Wild Things Has Moved To Science News


I am pleased to announce that this blog has moved to Science News magazine’s brand new website, which just launched today (it’s still trickling through the internet, so don’t be surprised if you see a security notification or get another little hiccup). I’ll still be writing about all the weird and wonderful stuff I come across, just in a different place. Come check out Wild Things and the site’s other blogs — including Gory Details by Erika Engelhaupt and Growth Curve by Laura Sanders — as well as Science News’ other fabulous science content.

Image courtesy of flickr user Benh LIEU SONG

Cats And Coyotes Divvy Up The Chicago Suburbs

coyoteI’ve been to Chicago and the surrounding area plenty of times, but I never thought to look for coyotes. I hadn’t realized that the animals have been expanding their territory over the last several hundred years, and they can now be found in many U.S. and Canadian cities, including Chicago. In many of these areas, coyotes are now the largest carnivores, at the top of the food web. And that might be affecting some of the animals we are more familiar with.

Urban coyotes have a varied diet, consisting mostly of small rodents, white-tailed deer, fruit (carnivores aren’t strictly meat eaters), bunnies and birds. They also eat a small number of cats, which led a group of scientists who are studying urban coyotes in the Chicago area to look into how coyotes and feral cats interact in the city’s suburbs. The results of their study appear in PLOS ONE.

feralcatBetween February 2008 and September 2009, the researchers captured 43 cats in eight sites in the suburbs west of Chicago. They then took blood samples from the cats and fitted 39 with radiocollars (two cats were thought to be pets, one was too small for the collar, and one was so sick it was euthanized). Getting good data from the cats was difficult: A fifth of the cats died during the study period, a quarter were adopted, 13 percent had collars that didn’t last until the end of the study, 10 percent were never heard from again, and, in what is the most mysterious statement in the study, 23 percent “were removed from the system by cat advocates opposed to our research.” Despite the difficulties, however, the researchers were able to get good tracking data for a number of kitties, enough to map out several cats’ home ranges and plot them against the ranges of coyotes in the urban coyote project.

The cats and coyotes, the researchers found, did overlap a bit in their travels, but for the most part, cats stuck to areas around homes and buildings. The coyotes, in contrast, preferred natural habitats away from human development. “Coyotes in our system appear to inhibit cat use of the natural habitat fragments through a combination of predation and cat avoidance of coyote activity,” the researchers conclude. “It is clear the two species are largely separated across the metropolitan area.”

This is only a small study, but the team speculates that coyotes may be controlling the feral cat population throughout the Chicago area, keeping the cats out of the fragments of natural habitat that dot the suburbs. If the pattern holds in other areas, then in regions where coyotes can be found, the ecological impacts of cats (that is, the cats’ killing of birds and other native wildlife) might be overestimated. Cats have gained a reputation for being evil murderers that devastate wildlife, but we’re finding that the story is far more complicated. And its one that needs to be better elucidated.

Images courtesy of flickr users John Picken (Chicago coyote, top) and cats marcoff (Chicago feral cat, bottom)

The Chickens of Kauai


If there’s a soundtrack to the Hawaiian island of Kauai, it’s not waves or the songs of a native bird or even hula music — it’s the crow of the cock. Everywhere I’ve been on Kauai, from the beach to the town to the mountains, there have been chickens.

The chicken population on the island exploded more than 20 years ago, after Hurricane Iniki, which devastated several Hawaiian islands. On Kauai, one of the lesser effects was that the storm blew apart chicken coops — possibly many housing fighting chickens — and released the birds into the wild. It’s not all that surprising that the birds then thrived because their wild ancestor, the red jungle fowl, lived at similar latitudes in Southeast Asia.

(You might think that all those chickens would be a great source of food for the local people, but I’ve been told that the birds are hard to catch. Chickens can see and keep track of four things at once — up and down and with each eye — so it’s hard to sneak up on one. Plus, the meat is tough. I suggested to one local that he try coq au vin — the traditional French method of cooking an old bird — but he looked at me like I was nuts. I still maintain, though, that even if it’s not a local dish, cooking a chicken in lots of wine, and maybe some garlic, would sure be tasty.)

