Behavior

The Cuckoos are Coming: Alaskan Birds, Wise Up!

Debbie Blicher is Senior Producer of Ray Brown's Talkin' Birds. 

As you may know, the Common Cuckoo and Oriental Cuckoo are brood parasites. That is, they lay their eggs in the nests of other birds, leaving their chicks to be raised by the unsuspecting foster parents. A cuckoo chick in the nest reduces the likelihood that the original chicks will survive, because female cuckoos time their egg-laying so that their chicks hatch first...and then shove the other eggs out of the nest. 

In areas where brood parasites are common, host species often develop coping strategies. Some birds hide their nests, or nest at different times. Some attack the brood parasite before she lays her egg or abandon the nest once she's laid it. Others pierce the parasite's egg and toss it out of the nest.

But what about birds that live where brood parasites aren't common? A new study from the University of Illinois and the University of Tennessee, Knoxville shows that an invasion of cuckoos from eastern Russia might cause significant losses among Alaskan birds. Professors Mark Hauber and Vladimir Dinets led the study to learn what Alaskan birds do—or don't—know about coping with brood parasites.

Common Cuckoos and Oriental Cuckoos are occasionally sighted in Alaska. Most likely, they've gotten there from Beringia in eastern Russia. While there isn't solid evidence that cuckoos are breeding in Alaska, Hauber says "it's likely already occurring."

Researchers put two types of fake eggs into the nests of more than two dozen songbird species in both Siberia and Alaska. (The fake eggs resembled varieties of cuckoo eggs.) Common Cuckoos and Oriental Cuckoos have advanced into Siberia and now breed near the Bering Strait; in comparison, Alaska is new territory. The researchers made sure to test each nest with each kind of egg. After the usual losses from predation, they had data from 62 nests of 27 bird species. 

Fourteen out of 22 Siberian nesting pairs rejected the fake eggs, but only a single one of the 96 Alaskan pairs rejected the fakes. Hauber suspects this result indicates that Siberian songbirds have encountered cuckoos long enough to develop coping behaviors, but he's worried about Alaskan songbirds. "The North American hosts have no defenses against invading cuckoos. They will be parasitized."

We hope that future ornithologists will follow up to find out how the Alaskan songbird population distribution has changed—and whether any of them have wised up about cuckoos. 

Want to see the original article? Click here. 

 

 

Ravens Act Sneaky, Like People Do

Debbie Blicher is Senior Producer of Ray Brown's Talkin' Birds.

Think humans are the only creatures who can be sneaky? Think again: ravens can, too.

Imagining that others might have thoughts different from our own had been assumed to be a distinctly human ability. But new research from the University of Houston suggests that ravens can not only imagine what others are thinking but also change their own behavior according to what they imagine. Experts found that ravens hiding food were able to understand that they could be watched, even without seeing another bird, and behaved sneakily as a result.

Before you read on, you need to know that ravens hide food for later, a behavior called "caching." When they feed from an abundant source, they take some of the food with them and put it away, often in the ground, so they can return to it when times are lean. 

Researchers placed a raven in a room adjacent to a room in which someone (um, a human) pretended to prepare food. These two rooms were joined by a window and a peephole. 

When the window was closed and the peephole left open, the birds behaved as though they were being watched by a competitor: they hid their food quickly and did not return to a previous stash (which would reveal its location). When the peephole was closed, the ravens didn't hide food as quickly, and they'd use the stash multiple times. They would remain this unconcerned even when the researchers played raven sounds behind the closed peephole. In other words, the test ravens behaved differently only when conditions indicated that they were being watched.

This research matters because it demonstrates that ravens might be able to imagine what others are thinking. Until now, only animals closer to humans—such as chimps—had been shown to have this ability. 

Professor Cameron Buckner, assistant professor of philosophy at the university, says the study gives important clues to the ability of animals to engage in abstract thought and indicates that we humans are not the only creatures who understand that others have a conscious mind. 

If you'd lie to read more, here's a link to the study. 
 

New Zealand Yellowhammers "Speak" with Obsolete Dialects

Debbie Blicher is Senior Producer of Ray Brown's Talkin' Birds.

Our Talkin' Birds Senior Producer, Debbie Blicher, learned to speak Portuguese in the Amazon rainforest outside the city of Manaus, Brazil. The people in that region speak with an accent reminiscent of the 1500's, when Portuguese was first introduced. In other areas of Brazil, the accent has evolved because of influences from other languages, local fads, and the usual linguistic wear and tear, but the people around Manaus use a Portuguese that isn't heard anywhere else. Brazilians outside the Amazon region correct Debbie's accent—once they stop laughing.

