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

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

More Than Just Seagulls Munch On The Seashore

journal.pone.0068221.g005Walk along pretty much any beach and at the high tide mark will be a line of debris. There may be seaweed or shells, bits of driftwood or plastic debris. You probably won’t see any fish, though. And that’s a little odd, because fish do die, and their bodies have to go somewhere. Surely some would wash ashore.

A group of researchers in Australia think that they’ve figured out where the fish go – the fish quickly get scavenged by the critters that live along the shore. But there’s more than just seagulls finding their meals here, the team reports in PLOS One.

The scientists set up a series of experimental plots along a sandy beach on North Stradbroke Island on the east coast of Australia. They picked a spot far from humans, where dogs and beachgoers would be scarce. Then they set out 20 plots, three meters by 10 meters each, and for eight days added about five kilograms of flathead mullet fish to half the plots about two hours before sunset.

The beach was nearly picked clean. Over the eight days, 720 fish were set out and 97 percent were completely eaten. Gulls (silver gulls in this case) ate some of the mullet, but there were several other birds species as well: Torresian crows, whistling kites (b in image above), brahminy kites (a), and white-bellied sea eagles (c and d)

These avian scavengers scoured the beach most often at sunrise and in the first few hours of morning. On three occasions at night, however, red foxes (f) visited the plots, snapping up the easy meal. And on one day, a lace monitor (e) – a large, carnivorous lizard – was spotted on the beach snacking away. That was a surprise because there have been few reports of terrestrial reptiles scavenging on a beach.

One invertebrate also got in on the action. The researchers measured the diameter of ghost crab burrows and, using burrow size as a proxy for crab size, discovered that when they added fish to the experimental plots, bigger ghost crabs moved in to take advantage of the free food.

But birds were the dominant consumers of the carrion fish. And they probably play an important role in this seashore ecosystem, the researchers say, helping to transfer nutrients from the sea onto land and providing a vital link between water and soil.

Image used under Creative Commons license, Schlacher TA, Strydom S, Connolly RM, Schoeman D (2013) Donor-Control of Scavenging Food Webs at the Land-Ocean Interface. PLoS ONE 8(6): e68221. doi:10.1371/journal.pone.0068221

Andean Condors Eat Their Veggies

Figure 1

Everyone knows that vultures eat carrion, and Andean condors (Vultur gryphus) are no different from their scavenging brethren. The world’s heaviest soaring bird survives on a steady diet of rotting sheep, goat, rabbit and red deer, with the occasional horse or cow thrown in the mix. A group of researchers studying carotenoids — red and yellow pigments found in plants — in these birds, however, have come to the conclusion that condors are likely also eating a lot of vegetation. (The study was published last week by PLOS One.) That might mean they’re munching on some kind of plants, or it could be that they’re finding, as the scientists put it, “vegetal content” in the herbivores they eat, that is, whatever the birds come across in the stomach and intestines. Yum.

Andean condors may have need for carotenoids in their diet: Males of the species (above, a) have a brown iris in the eye, and neck wattles and skin on the head that can vary in color from gray to yellow. Females (b) have a red iris and less yellow skin (and no comb). During arguments over carcasses, the bare skin of grown and nearly grown condors can change in a moment from pale to deep yellow or orange or red (c and d). All that color requires pigment.

But how do they get that pigment, the researchers — a team from Spain and Argentina — wondered. They took blood samples from 22 wild Andean condors and 17 American black vultures in Patagonia in 2010, along with 27 captive condors from the Buenos Aires Zoo. The American black vultures are a much plainer species, and they wouldn’t seem to have as great a need for carotenoids. And the captive condors were fed a diet of meat only; if they had fewer of the pigments in their blood, then it would mean the wild birds were getting their colors from something other than herbivore flesh.

The wild condors and the black vultures, living in the same area, ate pretty much the same meals, but the condors had three times the concentration of carotenoids in their blood. The wild condors also had higher concentrations than their captive counterparts. The captive birds did have some carotenoids in their blood, but it was at lower levels.

The researchers concluded that the captive condors are getting some carotenoids solely from the herbivore meat they eat. But the wild birds are probably getting a lot more by eating “viscera and vegetation.” The Andean condors may also be biologically more competent at taking up or accumulating the chemicals than the black vultures, a necessity since they have a greater use for them.

But an analysis of 135 pellets (i.e., regurgitated food) taken from communal roosts gives added evidence that the wild birds are getting their carotenoids from vegetal matter of some sort: About 35 percent of the pellets consisted of 80 percent or more vegetal remains.

If Andean condors do indeed have a taste for veggies, they wouldn’t be the first vultures to snack on the green stuff. Egyptian vultures, which have their own need for carotenoids to color their bright yellow faces, get their fix by eating herbivore poo.

