February 13, 2013
Indonesia’s numerous islands (18,307 to be exact) house a wealth of avian biodiversity, yet scientists speculate that many of the country’s bird species have yet to be discovered or categorized. But ornithologists are celebrating today as a new species of owl joins the list, taking filling in one more spot in the catalog of the archipelago’s animals.
In 2003, George Sangster, a Dutch ornithologist from Stockholm University, and his wife were exploring the forested foothills of Lombak, an island just east of Bali. While traipsing through the forest at night, Sangster picked up on an owl call he did not recognize. Coincidentally, just a few days later Ben King, an ornithologist from the American Museum of Natural History, heard those same calls from the jungle and also suspected they came from an unknown species.
“It was quite a coincidence that two of us identified this new bird species on different parts of the same island, within a few days of being on the island, especially considering that no-one had noticed anything special about these owls in the previous 100 years,” Sangster said in a statement.
Locals on Lombak, it turned out, were familiar with the species. Known as burung pok–roughly translated as “pook,” a mimic of the owl’s hoots–the birds turned out to be a common feature of the nocturnal landscape. But locals on neighboring islands, however, said they had never heard of the bird and did not recognize its unusual call.
Here, you can hear the little Indonesian owl hooting into the night, which the researchers describe as “a single whistle without overtones:
Although birders and scientists alike love owls, surprisingly not much is known about those species’ biology, including how they relate to one another on an evolutionary scale. Lately, however, researchers have been working double time to get a grip on owls. In 1975, for example, scientists knew of 146 species, and that number leapt to 250 as of 2008. One driver behind this jump in species numbers was the realization that owl calls could lend clues (PDF) to classifying different types of owls. Owls hoot to attract mates and recognize one another as the same, so animals evolved calls unique to their species. In some cases, owls previously classified as the same species were split in two primarily on the basis of their calls.
Sangster, King and two other researchers from Sweden and Australia got together and were able to photograph the owls by playing back recordings of the call to attract several of the hooting culprits. Digging through old records, the researchers found that the owls matched specimens collected back in 1896 by Alfred Everett, a British administrator who was based in Borneo and spent his spare time collecting natural history curios. That same year, Ernest Hartlet, a naturalist who reported on Everett’s field work, accurately noted that “the cry is a clear but not very loud ‘pwok,’ like that of [O.] lempiji, but somewhat different in tone.”
Though Hartlet and Everett came close to identifying the new species, they fell just short of making the leap. Since then, no one had collected or observed this type of owl, according to records from the American Museum of Natural History and the Natural History Museum at Tring, in the U.K.
All of this evidence, the team concluded in a PLoS ONE paper, pointed to the discovery of a new species of owl.
Because the new owl shows dramatically less individual variation to its brown and cream-speckled feather patterns than similar species found on neighboring islands, the scientists hypothesize that ancestors of the Lombok owls may have been isolated and trapped on their island many years before by a catastrophic volcanic eruption. Starting with just a handful of individuals, the animals then could have slowly rebuilt their populations, eventually evolving into a unique lineage.
The species, they report, is the first bird known to be unique to Lombok. The authors named the new bird Otus jolandae, after Sangster’s wife, Jolanda.
We often hear stories of animal love—tales of rare monogamy in the animal kingdom where life-long love is implied. But there is a distinction between romantic love and an efficient mating system. Here’s a look at some ocean animals to see what is really going on.
Albatrosses Get ‘Romantic’ to Increase Chick Survival
Albatross relationships seem especially relatable to humans. These long-lived and highly-endangered birds will court each other through ritual dances for years. Albatrosses are slow to reach sexual maturity, and some species even delay breeding for several years to learn specific mating rituals and to pick the perfect partner. The courtship behavior slows down once the pair bonds (an all too familiar aspect of human relationships). Once a pair is comfortable and breeding commences, they will return to each other and the same spot each year; for most albatross species, the bond lasts their entire life.
So is it love? The biological reality is that albatrosses only lay a single egg a year. With both parents fully invested in chick survival, their genetic heritage is most likely to survive. It may seem like love, but with those low reproduction rates no parents can afford to be deadbeats.
Seahorses Bond to Improve the Odds of Birth
If albatross relationships are reminiscent of fairytale romance, seahorses might be considered the swingers of the sea. Many seahorse species will bond with a mate, but that bond often lasts only through a single breeding season or until a more attractive female comes along. But, monogamy in this case is useful since it can be hard to find fellow seahorses due to poor swimming skills and low densities.
There is evidence that the longer that partners are together, the more successful at breeding they become and the two are able to produce more offspring per brood. One species of seahorse does appear to stick with a single mate for life: the Australian Hippocampus whitei. Practice makes perfect!
