Thousands of years after first becoming domesticated, the house cat remains a beloved family pet. (Photo: Dave Morris/Flickr via Creative Commons)

Most people view cats as harmless pets, but for birds and small mammals, the domesticated feline can be a deadly killer.

A new study in Nature Communications finds bird and mammal mortality caused by outdoor cats is much higher than has been previously reported. Annual bird deaths in the United States are now estimated to be 1.4 to 3.7 billion, while mammal mortality runs from 6.9 to 20.7 billion individual animals.

Stray cats, as opposed to those that are owned and cared for by humans, cause the majority of these deaths, according to researchers from the US Fish and Wildlife Service (FWS) and the Smithsonian Conservation Biology Institute, who conducted the study.

The study, by two of the world’s leading science and wildlife organizations, offers the one of the most comprehensive analyses on outdoor cat predation.

The ancient Egyptians may have been the first to domesticate the cat more than 4,000 years ago. The animal became a favored household pet over the centuries, in large part due to their natural ability to hunt and eradicate household pests and vermin, such as mice and rats.

But that natural hunting ability could be a key reason cats are listed as one of the 100 worst non-native invasive species in the world, according to the Global Invasive Species Database, which was published in 2000.

A cat with its catch, a bird called the American Coot (Photo: Debi Shearwater)

A separate 2011 study found free-ranging cats have caused or contributed to 14 percent of modern bird, mammal and reptile extinctions on islands. The same report also found that feral cats cause a substantial proportion of total wildlife mortality.

Dr. George Fenwick, president of American Bird Conservancy, a group which has called for action on this issue for many years, reacted to this latest report. “This study, which employed scientifically rigorous standards for data inclusion, demonstrates that the issue of cat predation on birds and mammals is an even bigger environmental and ecological threat than we thought. No estimates of any other anthropogenic [human-caused] mortality source approach the bird mortality this study calculated for cat predation.”

However, the Humane Society of the United States questioned the report’s numbers.  “The HSUS values both cats and wildlife. There is a legitimate issue with free-roaming cats preying on birds and other wildlife, and we are working to change that in a meaningful way,” said Wayne Pacelle, president and CEO of the Humane Society of the US. “Despite the scientific rigor with which this report was prepared, like others recently published, it tries to attach a number to something that is almost impossible to credibly quantify.”

The larger issue, according to the humane society,  is finding practical and humane actions to mitigate the impact of cats in communities.

Current policies for managing feral cat populations and regulating pet ownership usually focus more on animal welfare rather than ecological impacts, according to authors of the latest study.

The domesticated cat’s natural hunting abilities help homeowners keep their homes pest and vermin free. (Photo: Cobalt123/Flickr via Creative Commons)

One of the more popular forms of managing free-ranging cats includes Trap-Neuter-Vaccinate and Return colonies,  a method of humanely trapping feral cats, spaying or neutering them as needed, vaccinating the animals for diseases like rabies, and then releasing them back to the same location where they were collected.

The study asserts these methods of managing feral cats are employed throughout the US without widespread public knowledge, consideration of scientific evidence, or the environmental review processes typically required for actions with harmful environmental concerns.

The researchers recommend scientifically sound conservation and policy intervention to reduce the negative impact of feral cats on wildlife.

Waste heat from major cities is contributing to warmer winters, according to a new study. (Photo: Petr Magera via Creative Commons at Flickr)

Everyday energy consumption in urban areas could be significant enough to cause winter temperatures to rise.

According to a new study funded by the US National Oceanic and Atmospheric Administration (NOAA), waste heat released in major cities in the Northern Hemisphere in the northern-most parts of North America and Eurasia.

“The world’s most populated metropolitan areas, which also have the highest rates of energy consumption, are along the east and west coasts of the North American and Eurasian continents, underneath the most prominent atmospheric circulation troughs and ridges,” said Ming Cai, from Florida State University and an author of the study. “The concentrated and intensive release of waste energy in these areas causes a noticeable interruption to normal atmospheric circulation systems, leading to remote surface temperature changes far away from the regions where the waste heat is generated.”