Chickens are just one of the non-native species that have spread across Kauai, and one of the less destructive ones. I visited with Diane Ragone, head of the Breadfruit Institute, this week, and she noted that while most people look at this island and see nothing but lush green mountainsides, she sees lands bare of native plants. And then there’s all the invasive animals. I found a couple of adorable young feral cats at the end of the road (literally) on the North Shore of the island and winced when a woman started feeding them. I don’t want kitties to die, but they are a huge problem on islands like this one because they kill native birds. And here there are some spectacular birds, such as Laysan albatrosses and red-footed boobies. Feral pigs now roam the island, causing all sorts of damage. There’s even deer that have been purposely released so people can hunt them. There’s a flock of parrots that derive from someone’s lost pets.

One of the things that has struck me since I’ve been here is how most tourists will never realize that the island has changed dramatically in the last couple of hundred years, since the first Europeans arrived and began introducing all these non-native species. Kauai is beautiful now and truly lives up to its nickname as the “Garden Island,” but what must it have looked like before all of this changed?

Photo by the author

A Tiny Frog That Should Be Deaf Hears With Its Mouth

GardinersFrogFar away on the islands of Mahé and Silhouette in the Seychelles in the western Indian Ocean can be found one of the world’s smallest frog species, Gardiner’s frog, just 10 to 11 millimeters in length. These fogs should be deaf, because they lack a middle ear (in humans, that’s the bit with the eardrum). That part of the ear is thought to be a necessary adaptation to life on land, helping sound to make the transition from air to tissue, where it can be translated into nerve impulses that reach the brain. But Gardiner’s frog has evolved a different method for hearing — it uses its mouth, reports a team of French researchers in a new study in PNAS.

Scientists had been somewhat perplexed by Gardiner’s frogs because, despite lacking the necessary equipment for hearing, the amphibians appear to have no problems communicating. The French team began by recording calls from frogs on Silhouette and playing them back over loudspeakers to frogs in their natural forest habitat. When a male heard the call from one of its own species, it called back a response. But the frogs didn’t respond when they heard sounds from other species. They were definitely hearing and well enough to make species distinctions.

Dissecting the frogs might be a classic technique in the classroom, but here it just wasn’t an option; these frogs are far too small to see anything useful with dissection. Instead, the researchers used a technique called X-ray synchrotron holotomography to image the frog’s inner anatomy. Then they used that data to create a computer simulation of the amphibian and determine how the sound was traveling through the frog’s head.

Previous studies had suggested that sound passed through the lungs on its way to the inner ear, where it would be translated into nerve impulses. Another theory was that sound was conducted through the animal’s bones. But the computer simulations revealed that the mouth (or oral cavity as the scientists name it) is actually the ideal anatomical structure for amplifying sound. The cavity resonates sound at a frequency that nearly matches the frequency most commonly found in the frogs’ calls. The researchers also found that the tissue that separates the inner ear from the inner mouth in Gardiner’s frogs is very thin, and there are fewer layers of tissue, which helps the sound to pass through.

The frog’s mouth might also play a role in determining the direction of sound, the researchers suggest. And, they note, this discovery shows that the middle ear isn’t quite so necessary for life on land as had been thought.

Image credit: R. Boistel/CNRS

Sea Otters Again Prove Their Worth

seaotterIf you take a class in ecology, sea otters inevitably come up. They’re a classic example of a keystone species — that is, an animal or plant or other organism that has a critical role in the ecosystem such that, if you take it out of the system, everything collapses. Sea otters are a keystone species in the kelp forests off California. If the sea otters aren’t around to munch on sea urchins and keep the urchin population in check, urchins proliferate and graze the kelp to death. Without the kelp, other animals that depend on the vegetation — including crabs and geese — suffer. All that happens because there are no sea otters.

Now a group of scientists from California have found that sea otters play a similar keystone role in another coastal California ecosystem — the seagrass beds of Elkhorn Slough. The study was published this week in PNAS.

Elkhorn Slough is an estuary near rich fields of strawberries and artichokes. Those farm fields are a problem because when water drains off them into the estuary, it carries nutrients (from fertilizer) and pesticides. Nutrient loading is a particular problem in marine ecosystems as it changes the abundance of certain organisms and sets everything out of whack in the food web. Some critters thrive, but many suffer. And in Elkhorn Slough, seagrass beds have been on the decline.