Now, research is showing that Yellowhammers in New Zealand  also "speak" with an obsolete accent. A new study published in Ecography indicates that New Zealand Yellowhammers possess some dialects that their cousins in Great Britain no longer use.  

The Yellowhammer (Emberiza citrinella) is a farmland bird native to the United Kingdom, recognizable by means of its bright yellow head. It was introduced to New Zealand in the 1860's and 1870's. The research on their song involved a citizen science project in New Zealand and Great Britain (http://yellowhammers.net) coordinated by Pavel Pipek of Charles University in Prague (the first author). Volunteers collected and submitted recordings of singing Yellowhammers with smartphones and cameras. The Prague researchers then compared the patterns of Yellowhammer dialects in Great Britain to those in New Zealand. They discovered that the birds in New Zealand use song structures no longer used in the UK. In fact, the New Zealand birds had almost twice as many dialects as their British relatives.

Why?

Pipek's team supposes this shift of dialects has something to do with the processes of the bird's population growth and decline. Over 600 Yellowhammers were introduced to New Zealand in the 1800's, where they reproduced so rapidly that they became pests, taking their songs wherever they went. Meanwhile, the Yellowhammer population in the UK dwindled, and some dialects died out with them. The result? Dialects are thriving in New Zealand that haven't been heard in the UK for up to 150 years—"a living archive," as co-author Dr. Mark Eaton says.

So next time you hear a Yellowhammer with an obsolete accent, don't laugh, and don't correct it. It's just saving a song from extinction, okay? Sheesh.

Birds Plan Their Flight Path on the Wing

You round a corner onto a city street, and you realize you need to drive between a bunch of trucks parked on the right and the busy traffic lane on the left. So what do you do? You slow down and drive carefully, adjusting your speed as you go. 

Research at the Queensland Brain Institute (QBI) has shown that birds will interrupt their wing beats to raise their wings or tuck them against their bodies when flying through a narrow gap, reducing their width very precisely. (Don't you wish you car could do that?) But it also shows that they don't slow down while making these adjustments. So how do they manage to make them at the right time? 

Researchers QBI's Visual and Sensory Neuroscience Laboratory analyzed the flight of budgerigars—parakeets (Melopsittacus undulatus)—as they flew through narrow gaps of varying width. Dr. Ingo Schiffner and Hong Vo filmed the birds, then did 3D reconstruction of their flight, which revealed that the birds seemed to plan ahead—1.4 meters ahead, in fact. (That's about 4.6 feet). And they even knew to fly a little higher because they'd drop later when interrupting their wingbeats. In other words, the parakeets made flight decisions well in advance of the obstacles. 

Even though the birds did some fancy flying, they didn't slow down. In another study, when parakeets flew through gradually tapering tunnels, they switched between what looked like two pre-set speeds, which Dr. Schiffner refers to as "low maneuvering" and "high cruising," bearing out the finding that they seemed to plan ahead, seeing and estimating the width of the tunnel.

This research might be especially helpful as we (humans, that is) design and build aircraft capable of unmanned flight. Current guidance systems are based on research in insects, but birds seem to have a different set of capabilities. 

The research is published in Biology Letters and  Scientific Reports.

Mother Fairywrens Teach Chicks in Their Shells

We posted last week about adult male Zebra Finches teaching their young with "baby talk." Now here's another post about bird learning, this one about how the mothers of two species of fairywren call to their chicks even before they hatch—and yes, the unborn chicks seem to learn the call. 

Before you get too skeptical, remember that recent research has demonstrated that human babies can learn speech sounds at 30 weeks of gestation—that is, before they're even born. 

Now, to birds. Nine species of fairywrens live on the Australian continent, where they frequently show up in suburbia. They're small songbirds, and the males are often deep blue or red. Diane Colombelli-Négrel and Sonia Kleindorfer, of Australia’s Flinders University, performed a series of experiments on the Superb Fairywren (Malurus cyaneus). 

First, they discovered that Superb Fairywren embryos seem to pay attention when their mothers call to them: their heart rate lowers, just like it does in humans and other animals when they're paying attention. The researchers then investigated the heart rate in a different fairywren species, the Red-backed Fairywren (Malurus melanocephalus). They were joined by Jenélle Dowling and Mike Webster from the Cornell Lab of Ornithology.