According to the study published Nature Climate Change, the total amount of energy consumed throughout the world in 2006 was 16 terawatts, 16 trillion watts with 6.7 terawatts of that amount consumed within the 86 metropolitan areas considered in the study.

“The burning of fossil fuel not only emits greenhouse gases but also directly effects temperatures because of heat that escapes from sources like buildings and cars,” said Aixue Hu of the National Center for Atmospheric Research in Boulder, Colorado, another of the study’s authors.

The excess energy and resulting warmer winter temperatures could also help explain the discrepancies between actual observed warming over the last half-century, compared to the amount of warming that computer models have been able to account for.

US National Weather Service illustration of two atmospheric systems known as jet streams traveling northeast across the United States. (NOAA)

Waste heat from urban areas is different from energy found naturally in atmosphere, such as what’s produced by our Sun-warmed planet.  That atmospheric energy is normally distributed from one region to another by various circulation systems, like the Jet Stream.

Humans consume energy produced by fossil fuel sources, oil and coal, that have stayed hidden and unused for millions of years.  Although the amount of energy produced and used by humans represents only a small portion of what’s actually transported throughout the atmosphere by nature, the researchers say that it is highly concentrated in urban areas.

“What we found is that energy use from multiple urban areas collectively can warm the atmosphere remotely, thousands of miles away from the energy consumption regions,” said study co-author Guang Zhang, from Scripps Institution of Oceanography. “This is accomplished through atmospheric circulation change.”

The influence of heat generated in urban areas can widen the jet stream and strengthen atmospheric flows in regions located at mid-latitudes, areas which lie between the tropics and the polar regions of the world.

Researchers point out this warming effect generated by urban heat is not necessarily even and uniform throughout the world.  They say changes in major atmospheric systems, that can cool parts of Europe by up to 1 degree C mostly during the fall, can offset this heating effect. That’s why the impact of the urban winter heat on global temperatures is slight, raising the temperature by an average of about .1 degree C worldwide.

The study does not address whether the effects of urban heating can actually disrupt atmospheric weather patterns or if it plays any role in hastening global warming.

Artist drawing of Landsat-5 in space (Image: USGS)

The longest operating Earth-observing satellite is about to be decommissioned by the US Geological Survey.

The USGS has begun the task of lowering Landsat-5 from its operational orbit.  The first series of maneuvers in that effort is likely to take place within the next month.

Landsat-5 was the fifth of seven satellites launched as part of the Landsat program, which has been acquiring satellite imagery of Earth since 1972.

Launched from California on March 1, 1984, Landsat-5 has circled Earth more than 150,000 times.

According to the USGS, which helps manage the mission, the satellite has been an extraordinary success, providing valuable contributions to the global record of land change.

Its original mission was only supposed to last three years, but Landsat-5 continued to deliver imagery and data for more than 25 more years beyond that.

The satellite experienced a number of problems over the years, but scientists and technicians managed to bring it back from the brink of failure.

This image of the abandoned city of Pripyat, home to the Chernobyl Nuclear Power Plant was taken by Landsat-5 three days after the April 26, 1986, nuclear accident. (NASA)

However, the recent failure of one of its gyroscopes proved to be one problem too many, finally bringing Landsat-5′s decades-long mission to an end.

“This is the end of an era for a remarkable satellite, and the fact that it flew for almost three decades is a testament to the NASA engineers and the USGS team who launched it and kept it flying well beyond its expected lifetime,” said Anne Castle, Department of the Interior assistant secretary for Water and Science. “The Landsat program is the gold standard of satellite observation, providing an invaluable public record of our planet that helps us tackle critical land, water, and environmental issues.”

Over more than a quarter of a century, Landsat-5  observed and sent back Earth imagery and data  reflecting the many changes which have taken place on our planet, not only from natural hazards and a changing climate, but also due to land use practices.

It observed the eruption of Mount Saint Helens, the 1991 Kuwaiti oil fires set by a fleeing Iraqi military, the 1986 Chernobyl nuclear disaster, as well as rainforest depletion, wildfires, floods, global crop production, and the expansion and retreat of the Earth’s ice shelves.