Scientists suspected, however, that sea otters may play an important role in this area. When the researchers looked at a 50-year record of nutrient levels, seagrass and sea otters, they noticed a pattern. There were no sea otters in the area between 1965 and 1984. During that time, when nutrient levels started to increase, the seagrass beds declined. But when the sea otters were reintroduced to the area, the seagrass beds again thrived, even though the nutrient levels continued to increase.

The researchers suspected that the link between the sea otters and seagrass was not sea urchins, as in the kelp forests, but crabs: The sea otters eat the crabs. Without so many crabs around, grazing herbivore species thrive. Those grazers eat algae that lives on and harms the seagrass, and as a result, the seagrass thrives.

But when there are no otters around, this all falls apart. The crabs outcompete the algae grazers, letting the algae proliferate. And with the nutrients boosting the algae population, the seagrass beds suffer.

“This estuary is part of one of the most polluted systems in the entire world, but you can still get this healthy thriving habitat, and it’s all because of the sea otters,” study author Brent Hughes of the University of California, Santa Cruz, told BBC News. “So it’s almost like these sea otters are fighting the effects of poor water quality.”

This new pattern is a bit more complex than the classic sea otter–kelp story, but it’s yet another example of how important top predators are and the disaster that can follow their removal.

Image courtesy of flickr user Blake Matheson

Secrets Of A Cape Fur Seal Pup’s Coat

sealA Cape fur seal doesn’t become a marine mammal until it is several weeks old, spending that time only on land. Stuck on shore with little shade available, the pups have to endure the hot sun, usually unable to take a quick dunk to cool off as its parents would do because the waters are too dangerous. So how does a pup cool off? It doesn’t have to, say scientists reporting in PLOS ONE. When they’re young, these animals have a special coat that keeps them cool.

The researchers studied six Cape fur seal pups that were born between 2010 and 2012 at Zoo Rostock in Germany. They measured the pups’ surface temperatures with an infrared camera as well as skin temperature and rectal temperature with increasingly invasive techniques (there’s never going to be a good way to get that last one remotely).

As long as a pup’s fur was dry, it was able to maintain a stable internal body temperature. But when a pup got wet — when its mom took it for a quick dunk, or it rained — its hair became flattened and stringy, and the pup’s body temperature dropped. Sometimes they shivered. (Adorable note: The pups would shake themselves like dogs when they came out of the water.)

The researchers conclude that the pup’s fur is adapted to the terrestrial lifestyle that marks these animals’ early lives. The fur traps a layer of air near the skin that insulates against heat and cold. The tradeoff is that this fur doesn’t insulate well in water. This fur coat has to change as the seals age and adapt to the marine life.

The fluffy fur may protect a seal pup against the heat, but it’s made it vulnerable to human predators. The Namibian government lets people kill 80,000 Cape fur seal pups each year; a pelt can be sold for $7.

Image courtesy of flickr user DragonWoman

What’s A Manatee Doing In Virginia?

manateeVirginians are excited this week because a manatee has come to visit. It was spotted this weekend in the Appomattox River (see video below). Manatees are residents of Florida, so what’s this one doing so far up the East Coast? Well, it’s not actually all that far out of its territory if you consider that manatees have swum as far north as Cape Cod. It seems that sometimes Florida’s state marine mammal likes to wander. But why?

Well, no one has ever asked the manatees (or if they have, they never got a good answer), but news reports describing various incidences of manatees in the north have plenty of speculation: The AP report about Virginia’s current visitor, for example, says that manatees sometimes leave Florida when waters there get too warm; they go north to cool off. A 2006 story about a Cape Code manatee says that it’s common for manatees to travel up to the shallow areas off the Carolinas. USGS wildlife biologist Cathy Beck speculated that the manatee followed a warm current up the coast to Massachusetts.

Manatee sightings north of the Carolinas are not uncommon these days. Baltimore has even had a repeat visitor, nicknamed Chessie, that has shown up multiple times since 1994. But whether more manatees are swimming north in the summer or more people are noticing them isn’t known.