Female fairywrens start calling to their unhatched chicks soon after they finish laying, and they stop calling several days after the eggs hatch. Later, when the hatched chicks beg for food, they make some of the same sounds they heard in the egg. The obvious question is, do the chicks really learn their mother’s calls, or do they make these sounds by instinct? 

To answer this question, the researchers switched Red-Backed Fairywren eggs among a group of nests to see whether the chicks would call like their genetic mothers (by instinct) or like their foster mothers (by learning). It turned out that the chicks' calls were more similar to those of their foster mother. 

Why have a similar call? Well, the next study determined that Red-backed Fairywren parents give more food to chicks whose calls are similar to their own. Since cuckoos often lay eggs in fairywren nests, having a "password" can help parent fairywrens know which chicks are theirs. 

Next, the researchers investigated whether adult fairywrens retain any of the call information they learned in the egg. It is commonly believed that chicks don't start learning their adult songs until they're at least 10 days old. With the aid of computer acoustic analysis, the researchers found that the songs of young adult fairywrens more closely resembled the songs of their mothers than they did any other females in the same population. This "family resemblance" might help fairywrens recognize one another so they can share information about resources and dangers. It could even help prevent inbreeding. 

These startling discoveries about in-egg learning are just the beginning of what could be further study in embryonic learning in other birds and mammals. 

Check out this article from the Cornell Lab of Ornithology for more details on the fairywren research and some awesome sound. 

Adult Birds Use "Baby Talk"--and Babies Pay Attention

New research shows not only that baby birds learn songs best if they're tutored, but that adult birds seem to modify their songs the way we humans use baby talk. Further, activity in the babies' brains may have implications for research in attention issues in people. 

Birds do not hatch knowing how to sing. Like humans, they need to learn how to vocalize in socially meaningful ways. While it is known that baby birds learn from adults, Jon Sakata and his team of biologists at McGill University wanted to find out whether an adult needs to be present for the best learning or whether simply hearing the song is enough for baby birds. In other words, they wanted to find out whether the social connection matter when it comes to teaching.

For this study, male Zebra Finch chicks were observed learning songs from adult males either in person or by recording. (Why Zebra Finches? Because they breed well in the lab. And why just males? Because the males are the primary singers of the species.) The chicks, who had been cared for only by females prior to the study, were exposed for varying amounts of time to males singing in two different conditions. One group of chicks were tutored by a male in person; the other heard him singing to chicks in another room. The results? The chicks tutored in person learned their song more accurately no matter how long they were exposed to it. Further, the chicks who paid the most attention learned the best.

But the chicks weren't the only ones paying more attention. The males doing the tutoring took extra care when singing to their pupils. They repeated the beginning of the song, slowed down their phrases, and cleaned up some stray sounds. If you've ever spoken to a young child, you know exactly what these adults did. Further research is needed before anyone knows whether the adult males made these changes deliberately.

One last item of interest: the brains of the chicks who learned in person showed activity in two regions that showed no activity in the chicks who learned by recording. That is, the social activity of being taught in person seemed to activate mechanisms for attention. The research continues in order to identify just what those mechanisms might be.

What to know more? Read the abstract of the original study in the Proceedings of the National Academy of Sciences. The Washington Post has a nice article, too, complete with sound samples.

Urban Birds Aren't Scaredy-Cats

If a city crow and a country crow were presented with almost any object they'd never seen before, both of them would be scared of it. The exception? Trash. The city crow would have learned what trash is, perhaps even that it can sometimes harbor tasty snacks. A recent study in Animal Behavior gives the details. 

Researchers at Exeter University offered food to a variety of urban and rural birds, sometimes placing it near unfamiliar objects to see how they would respond. All the birds were more afraid to approach the food when an unfamiliar object was nearby than when the food was alone. However, all the birds were less afraid if the object was familiar to them. That's the first finding of this study: birds seem to remember things they've seen.

The second finding of this study: Of all the birds tested, corvids (crows, ravens, and magpies) were the most cautious—that is, unless they came from an urban environment. In other words, corvids who had lived with trash weren't too scared of it. Apparently, they had learned about it.

Why does this study matter? Because we humans are increasingly altering the earth. It is likely that the birds and animals that can adapt will stand the best chance of surviving as their environment continues to change. Study co-author Dr Alex Thornton puts it this way: “Animals’ responses to novelty can dictate whether they perish or thrive."