Image taken by Landsat-5 in 1991 shows inky-black smoke pouring from burning oil wells which were set afire by defeated Iraqi military forces as they retreated from Kuwait. (NASA)

“Any major event since 1984 that left a mark on this Earth larger than a football field was likely recorded by Landsat-5, whether it was a hurricane, a tsunami, a wildfire, deforestation, or an oil spill,” said USGS Director Marcia McNutt. “We look forward to a long and productive continuation of the Landsat program, but it is unlikely there will ever be another satellite that matches the outstanding longevity of Landsat-5.”

Landsat-5 observations have helped increase our understanding and awareness of the impact humans have on the land, according to the USGS.

With Landsat-5 out of commission, a number of Earth-observing satellites put into space by other governments and private companies, continue to operate.

Landsat-7, which launched in 1999, and the upcoming  Landsat-8 (LDCM), which launches in 2013, will take up where Landsat-5 left off, continuing to keep watch over an ever-changing planet.

This NASA image shows the work site of the Curiosity rover on Mars. The first test of Martian soil by Curiosity shows no definitive evidence that the red planet has the chemical ingredients to support life. (NASA)

NASA’s artist rendering of Voyager 1 at the edge of the solar system. The long-running spacecraft has entered the fringes of the solar system which is thought to be the last layer before the beginning of interstellar space, or the space between stars. Mission chief scientist Ed Stone says Voyager 1 will be the first manmade object to leave the solar system. (AP Photo/NASA)

A 68-mile-diameter crater, large indentation at center, in the north polar region of Mercury which has been shown to harbor water ice, thanks to measurements by the Messenger spacecraft. (AP Photo/NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

Joe Wasilewski works with a captured Nile crocodile, caught near his Homestead, Fla., home. State wildlife officials have given their agents a rare order to shoot to kill in the hunt for a young and potentially dangerous Nile crocodile loose near Miami. “They get big. They’re vicious. The animals are just more aggressive and they learn that humans are easy targets,” says Wasilewski, a reptile expert and veteran wrangler. (AP)

The Plosky Tolbachnik volcano erupts in Russia’’s Far Eastern Kamchatka Peninsula. The volcano, located on the peninsula’s eastern coast, is erupting for the first time in 36 years. (AP)

In an undated photo, Glenn Storrs, left, helps haul a dinosaur fossil on a contraption made from two hospital gurneys and a motorcycle wheel, dubbed the dino wheel, near Pryor Mountains in Montana. After 10 years of painstakingly unearthing scattered dinosaur fossils at a site along the base of the Pryor Mountains, Storrs believes he has finally figured out how the bones arrived at their final resting place 145 million to 150 million years ago. His theory is that a group of young dinosaurs, probably migrating with adults, died of thirst while searching for a wetter environment.
   (AP Photo/Courtesy of Cincinnati Museum Center via The Billings Gazette)

A shadow self-portrait taken by NASA’’s Opportunity rover on the Martian surface. The solar-powered spacecraft has been exploring a huge crater in the Martian southern hemisphere and has detected what appear to be clay minerals. (AP Photo NASA)

Multiple dust plumes are seen blowing off the coasts of Iran and Pakistan in this NASA handout image taken Nov. 29, 2012. These images document the movement of the plumes southward over the Arabian Sea. (REUTER/NASA/Jeff Schmaltz)

The moon Tethys (in the upper left of the image) is seen next to Saturn in this NASA image taken from the Cassini spacecraft on Aug. 19, 2012 and released Dec. 3, 2012. Saturn’s rings appear to dwarf Tethys (660 miles, or 1,062 kilometers across) although scientists believe the moon to be many times more massive than the entire ring system combined. The view was acquired at a distance of approximately 1.5 million miles (2.4 million kilometers) from Saturn. (REUTERS/NASA)

n this photo made Thursday, Nov. 29, 2012, The Plosky Tolbachnik volcano erupts in Russia on Thursday, Nov. 29, 2012, for the first time in 36 years. (AP)

Scanning electron micrograph of very small and numerous bacterial cells inhabiting icy brine waters in Antarctica’s Lake Vida. (Photo: Christian H. Fritsen, Desert Research Institute)

Scientists say they have found ancient microbial life in dark and very salty water some 20 meters below the surface of a frozen and isolated Antarctic lake. The finding could provide scientists with insight into how life could possibly exist in the most extreme environments on Earth as well as elsewhere throughout the cosmos.