But for now wandering manatees are just an interesting oddity, and perhaps a distraction from the bigger problems that the species faces. See, the Florida manatee (a subspecies of Trichechus manatus) is in trouble. The IUCN lists them as endangered and says there are fewer than 2,500 individuals. More than 200 manatees died in a deadly algal bloom earlier this year. They’re victims of habitat loss and often in conflict with the fishing industry (manatees get entangled in fishing gear). Boat collisions are also a huge danger. In 2010, for instance, 83 animals were killed in encounters with boats. One newspaper estimated that this year manatees are dying from all these various causes at a rate of 100 per month.

Some groups in Florida have petitioned to have the manatee’s status upgraded from Endangered to Threatened, noting that aerial surveys of the animals show that the Florida population has increased in recent years. But Caryn Self-Sullivan, a conservation biologist at Nova Southeastern University in Florida, argued in a blog post earlier this year that there’s little reason to change the mammal’s classification. Aerial surveys don’t produce reliable counts; mild winter conditions and poor visibility can skew the results. And changing the manatee’s status to Threatened would still indicate that they were in danger of extinction and in need of protection. “To reduce protection would likely produce a significant and deleterious effect on the manatee population in Florida,” she writes.

Classifying the manatee as Threatened wouldn’t immediately change any of the laws that protect the animals. But this is all moot for now; the reclassification discussion is on hold. That would seem to be good news, except that the hold is in response to this year’s high death rate. Manatees just can’t get a break.

Image courtesy of flickr user NOAA’s National Ocean Service; video from cody_beeler on Instagram

National Zoo Brings On The Babies

There are many reasons to love the Smithsonian National Zoo, but the constant influx of cute babies is definitely one of them. This week the zoo’s female Sumatran tiger Damai gave birth to two cubs, and it’s a good thing it’s August in DC as I’m sure productivity has taken a dive from people watching the tiger cub cam. In honor of the new cubs, I decided to distract everyone a bit further and put together a slideshow of the zoo’s cuteness.

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All images are from the Smithsonian National Zoo flickr page

Spider’s Jump Stabilized By Silken Line

Human jumpers are pretty pathetic when compared to jumping spiders. These arachnids can hurdle themselves to destinations of various heights and cover distances up to 25 times their own body length. That’s like a six-foot-tall man jumping 150 feet, starting from a standstill.

Most jumping spiders attach a silk dragline to their starting point, which was thought to be a safety line. That line has a second purpose, researchers have just found — stabilization. They report their findings in the Journal of the Royal Society Interface.

The team of researchers from Taiwan captured 27 Adanson’s house jumpers (Hasarius adansoni) near Taichung City. Twenty-two of the spiders deployed silk when they jumped, and five did not. The five that didn’t use silk ended up being natural controls in a jumping test, letting the researchers compare jumps with and without silk. The scientists had each of the spiders leap three times, filming them with hi-speed cameras (see video above for an example of a jump).

Spiders that used a dragline had a stable body position in the air and a smooth landing. Those that didn’t, however, pitched rearward in the air and landed more upright, falling forward and slipping or tumbling as they made contact with the ground.

“These results suggest that dragline silk can function as a body stabilizer to prepare salticids [jumping spiders] for a predictable, optimal landing posture,” the researchers write, “and hence is critical for these agile and efficient hunters.”

Video from Kai-Chung Chi et al.

Baby Owls Are Adorable (Oh, And They Sleep Like Human Babies)

babyowlFirst, a little background on sleep: Sleep in mammals and birds has two phases, REM and non-REM. REM, which stands for “rapid eye movement,” gets its name from the quick and random movements the eyes make during this phase. REM sleep is the time of vivid dreams. Non-REM sleep comes first, though, and the body cycles through non-REM and REM sleep throughout the night. Adult humans spend about 20 to 25 percent of their sleep in REM. Newborn babies, though, spend half their night in the REM phase.

And so do baby owls, finds a new study published in Frontiers in Zoology. A team of scientists from Switzerland and Germany outfitted 66 barn owl nestlings with a small data logger that measured brain activity and head movements. The researchers recorded the owlets’ sleep for up to five days, then removed the equipment, letting the owls grow up normally.

In the owls, REM sleep lacks the eye movements that characterize this phase in humans. But the brain recordings revealed that the owlets spent about half their sleeping time in the REM phase. The brain activity was similar to when the nestlings were awake, a key sign of REM, and they nodded their heads slowly as they slept.

Image credit: Fabrizio Sergio