We here at Talkin' Birds frankly would prefer not to lose any species. So, while we truly appreciate animal learning, we sincerely hope that humans learn better means of coexisting with wildlife. 

City Lights Throw Migrating Birds Off Course

New research out of the University of Windsor indicates that bright city lights may cause migrating birds to zigzag rather than follow the (darker) course they might otherwise take. 

The team, headed by professor Dan Mennill, began their research by accident. Sound recording boxes had been placed around the area during a migration study, and the team noticed that the ones situated near well-lit—urban—areas picked up more bird vocalizations than the ones in dark—rural—ones. Further analysis revealed that more than three times the number of vocalizations occurred in the lit areas than in the unlit areas, indicating that three times more birds passed through the former than through the latter. Why? Perhaps because the lights made it difficult for them to see the stars by which they'd ordinarily navigate. 

Being drawn off course causes two problems for migrating birds. First, flying a less-than-direct route uses more of a bird's energy stores than flying a direct route; therefore, birds arriving at their destination are more depleted than they ought to be. Second, flying in a zigzag takes longer than flying directly, which means birds arrive later than they otherwise would—and perhaps miss a key food source or mating period. 

What can we do to help restore natural migration routes? For starters, we can turn off any unnecessary outdoor lighting at night. Mennill's team is researching other options, such as changing the intensity of street lights. Whatever they come up with, we're all for it. 

Nest-Building Lessons

Most birds build nests, but how do they know how to build them? It's not like there are published blueprints. Very little research has been done on how nest-building birds know what they know, but here's an intriguing study. 

Male Zebra Finches build circular, domed nests for their mates and chicks. New research at the University of St Andrews, Scotland, shows that Zebra Finch males learn to build these nests at least partly by watching other Zebra Finch males. However, they'll imitate only the males they know. 

Scientists in the School of Biology paired up female Zebra Finches with males who had never built a nest. Each pair watched the male of another pair build a nest; this male was either known to them or a stranger. While building, this male used pink or orange string, colors that Zebra Finches don't normally use. (How they got him to use those colors isn't explained. Our guess is they had him read a 1970's issue of Architectural Digest.)

When the time came for the newbie nest-builder to build his first nest, he used the same color string as the male who demonstrated--but only if the demonstrator was a familiar bird. If the demonstrator wasn't, then the newbie did not make the same color choice. 

The experiment showed that birds will turn to public information when they need to decide which materials to use to build their first nest, but only if they know the individual who provided the information. We think birds could teach human students a thing or two about doing research for school papers with Google. 

Dr Lauren Guillette of the School of Biology, lead of this study, suggests that birds might learn from one another in a way that resembles human beings' learning culture.  "This is called ‘social learning’, and can save time and effort for first-time nest-builders....Perhaps surprisingly, the birds did not always use this ‘advice’, especially if it came from a stranger. In humans, learning from those we know is one way that cultural traditions are formed, from the tools we use to the clothes we wear or the music we listen to.”

Want to read the original article? Find it here. 

Ray on NPR Discussing Weird Bird Behavior

One of the things we love about birds is that they demonstrate an immense variety of survival strategies. Since they live all over the world, in all kinds of conditions, they have had to develop ways to cope. Recently, Ray spoke with NPR's Lourdes Garcia-Navarro about some of the more bizarre behaviors observed in birds. Listen here for this brief, fun interview. 

How Zebra Finches Choose their Valentines

Like many birds, Zebra Finches tend to pair up and stay paired. However, how they choose their mates is a bit of a mystery. 

Whereas many animals choose their mates for certain physical traits, Zebra Finches don't seem to do so. Malika Ihle and her colleagues at the Max Planck Institute for Ornithology, in Seewiesen, Germany recently published their research into what makes Zebra Finches pair up. 

The studied 160 single Zebra Finches, allowing groups of 20 males and 20 females in an aviary to become acquainted with one another. Grooming is a sign of Zebra Finch courtship, so when pairs started grooming each other, the researchers knew that those birds were capable of pairing. They let half the couples stay together. The other half they divided into "arranged marriages." They caged all the pairs for a few months so they could develop relationships, then released them into a group aviary to raise their families. 

Over the following five months, the researchers observed as the pairs went through three breeding cycles. Then they repeated the experiment, this time allowing only one third of the birds to stay with their mates. 