In a study recently published in the Proceedings of the National Academy of Science (PNAS) the researchers say they took the microbes from the Antarctic’s Lake Vida, which contains no oxygen but has the highest nitrous oxide levels found in any natural bodies of water on Earth. The scientists describe the icy environment in which the sample microbes were taken as a briny liquid, about six times saltier than normal seawater and with an average temperature of minus 13.5 degrees centigrade.

“This study provides a window into one of the most unique ecosystems on Earth,” said lead author Dr. Alison Murray from the Desert Research Institute (DRI) in Reno, Nevada. “Our knowledge of geochemical and microbial processes in lightless icy environments, especially at subzero temperatures, has been mostly unknown up until now. This work expands our understanding of the types of life that can survive in these isolated, cryoecosystems (ecosystems found in ice) and how different strategies may be used to exist in such challenging environments.”

Previous studies going back to 1996 show the Lake Vida brine and its microbial residents have had to do without outside resources that normally support life (i.e.: sunlight or oxygen) for more than 3,000 years. Despite what many would consider being an unlivable habitat, the researchers in this project found that the polar lake supports what they call a surprisingly diverse and large community of bacteria that can survive the harsh conditions.

To ensure that their samples and the microbe’s ecosystem weren’t affected or contaminated by human or other external influences, the researchers developed specialized equipment and a set of very strict procedures when they set out to retrieve them during expeditions to the Antarctic back in 2005 and 2010.

Members of the 2010 Lake Vida expedition team use a sidewinder drill inside a secure, sterile tent on the lake’s surface to collect samples for their research. (Photo: Desert Research Institute, Emanuele Kuhn)

Regarding the high levels of nitrous oxide that was found in the lakes salty water, the scientists say that geochemical analyses are suggesting that the N₂O was generated by chemical reactions between the salty water and the lake’s iron-rich sediments. The chemical reaction also produced an amount of molecular hydrogen, which the researchers say may be what has been providing the energy that was needed to sustain the community of diverse microbial life.

“It’s plausible that a life-supporting energy source exists solely from the chemical reaction between anoxic salt water and the rock,” explained co-author Dr. Christian Fritsen, also from DRI.

“If that’s the case,” Murray said, “this gives us an entirely new framework for thinking of how life can be supported in cryoecosystems on earth and in other icy worlds of the universe.”

Murray said that the scientists involved with the project are continuing their research by analyzing the non-organic components, the chemical interactions between Lake Vida brine and sediment, and by using various methods of genome sequencing, and are learning more about their rare microbial find.

They also suggested the research and findings produced for this study could also provide some help to others who conduct investigations into possible cryoecosystems that might be found in the soil, sediments, wetlands, and other lakes that lie beneath the Antarctic ice sheet.

A juvenile Gobidon (goby) fish is shown on an Acropora coral. These fish spend their entire lives with the same coral, protecting it from encroaching seaweed. (Photo: Georgia Tech/Joao Paulo Krajewski)

Coral reefs provide one of the world’s most vital ecosystems and some of these reefs are in danger of being destroyed.

While people are to blame for much of the destruction, nature also plays a role. Encroaching species of seaweed with poisonous compounds on their surfaces are one of nature’s threats.

The toxic seaweed begins its lethal damage upon contact with the coral, killing its tissue within two to three days of contact.

But now scientists at the Georgia Institute of Technology have found that one species of coral near the Fiji Islands  doesn’t sit around waiting to  destroyed; it actually sends out a call for help when it’s threatened by poisonous seaweed.

Small fish, known as gobies, which are about two centimeters long and spend their entire lives in the crevices of the coral, respond to the coral’s alarm within minutes.

The gobies go after the seaweed, chewing and mowing it away from the coral. Not only do the little fish protect their homes, but some species also use the toxic substances from the seaweed to build up their own protective arsenal.

Mark Hay, a biology professor at Georgia Tech and colleague Danielle Dixson conducted the research and published their findings in Science.