Two Angelfish Make a Strong Defense
Typically in pairs, French angelfish (Pomacanthus paru) help each other defend their territory against other fish. The couples have been observed spending extended periods of time together, exhibiting more of a monogamous social structure. Genetic monogamy (i.e. testing fertilized eggs to confirm they come from a single father) hasn’t been confirmed, but there have been observations of pairs traveling to the water’s surface to release their eggs and sperm together.
Monogamy is not that common in fishes, and it is mostly found in tropical and subtropical waters. Care needed from two parents, joint defense of territories, and difficulties in finding a mate all can play a role.
A Permanent Glass Home for Shrimp
These intriguing glass sponges, called Venus’s flower-baskets (Eupectella aspergillum), are made of flexible silica that can better transmit light than our man-made fiber-optic cables. And many of these beautiful deep-sea sponges are also home to a monogamous pair of shrimp.
Several species of shrimp find refuge in these sponges, but due to the limited space found within the fine-mesh silica, only two adult shrimp can fit inside—and they are stuck there for life. The two spend their days cleaning the sponge and eating whatever bits of food manage to flow through. After they breed, their small offspring can squeeze through the holes in the mesh to escape, but eventually they will settle into a new home with their own imprisoned mate.
The gift of this sponge, taken from the deep with the two dead shrimp still trapped inside, is considered good luck for couples marrying in Japan. It seems as though young human couples are not the only ones to share tight living spaces.
Learn more about the ocean from the Smithsonian’s Ocean Portal.
February 8, 2013
In the coming years, the birds of Asia’s Eastern Himalaya and Lower Mekong Basin, considered biodiversity hotspots by scientists, will need to relocate within the region to find viable habitat, according to a new study published in the journal Global Change Biology. The reason? Climate change. Researchers at England’s Durham University tested 500 different climate-change scenarios for each of 370 Asian bird species and found that every possible climatic outcome–even the least extreme–would have an adverse effect on the birds.
The researchers honed in on sensitive habitat in Bhutan, Laos, Cambodia, Vietnam and parts of Nepal and India, where development and population growth are occurring at a rapid clip and the effects of climate shifts are expected to be significant, with both wet and dry seasons intensifying. Portions of the region will suffer drastically, the study authors wrote, and certain climates will have “no present-day analogues” by 2100.
This will send birds in search of food. “Food availability [could become] more seasonal, meaning that in some periods there is an over-abundance of food, in others the birds starve,” lead author Robert Bagchi, formerly of Durham University and now a senior scientist at ETH Zürich, told Surprising Science. Species in the Lower Mekong Basin, which includes Laos, Cambodia and Vietnam, will be most vulnerable to these shifts.
In the most extreme cases, the research showed, birds will need to be physically relocated–an outcome scientists are hoping to avoid. Instead, they’re recommending proactive conservation. “Maintaining forest patches and corridors through agricultural landscapes is likely to be a far more effective and affordable long term solution than translocation,” Bagchi said. Linking bird habitat will be key so that species can move between sites that are currently viable and those that will suit them in the future.
The ramifications of bird relocation on plants and other animals has yet to be examined, but the shifts likely won’t bode well. Plant species that rely on birds to disperse seeds may not be able to survive, according to Bagchi. “Understanding how species interactions are going to change is very much at the cutting edge of what ecologists are trying to understand at the moment,” he said.
The study joins a growing body of research into how changes in climate affect food and water supplies, ranges, breeding habits and life cycles for birds and a variety of wildlife. Among those studied and deemed at risk are California’s threatened and endangered bird species. Research published last year showed that sea-level rise and changes in precipitation will most seriously imperil wetlands birds.
Investigators with the National Science Foundation are currently studying the prospects of Antarctica’s Adélie penguins for surviving climate change; the birds rely on floating sea ice, and if warmer temperatures melt that ice, the penguins will vanish. The top swimmers and foragers among their ranks have the best chances of survival, according to researchers, whose work is detailed in this video.
Among mammals, the adverse impacts of global warming on polar bear habitat has been well documented. A 2011 study showed the bears must swim longer distances in search of stable sea ice and that cubs are 27 percent more likely to die as a result of the extended plunges. New research published in the journal Ecology reveals that elephants are also vulnerable: Higher temperatures and lower precipitation have created an acute threat to Myanmar’s endangered Asian elephants, particularly babies.
Land-dwelling North American animals have also been affected. The snowmelt required by wolverines for reproduction is so greatly diminished that federal wildlife officials nominated the animal for Endangered Species Act listing earlier this month. And climate-change-induced, late-spring snowfalls have caused the Columbian ground squirrel to extend its Rocky Mountains hibernation by ten days over the past 20 years, according to Canadian researchers. By emerging later, the animals lose valuable time to stock up on the food they need to survive the next winter.