The results? Couples who had chosen each other had 37% more surviving young than those who had not. Forced couples produced more unfertilized eggs, lost more eggs, and had more chicks die after hatching. Females in forced pairs were not as interested in mating as those who had chosen mates. Males in forced pairs were less interested in caring for chicks and more interested in mating with other females. 

Dr Ihle and her colleagues say that, if the finches were choosing mates for genetic reasons, more embryos would have died from defects caused by interbreeding between such a limited selection of partners. However, the difference in the survival of chicks appeared to depend on how well they were cared for by their parents. The researchers argue that the results they saw indicate that Zebra Finches select their mates based on how well they get along. We here at Talkin' Birds don't think that's a bad way to choose. 

 

 

Female Songbirds: Quiet for Good Reason

Female birds are capable of song in 71% of songbird species, So how come we don't hear them as often as we hear the males? New research indicates that sometimes female songbirds have good reasons to stay quiet. 

Sonia Kleindorfer, a behavioral ecologist at Flinders University in Adelaide, Australia, studied the singing patterns of female and male Superb Fairywrens (Malarus cyaneus), a small Australian songbird species. Like the females of many species, female Superb Fairywrens often sing for territorial defense, sometimes even when they're on their nests. They use a melody known as a "chatter song." The male uses it too, but he is not as often near the nest when he sings.  This is a key difference, since singing alerts predators such as rodents, cats, and foxes. Kleindorfer investigated whether male singing or female singing poses a greater risk.

During the nesting seasons of 2013 and 2014, Kleindorfer and her colleagues monitored male and female singing on and near 72 wild Superb Fairywren nests, as well as the eggs and chicks in the nests. The scientists counted a nest as “attacked” if eggs or chicks vanished in under 25 days. In other words, if eggs disappeared unhatched or chicks disappeared before they were capable of fledging, researchers assumed they'd been eaten. 

Kleindorfer's team leaned that both males and females sang the chatter song more often when they were just beginning to nest. They sang it less often when they had eggs and chicks in the nest, and with one major gender difference: The males sang away from the nest and the females near or inside it. In fact, some females never sang at all, and some sang only in response to their noisy mates. To put it differently, the females sang less when doing so would endanger their nests. Proof? The scientists baited artificial nests with quail eggs and broadcast female chatter songs infrequently (six calls per hour) and frequently (20 calls per hour). Predators ate the eggs at 40% of the "frequent" nests, but at only 20% of the "infrequent" nests: the quieter nests were safer for the kids. 

Jordan Price, a behavioral ecologist at St. Mary’s College of Maryland, posits that danger to the nest could be the reason that female songbirds of other species sing far less than their partners—or not at all—when they're the primary on-nest parents. It's even possible that, generally, male songbirds sing not to attract mates but simply because there's no reason for them not to. The females, on the other hand, have to be more wary. 

Zebra Finch Pairs Seem to Discuss Child-Rearing Inequalities

Like humans, some bird species mate for life and rear chicks together. But do they squabble like we do when one partner seems to be slacking off? The answer seems to be yes.

A forthcoming article in the Biological Journal of the Linnean Society describes research on vocalizations between Zebra Finch mates (Taeniopygia guttata) when they're incubating eggs. Zebra Finch couples share all chick-rearing responsibilities, including sitting on the nest before the chicks hatch. They sit in shifts about a half-hour long; while one sits, the other goes in search of food. When it's time to change shifts, the finches have what sounds like a conversation. Researchers were curious about whether this finch-to-finch conversation would change if one spouse were late returning to the nest for his or her turn. 

Working with twelve pairs of Zebra Finches incubating eggs in a large aviary, researchers trapped the male of each pair at the beginning of a foraging shift and detained him for an entire hour. Remember, his spouse was home on the nest, expecting him to return in a half hour. She did not leave the nest while waiting. Instead, she and the male had a, um, rapid conversation when he finally returned, vocalizing at each other faster than usual. (We imagine a heated argument.)

Are you wondering whether a female took extra time away from the nest if her spouse came back late? The answer: only if the male didn't talk with her much. If the late-arriving male initiated only a short conversation, the female would fly off for up to an hour. However, if the male took the time to "talk" longer with the female, she'd come back in 30 minutes. In other words, it looked as if the female got back at the male only if both spouses did not talk long enough to sort things out. 

No word on what the unhatched chicks thought about these delayed arrivals and arguments. Perhaps a next-generation study is in order.