Hay said two species of goby serve as coral bodyguards.  One species simply chews away at the harmful seaweed and then spits it out, but the other type of fish actually ingests the poisonous substance. This enhances the fish’s already toxic characteristics, increasing its ability to protect itself from predators.

Coral protector Gobidon histrio (goby) in its living space on the coral Acropora nasuta. The coral is in contact with the toxic green alga Chlorodesmis fastigiata. (Photo: Georgia Tech/Danielle Dixson)

Researchers were unable to determine whether the fish were saving up the lethal seaweed compounds to use on enemies, or if they were already making their own poisons, and using the noxious material to build up their resistance to the poisons.

Not all fish possess the gobies’ protective instincts. Scientists also studied two other species of small fish that live in the coral.

According to Hay, these damsel fish simply swim away, moving on to other coral, when their homes are threatened.

“They just abandon it, say ‘It’s going to die, we’re out of here,’” Hay says.

Interestingly enough, the gobies are only protective when their particular species of coral is under attack.  The scientists placed the gobies within another closely-related species of coral and found that the little bodyguards did not respond or protect their new home when it was under a similar threat.

Hay hopes to study other species of coral in the future to see if they too are also aided by rapid responding protective fish.

Mark Hay joins us this weekend on the radio edition of Science World.  Tune in (see right column for scheduled times) or check out the interview below.

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A western honeybee (Photo: Wolfgang Hägele via Wikimedia Commons)

A new study finds prolonged antibiotic use by beekeepers might play a role in the mysterious drop in honey bee populations in the United States.

Yale researchers found genetic evidence that helpful bacteria, which normally live the bellies of honeybees, have become highly resistant to the antibiotic tetracycline, possibly weakening the bees’ ability to fight disease.

Researchers say decades of use may have unknowingly encouraged antibiotic resistance by genetically altering the beneficial bacteria.

Past studies show helpful bacterial play an important role in protecting the honeybee by neutralizing toxins found in their diets while also helping fight off various pathogens.

The  researchers have identified eight different tetracycline resistance genes among U.S. honeybees that were exposed to antibiotics.  Those same resistance genes were missing in bees from countries where antibiotic use is banned.

“It seems to be everywhere in the U.S.,” says Nancy Moran of Yale University, a senior author on the study. “There’s a pattern here, where the U.S. has these genes and the others don’t.”

In the 1950s, beekeepers started using the antibiotic oxytetracycline, a compound similar to tetracycline, which is commonly used in humans. They were trying to fight a devastating bacterial disease called foulbrood, which can wipe out a hive more quickly than beekeepers can react to the infection.

But after years of use  the microorganisms eventually acquired a resistance to tetracycline, possibly weakening the honeybee’s resistance to other diseases.

“It seems likely this reflects a history of using oxytetracycline since the 1950s,” says Moran. “It’s not terribly surprising. It parallels findings in other domestic animals, like chickens and pigs.”

A beekeeper tends to a beehive. (Photo: Emma Jane Hogbin via Creative Commons at Flickr)

The researchers took bee samples from the Czech Republic, New Zealand and Switzerland, which do not allow their beekeepers to use the antibiotics.

Researchers found  those bees had only two or three different resistance genes and even then only in very low numbers, suggesting that prolonged antibiotic use in the US bees may have played a role in developing the resistance genes.

Moran  points out that the antibiotic-resistant genes researchers found in the bellies of the honeybee do not pose a direct risk to humans.

Those microorganisms, according to Moran, “don’t actually live in the honey, they live in the bee. We’ve never actually detected them in the honey. When people are eating honey, they’re not eating these bacteria.”

Nancy Moran joins us this weekend on the radio edition of Science World.  She tells us more about how treatment meant to strengthen honeybee hives in the U.S. may have actually weakened them instead. Tune in (see right column for scheduled times) or check out the interview below.

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This graphic shows the extent of Arctic sea ice on Aug. 26, 2012, the day the sea ice dipped to its smallest extent in more than three decades of satellite measurements, according to scientists from NASA and the National Snow and Ice Data Center. (Image: NASA)

The Arctic sea ice cover has melted to its lowest extent since satellite observations of it began more than three decades ago, breaking a previous record low set in 2007.