Conversely, another hibernator, the yellow-bellied marmot, was shown in a 2010 study to actually thrive in the face of climate alterations–a phenomenon scientists attributed to earlier-spring plant growth. But they predicted the benefits would be short-lived due to an increasingly serious climatic pitfall: drought.
Meanwhile, as temperatures continue to rise, other wildlife and insects are expected to flourish outright, including certain invasive species that will be able to expand their ranges and survive winters in new places, as well as non-invasive species. A recent Discovery news article highlighting climate-change winners focused on the brown argus butterfly, which has found a new host plant and a larger range; the albatross, whose food-finding ability has gotten a boost from shifting wind patterns; and the Australian gray nurse shark, whose population could boom if warmer waters reunite two separate populations. Also, melting Arctic ice could provide new feeding opportunities for orcas–but if so, two species it preys on, belugas and narwhals, would move into the climate-change losers column.
February 1, 2013
Ever wonder how owls can turn their heads almost all the way around?
They have a complex, adaptive network of protective blood vessels that make the structures in our necks look puny–a network that researchers have now dissected, mapped and illustrated for the first time.
“Until now, brain imaging specialists like me who deal with human injuries caused by trauma to arteries in the head and neck have always been puzzled as to why rapid, twisting head movements did not leave thousands of owls lying dead on the forest floor from stroke,” said Dr. Philippe Gailloud, an interventional neuroradiologist at Johns Hopkins and a senior researcher on the study, in a statement. A poster depicting these findings won first place in the 2012 International Science and Engineering Visualization Challenge, the journal Science announced yesterday.
The carotid and vertebral arteries in the neck of most animals, including owls and humans, are delicate and fragile structures. They’re highly susceptible to minor tears and stretches of vessel linings. In humans, such injuries can be common: whiplash sustained in a car accident, a back-and-forth jarring roller coaster ride or even a chiropractic maneuver gone wrong. But they’re also dangerous. Blood vessel tears caused by sudden twisting motions produce clots that can break off, sometimes causing an embolism or stroke that could prove fatal.
Owls, on the other hand, can rotate their necks up to 270 degrees in either direction without damaging the vessels running below their heads, and they can do it without cutting off blood supply to their brains.
Using medical illustations, CT scans and angiography, which produces X-ray images of the inside of blood vessels, researchers studied the bone structure and vascular structure in the heads and necks of a dozen snowy, barred and great horned owls after their deaths from natural causes. All three species are native to the Americas, their habitats stretching from Tierra del Fuego, the southernmost tip of the South American mainland, to the Arctic tundra of Alaska and Canada.
When researchers injected dye into the owls’ arteries to mimic blood flow and then manually turned the birds’ heads, they saw mechanisms at play that contrasted greatly with humans’ head-turning ability. Blood vessels at the base of the owls’ heads, just below the jawbone, kept expanding as more of the dye flowed in. Eventually, the fluid pooled into tiny reservoirs. Our arteries tend to get smaller during head rotations and don’t balloon in the same way.
Researchers believe this feature is crucial to support the top-heavy winged creatures. While they twist theirs heads back and forth, the owls’ reservoirs allow the birds to pool blood to sustain the function of their eyes and brain, which are both relatively large compared to the size of their heads. This interconnected vascular network helps minimize interruption of blood flow.
But these silent hunters’ head-on-a-swivel ability continued to be more complex, researchers found. In owls’ necks, one of the major arteries feeding the brain passes through bony holes in the birds’ vertebrae. These hollow cavities, known as the transverse foraminae, were ten times bigger in diameter than the artery passing through it. The researchers say the roomy extra space creates multiple air pockets that cushion the artery and allow it to travel safely during twisting motions.
“In humans, the vertebral artery really hugs the hollow cavities in the neck. But this is not the case in owls, whose structures are specially adapted to allow for greater arterial flexibility and movement,” said lead researcher Fabian de Kok-Mercado in the statement. De Kok-Mercado is a medical illustrator at Howard Hughes Medical Institute in Maryland.
This adaptation appeared in 12 of the 14 vertebrae in the owls’ necks. The vertebral arteries entered their necks higher up than in other birds, introduced at the 12th vertebrae (when counted from the top) instead of the 14th, which gives the vessels more slack and room to breathe. Small vessel connections between the carotid and vertebral arteries, called anastomoses, let blood flow uninterrupted to the brain, even when owls’ necks were contorted into the most extreme twists and turns.
“Our in-depth study of owl anatomy resolves one of the many interesting neurovascular medical mysteries of how owls have adapted to handle extreme head rotations,” de Kok-Mercado said.