Image used under Creative Commons license, from Blanco G, Hornero-Méndez D, Lambertucci SA, Bautista LM, Wiemeyer G, et al. (2013) Need and Seek for Dietary Micronutrients: Endogenous Regulation, External Signalling and Food Sources of Carotenoids in New World Vultures. PLoS ONE 8(6): e65562. doi:10.1371/journal.pone.0065562

Like Humans Waltz And Polka, Lyrebirds Match Dance To Tune

lyrebird1Not every song has its own specific dance, but there are certain tunes — from the tango to the Twist — that demand distinct moves. Now scientists have caught birds doing something similar: Male superb lyrebirds (Menura novaehollandiae) coordinate movement to the type of song they’re singing. The study appears in Current Biology.

Male superb lyrebirds sing and dance to attract the ladies, and their repertoire can contain more than 90 tunes. They don’t have such a big variety when it comes to dance moves, but with their elaborate tail feathers, these visual displays can be pretty spectacular. To study the song-and-dance combo, a group of Australian scientists filmed a dozen of these birds in Sherbrooke Forest in Dandenong Ranges National Park in Australia, east of the city of Melbourne.

Despite having such a large number of songs to choose from, only four tunes were accompanied by dance (you can see a video of one here); the researchers named those songs A, B, C, and D (not the most inventive names, but this is a scientific paper we’re dealing with). Each of these four dances had it’s own set of moves, the researchers write:

Our analysis revealed that each of the four song types within the display was associated with one particular gesture. The gesture accompanying song A consisted of steps, often to the side, with wings motionless and a wide tail. In contrast, the male’s tail was narrowed while he sang song types B and C, and during the latter he nearly always jumped or bobbed, and flapped his wings. When males sang song type D, the tail was usually wide and the legs and wings still.

“Just as we ‘waltz’ to waltz music but ‘salsa’ to salsa music, so lyrebirds step sideways with their tail spread out like a veil to one song—which sounds like a 1980s video-arcade game—while they jump and flap their wings with their tail in a mohawk position while singing a quiet ‘plinkety-plinkety-plinkety,’” study coauthor Anastasia Dalziell of Australian National University said in a statement.

lyrebird2While the lyrebirds sometimes sang each of these songs without dancing, they never danced without an accompanying tune. And occasionally, just like we do when dancing, the birds would mess up. The researchers say that this shows that the song-and-dance routine is difficult for the birds

How these birds develop their musical theater skills isn’t known, but the males spend years practicing before they reach the age of maturity. These skills are incredibly important, because females choose their mates after watching several males put on these displays. What the females are looking for, though, is still a mystery. Dalziell said, “Sometimes after what seems to me to be a perfectly wonderful display by a male, I watch a female leave and check out his neighbor.”

Images credit: Alex Maisey/Current Biology

Of Cuckoos, Cowbirds And Other Parasitic Birds

Earlier this month, a friend in Virginia attached a houselike bird feeder to one of the windows of her home. She was worried no bird would find it, but soon a finch moved in, made a nest and started laying eggs. My friend named her Molly.

But tragedy struck. While Molly was away one day, another bird visited the nest. That bird pushed out one of Molly’s eggs and laid one of her own. Molly returned, with little clue as to what had happened, and she now sits on a nest with four of her own eggs and one from the intruder:

With the event caught on a motion-capture camera, and the eggy evidence left behind, the parasite was quickly identified as a brown-headed cowbird (Molothrus ater). Cowbirds are brood parasites. Cuckoos are the best known of these kinds of birds, but others include indigobirds in Africa and the black-headed duck. These are all birds that lay their eggs in other birds’ nests. And some, like cowbirds and cuckoos, destroy eggs already in those nests, giving these tales an especially gruesome twist.

It’s hard not to judge creatures like that — the consensus on Facebook is that Molly’s cowbird intruder is a murderer — but the natural world is rarely fairy tale perfect. Brood parasitism is just another life strategy that creatures use to pass on their genes to the next generation. By laying her egg in another bird’s nest, the parasite can pass off the cost of child-rearing to the other bird and instead invest her energy and resources in mating and producing more eggs. The brown-headed cowbird, for instance, will produce an average of 80 eggs in just two years. (Female cowbirds are a little like chickens in this way; they keep producing egg after egg for two months so they can take advantage of all the available nests during that time.)

The tradeoff for this strategy is that only about three percent of cowbird eggs (2.4 eggs) will survive to adulthood. That’s despite a few advantages that baby cowbirds get: They usually hatch a day earlier than the other eggs in their nests. They tend to get more food than the other fledglings, probably because they’re louder and more demanding. And mom already offed some of the competition.

What does in many cowbirds is that mama birds aren’t discriminating when they pick nests in which to lay their eggs. Scientists have observed brown-headed cowbirds placing eggs in the nests of 220 or so other species, but these events have only been successful in 144 of those species.