NASA and scientists at the University of Colorado, Boulder report the Arctic sea ice extent  -  the amount of ice covering the sea surface – fell to 4.10 million square kilometers in Aug. 26, 2012.  And, with more days left in the summer melting cycle, they anticipate even more of a loss before the freeze cycle begins at the end of September.

“By itself it’s just a number, and occasionally records are going to get set. But in the context of what’s happened in the last several years and throughout the satellite record, it’s an indication that the Arctic sea ice cover is fundamentally changing,” said Walt Meier, a scientist at the National Snow and Ice Data Center (NSIDC) at the University of Colorado.

Sea ice in the Arctic goes through a regular yearly cycle of growing and melting. While it doesn’t raise sea level, says Meier, it does have an effect on the climate systems through how much energy gets absorbed from the sun.

Since the Arctic sea ice observational record began in 1979,  the trend of ice melt went from slow and steady to more significant as time went on.

Over the last 10 years, according to Meier, this trend quickly began to escalate, with record-breaking years of sea ice melt along the way. The significant drop in the amount of Arctic sea ice, says Meier, “is a kind of an exclamation point on the long term trend.”

Scattered ice floes seen from the bridge of the USCGC Healy on August 20, 2012 northwest of Barrow, Alaska. Arctic sea ice fell to its lowest daily extent in the satellite record on Sunday, August 26, 2012. (Photo: U.S. Coast Guard)

NSIDC officials say the previous record low, set back in 2007, happened because of a near-perfect summer weather for melting ice.

“The Arctic used to be dominated by multiyear ice, or ice that stayed around for several years,” Meier said. “Now it’s becoming more of a seasonal ice cover and large areas are now prone to melting out in summer.”

Because of this, he said, what’s occurring now is an overall thinning of the multiyear ice cover, as well as a decrease in the seasonal ice cover.

That thinning continues throughout the entire year because the ice in the wintertime is also thinner than it used to be, reflecting what Meier calls “another big change in the Arctic sea ice system.”

Meier worries about changes to the Arctic, and consequently Earth’s weather systems, should this trend of escalated sea ice melt continue.

The sea ice is very reflective, it’s white and reflects most of the sun’s energy, says Meier. Because there is continuous daylight during the Arctic summer, most of that solar energy is reflected back into space; it doesn’t warm things and helps keep the Arctic cool. Meier calls this process not only the Arctic’s “air conditioner,” but also the entire Earth’s “air conditioner” as well.

“As we lose that sea ice in the summertime,” says Meier, “it gets replaced by the ocean which is very dark relative to the sunlight. It absorbs most of that energy, reflects very little of it, and that energy then heats up the ocean, which heats up the atmosphere and makes the entire Arctic warmer than it normally would be without sea ice.”

Animals which have long resided in the Arctic, such as the polar bear, could be in danger if the current trend of Arctic sea ice melt continues (Photo: Yukon White Light on Flickr/Creative Commons)

This causes greater warming, taking what has been the globe’s air conditioner and kind of “draining out the coolant,” says Meier.  As a result, the ability and efficiency of that process to help cool the Earth is reduced as more and more sea ice is lost in the summertime.

There has been a sort of climate balance on Earth between cold in the polar areas and warmth in the equatorial regions. The contrast between the polar cold and the equatorial warmth, according to Meier, sets up weather patterns like the jet-stream, ocean currents, storm tracks and where, when and how much it rains.

Changes in either climate system  throw off this balance and disrupt weather patterns. There’s not enough data right now to say for sure what the exact impacts these weather changes will bring, but Meier  suspects areas that are dependent on predictable weather patterns – such as agriculture and other things needed to help sustain life on Earth – may be affected.  It’s possible, he says, that droughts may become harsher or that more flooding will occur.

Accelerated melting could also impact animals,  such as polar bears, who make their homes on the Arctic ice. Meier says some of these polar animals will find new habitats to live in, but others will be forced to either adapt to the changing climate conditions or face extinction.

Walt Meier joins us this weekend on the radio edition of Science World.  Check out the right column for scheduled air-times or listen now to the interview below.

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