Up next for the team is studying hawk anatomy to find out if other bird species possess owls’ adaptive features for looking far left and right.
January 29, 2013
There are so many ways for a little bird or squirrel to die these days–they can be squished by cars, splattered into buildings, run over by bulldozers, poisoned or even shot. But if you have ever had to clean up a mangled “present” left on your doorstep by a kitty, you’ll know that little creatures can also be killed by pets.
Cats in particular have earned a nasty reputation for themselves as blood thirsty killers of wildlife. They have been named among the top 100 worst invasive species (PDF) in the world. Cats have also earned credit for countless island extinctions. Arriving onto the virgin specks of land alongside sailors, the naive native fauna didn’t stand a chance against these clever, efficient killers. All said, cats claim 14 percent of modern bird, amphibian and mammal island extinctions. But what about the mainland?
A recent study aimed to find out just that. Now the stats are in, and it’s much worse than we thought. But before bird lovers rush to declaw pets, the study’s scientists also found that feral cats and strays–not house cats–are responsible for the majority of the killings.
To arrive at the new findings, researchers from the Smithsonian’s Migratory Bird Center and the U.S. Fish and Wildlife Center assembled a systematic review of every U.S.-based cat predation study known in the scientific literature (excluding Hawaii and Alaska). Based on figures the authors verified as scientifically rigorous, they statistically quantified the total bird and small mammal mortality estimate caused by cats, further breaking the categories down into domestic versus unowned cats, that latter of which the authors define as barnyard kitties, strays that receive food from kind humans and cats that are completely wild.
Their results paint a grim picture for wildlife. In a paper published today in Nature Communications, they write that between 1.4 to 3.7 billion birds lose their lives to cats each year in the United States. Around 33 percent of the birds killed are non-native species (read: unwelcome). Even more startlingly, between 6.9 to 20.7 billion small mammals succumb to the predators. In urban areas, most of the mammals were pesky rats and mice, though rabbit, squirrel, shrew and vole carcasses turned up in rural and suburban locations. Just under 70 percent of those deaths, the authors calculate, occur at the paws of unowned cats, a number about three times the amount domesticated kitties slay.
Cats may also be impacting reptile and amphibian populations, although calculating those figures remains difficult due to a lack of studies. Based upon data taken from Europe, Australia and New Zealand and extrapolated to fit the United States, the authors think that between 258 to 822 million reptiles and 95 to 299 million amphibians may die by cat each year nationwide, although additional research would be needed to verify those extrapolations.
These estimates, especially for birds, far exceed any previous figures for cat killings, they write, and also exceed all other direct sources of anthropogenic bird deaths, such as cars, buildings and communication towers.
The authors conclude:
The magnitude of wildlife mortality caused by cats that we report here far exceeds all prior estimates. Available evidence suggests that mortality from cat predation is likely to be substantial in all parts of the world where free-ranging cats occur.
Our estimates should alert policy makers and the general public about the large magnitude of wildlife mortality caused by free-ranging cats.
Although our results suggest that owned cats have relatively less impact than un-owned cats, owned cats still cause substantial wildlife mortality; simple solutions to reduce mortality caused by pets, such as limiting or preventing outdoor access, should be pursued.
The authors write that trap-neuter/spay-return programs–or those in which feral cats are caught, “fixed,” and released back into the wild unharmed–are undertaken throughout North American and are carried out largely without consideration towards to native animals and without widespread public knowledge. While cat lovers claim that these methods reduce wildlife mortality by humanely limiting the growth of feral colonies, the authors point out that the scientific literature does not support this assumption. Therefore, such colonies should be a “wildlife management priority,” they write. They don’t come out and say it but the implication is that feral cat colonies should be exterminated.
But feral cats, some animal rights advocates argue, are simply trying to eke out a living in a tough, unloving world. As the Humane Society explains, simply removing the cats may not be the most efficient means of solving the problem because cats that are inevitably left behind repopulate the colony, surrounding colonies may move in to replace the old and “the ongoing abandonment of unaltered pet cats…can also repopulate a vacated territory.” Feral cats, after all, are the “offspring of lost or abandoned pet cats or other feral cats who are not spayed or neutered.” Targeting irresponsible humans may provide a different solution, although spay/neuter laws are controversial.
In Washington D.C. alone, for example, there are more than 300 known feral cat colonies. Wildlife are victims of this problem, but feral cats are too as conditions for survival are tough. And as with so many other environmental banes, the root of the problem neatly traces back to a single source: humans. As the authors write in their paper, feral cats are the single greatest source of anthropogenic (human-driven) mortality for U.S. birds and mammals.