The house finch — Molly’s species — is probably not one of them. A 1996 study in The Condor documented 99 cases in Ontario, Canada in which brown-headed cowbirds parasitized house finch nests. Almost 85 percent of the eggs hatched, but none were successfully reared. The researchers suspected that it was due to a mismatch in diet. Passerine birds like cowbirds prefer a diet of arthropods, but in a house finch nest they’re likely to only get seeds. The baby cowbirds don’t get enough nutrition in finch nests.

Most other brood parasite species won’t have such problems because they’re specialists and only use the nests of one other species. Their eggs may be adapted to look like the eggs of that other species, and their offspring might mimic the other nestlings. (Cuckoos don’t pick one single species to mimic, but they can match their eggs to those of several different species.)

The story of Molly’s family is still unfolding, but there is reason to worry further. Cowbird nestlings have been known to push eggs and nestlings out of the nest and to smother their nest mates. With the cowbird egg facing its own uncertain future, this could get ugly. Nature can be cruel.

Keep up with Molly on the Molly.Finch channel on Ustream.

Image courtesy of Kris Trader

Petrel Bones Show How Humans Changed The Open Ocean Food Web

Pterodroma sanchwichensisIn one marine biology class I took long ago, the way we study the open ocean was compared to trying to study a forest by throwing a bucket out of a helicopter as you fly over and making conclusions based on whatever you happen to drag back up. Ocean exploration these days is a bit more sophisticated, but it’s still not easy, especially if someone wants to see how things have changed over the last several thousand years or so. But scientists figure out elegant solutions to these problems.

In a study published this week in PNAS, a research team led by the Smithsonian’s National Museum of Natural History investigated how the food web of the North Pacific Ocean has changed since humans began fishing there on a large scale by looking at the chemistry of petrel bones. Hawaiian petrels turn out to be a good proxy for what’s going on in the oceanic food web for several reasons: The birds breed only on the Hawaiian Islands, and their remains, dating back thousands of years, can be found in many archaeological and paleontological sites there. That makes the petrels special because most creatures that play a role in the oceanic food web die at sea. Even better, these bones contain a record, in the form of carbon and nitrogen isotopes, of where they foraged and what they ate when they were alive.

“Hawaiian petrels spend the majority of their lives foraging over vast expanses of open ocean,” lead author Anne Wiley of the Smithsonian Institution said in a statement. “In their search for food, they’ve done what scientists can only dream of. For thousands of years, they’ve captured a variety of fish, squid and crustaceans from a large portion of the North Pacific Ocean, and a record of their diet is preserved in their bones.”

Three decades of collecting 17,000 petrel bones have given these researchers a pretty good dataset to work with. And when they looked at the isotope information from the bones, the scientists found that from about 4,000 to 100 years ago, petrels were munching on bigger prey. But when humans intruded on the food web, snapping up the bigger fish, petrels changed their diet and gobbled up smaller creatures.

“Our bone record is alarming because it suggests that open-ocean food webs are changing on a large scale due to human influence,” coauthor Peggy Ostrom, a zoologist at Michigan State University, said in a statement.

It’s yet another case showing how humans are influencing the planet, and not necessarily for the better.

Image courtesy of Brittany Hance, Imaging Lab, Smithsonian Institution

Not All Animals Make Great Moms, But These Do

I sent my mom a card for today that highlighted how turtles weren’t the best of mothers — they lay their eggs and leave. No turtles are known to care for their young. But there are plenty of animals, including humans, that make great moms. And the Smithsonian’s National Zoo published a bunch of pictures of them on flickr this week. Here are my favorites:


The zoo has two lion moms, Shera and Naba, who in 2010 gave birth to a total of seven cubs. That gave the zoo a full pride of lions. The family has since been split up, but it’s normal for young males to leave and go off on their own. (Photo courtesy of John McRay, Smithsonian’s National Zoo)


Shanthi gave birth to Kandula in 2001, the first male Asian elephant born in this country that was conceived through artificial insemination. (Although the real reason to include this photo is that my mom loves elephants.) (Photo credit Jessie Cohen, Smithsonian’s National Zoo)


White-naped crane Brenda is serving as a surrogate mom to this little one. The zoo has a captive breeding program for the rare birds in Front Royal, Virginia. (Photo credit: Chris Crowe, Smithsonian’s National Zoo)


Gorilla mom Mandara has had six kids over the years. Her youngest, seen here, is Kibbi, born in 2009. (Photo courtesy of Connor Mallon, Smithsonian’s National Zoo)


Sea lions make great moms, too. Here’s Cali with her two-year-old pup Sophie. (Photo courtesy of Mark Van Bergh, Smithsonian’s National Zoo)


Just like a human kid, sloth bear cub Hank tries to upstage mom Hana in this portrait of the two. While Hank is young, though, his mom will carry him on her back most of the time. (Photo courtesy of Connor Mallon, Smithsonian’s National Zoo)


Electra gave birth to two kittens last year, the first fishing cat to do so at the zoo. (Photo courtesy of Janice Sveda, Smithsonian’s National Zoo)

Happy Mother’s Day to all the world’s moms, human and animal!


