the female lizard lays a clutch of between 20 and 30 eggs into a nest. The female then incubates the eggs for a period of seven to nine months. Upon hatching, the young Komodo dragons have to fend for themselves, and many do not survive to adulthood.

In addition to their formidable size, komodo dragons also have a ferocious bite. A komodo dragon’s mouth is filled with 60 serrated, shark-like teeth that are able to tear chunks of flesh out of its prey when feeding. The teeth are embedded within its gums. When it begins to feed, the lizard’s gums begin to bleed, meaning feeding time can be a particularly gruesome sight. In addition, the Komodo dragon has a flexible skull, which lets it swallow large hunks of food at one time.

The komodo dragon's serrated teeth pop out of its gums when it is ready to feed. (Photo credit: Anna Yu/Getty Images)

Like crocodiles, komodo dragons are ambush predators. When ready for a meal, the lizards lie in wait, and spring upon their unsuspecting prey in a violent maelstrom of super-sharp teeth and claws. Even if a prey item is somehow able to survive the initial attack, it most likely will die soon after due to blood poisoning—a komodo dragon harbors over 50 different strains of bacteria in its mouth. Komodo dragons have a keen sense of smell and have been known to track the presence and direction of a kill as far as 2.5 miles away. These reptiles detect odors like a snake. A Komodo dragon uses its long, forked tongue to gather particles from the air. Next the lizard moves its tongue against its Jacobson’s organ, a sensory receptor located in the roof of its mouth, to identify airborne molecules.

A Komodo dragon is an indiscriminate eater—it eats nearly 90 percent of each kill it makes, including hooves, bones, and skin. It will also eat its prey's intestines, first swinging them about to remove any fecal matter before chowing down. Komodo dragons are voracious eaters. In fact, a Komodo dragon tends to eat up to 80 percent of its body weight at one feeding. When young, Komodo dragons typically eat smaller items such as insects, birds, eggs, and small mammals. As adults, Komodo dragons have been known to eat deer, smaller pigs, water buffalo, and smaller Komodo dragons. At times, humans have also become a Komodo dragon’s prey. Though uncommon, four people have been killed by Komodo dragons since 1974, and eight people have been injured by the lizards in the previous decade.

Recent research indicates that there may be more than just virulent bacteria that kills a Komodo dragon’s prey. In 2006, Dr. Brian Fry and a colleague published a scientific study that indicated that some lizards may share with snakes the same gene responsible for venom production. Following an unfortunate outbreak of a deadly virus in a population of Komodo dragons held at the Singapore Zoo, Fry and his colleagues were able to collect specimens to study. The scientists discovered that Komodo dragons have a set of glands that make venomlike proteins. These proteins can cause a rapid drop in blood pressure and/or prevent blood from clotting. In a paper published recently in the Proceedings of the National Academy of Science, Fry and his fellow researchers conclude that when a Komodo dragon bites into its prey, it adds venom to the wound, which causes the prey to bleed uncontrollably and/or lose consciousness due to a rapid drop in blood pressure.

Not all scientists are convinced by this research, however, and find any compelling evidence lacking. Further research is required to determine if Komodo dragons truly pack some venom in their already deadly bite.

More to Explore

• National Geographic: Komodo Dragon
• Komodo Dragon
• Komodo Dragon Fact Sheet
• For reasons unknown, Komodo dragons lashing out
• Female Komodo Dragon Has Virgin Births
• Chemicals in Dragon’s Glands Stir Venom Debate