Bad News For Animals That Live In The Subnivium

voleYou’ve probably never heard of the “subnivium.” That’s because it’s a term that scientists just made up (they do that). The group of ecologists and biologists, led by Jonathan Pauli of the University of Wisconsin, say in an article recently published in Frontiers in Ecology and the Environment that the subnivium is the seasonal refuge that occurs below the snow where there’s environmental stability. It’s cold there, with temperatures near freezing, but this region serves as a retreat from the harsh, sometimes changeable environmental conditions above.

A healthy subnivium contributes to a healthy ecosystem. Insulated soil lets microbes and fungi breathe and proliferate and process organic matter. Plants benefit from increased carbon dioxide and warmer temperatures, especially during late winter and early spring. Many animals — a list that includes invertebrates, amphibians, reptiles, birds, and small mammals — will use the region to hide out during the winter, feeding off each other or any vegetation they can find. There are whole ecosystems below the snow.

But warming conditions have led to many changes in the patterns of snow in the Northern Hemisphere (that’s where most of the world’s snow is found): The month of maximum snow cover has shifted from February to January. The spring melt is about two weeks earlier than it was decades ago. The extent of land covered in snow in the winter has been shrinking. In many places, the amount of time when snow is more likely than rain has decreased by more than one and a half months. Snow depths are decreasing, as are snow packs. The list goes on and on.

“Snow cover is becoming shorter, thinner and less predictable,” Pauli said in a statement. “We’re seeing a trend. The subnivium is in retreat.”

With all these changes, the stability that the subnivium provides is therefore disappearing. What does that mean for the ecosystems that thrive there? One worry is that organisms, such as plants, that are exposed to cycles of freezing and thawing could experience tissue damage. Others, like voles or insects, that lose the layer of snow that hides them may be subject to predation by birds or other critters.

“Decay of the subnivium will affect species differently, but be especially consequential for those that lack the plasticity to cope with the loss of the subnivium or that possess insufficient dispersal power to track the retreating range boundary of the subnivium,” the researchers write. Those that can adapt to the loss of stability or can move to places where there’s still reliable snow cover will do better than others. Adapt or move — those seems to be the only two options for surviving climate change.

Image of vole courtesy of flickr user musubk

To Count Bird Diversity In The Forest, Listen In The Morning

forestkingfisherIf you want to figure out how many different species of birds are in a forest, all you have to do is listen. But there are a few ways you can go about such a study: You and your colleagues can hang out in the forest for 12 hours a day, five days a week. Or you can set up microphones and record the forest sounds for analysis back in the lab, in which case you’ve got a few more options — let a computer listen and identify species, make your students listen to all of it, or listen to only some of the recordings.

But which way is best? The computer isn’t quite talented enough at this point, and though students are cheap, they’re not cheap enough to listen to all of the sound you’d collect. So the options are to count in person or listen to only some of the recordings. But which ones? And are they better than going into the forest yourself?

To figure that out, researchers from Queensland University of Technology in Australia set out to determine how many species of birds were in a eucalyptus forest in southeast Queensland. The study (in press) appears online in Ecological Applications.

They recorded five days of sounds from several sites in the forest and also had two experienced bird surveyors conduct on-site surveys of those areas at dawn, noon, and dusk for five days. Once the recordings were back in the lab, they were sampled in one-minute bites in five different ways (listening to recordings longer than 240 minutes is cost prohibitive and impractical for most researchers): randomly over the 24-hour period, randomly only in the three hours after dawn, randomly only in the three hours before dusk, randomly after dawn and before dusk, and every half hour over the full 24 hours.

Across all the sites in the forest, the researchers found 96 species using acoustic methods and 66 species with the traditional, in-person survey. And when they looked at their samplings of the acoustic data, they were able to find the most species in those three hours right after dawn, almost twice as many as can be found in the same time by the traditional method.

Sampling the recordings isn’t perfect — it doesn’t find all species, especially rare and cryptic ones — but the researchers say that using a computer to help identify the parts of a recording more likely to have a bird call would help avoid getting random samples of only wind. Thus, combining computer analysis with human listeners of these recorded forest sounds could help scientists get a better picture of biodiversity.

Relying solely on the computer to identify so many species isn’t an option for now, the researchers say, because the programs are plagued with false positives and negatives. However, one day they may get good enough that they can detect birds with high accuracy and cut out the need for humans to listen to hours of sound. (But there’s something about that that makes me a little sad.)

Image of a forest kingfisher courtesy of JJ Harrison, via wikimedia commons