Jordan Price is a spy. Armed with binoculars and a heavy-duty recorder, he embarks on his latest mission. He spots his targets, then quietly hides in a nearby bush, careful not to give himself away. Once he finds a suitable stakeout, he sets up camp. After all, he’s going to be there awhile—that is, if he wants to find out the latest scoop. He turns on his recorder and waits.

Price’s latest assignment has been to spy on the royal family—the feathered one in Caracas, Venezuela.

Price is a behavioral ecologist finishing up his doctoral degree at Carolina. For his dissertation, he spent the last five years spying on the stripe-backed wren—a small bird indigenous to South America—to see how these birds interact.

Unlike most birds in temperate climates, these birds tend to reside in one place (they don’t fly south each winter). They are called cooperative breeders because they live in groups and help each other out—kind of like a nuclear family. And because they are patrilineal—a group’s ancestry can be traced through the male line—they are like European royalty, whose male offspring wait around to inherit the top breeding position.

Each family of stripe-backed wrens consists of a principal male and female (mother and father)—generally the sole breeding pair—and then up to 12 offspring who all remain in the nest to help raise their brothers and sisters. “It’s kind of like in the U.S. when there’s a recession,” Price says. “The kids tend to stay at home with their parents longer.”

As the children get older, many of the females disperse or “marry” into other families. Often they have to compete with other females for vacant positions in families living nearby. The males, however, wait patiently to inherit the top breeding position at home. Price tracked one determined wren who waited around for 12 years (a long time in the life of a stripe-backed wren) to inherit the throne.

This type of bird behavior is very different from what we normally find in the U.S.“It’s not at all unusual here,” Price says, “for young birds to venture out on their own as soon as they are old enough to fly.”

Stripe-backed wrens are also monomorphic, meaning their sex cannot be determined by sight. To tell them apart, you have to listen to them speak.

That’s what Price has been doing for the last five years—spying on these birds and listening for distinctions in their vocalizations. He’s discovered that stripe-backed wrens have some fascinating family traditions that they pass on from one generation to the next.

It all started back in the 1970s when R. Haven Wiley, a renowned ornithologist and UNC-CH biology professor, started tracking the stripe-backed wren at Hato Masa-guaral—a 24-square-mile cattle ranch in the plains region south of Caracas, Venezuela. Wiley and a few of his students went to the ranch to study behavior in cooperatively breeding birds.

They began by gathering genealogies. First, they put colored bands around the birds’ legs to tell individuals apart. Then each year after that, they did a census and banded any immigrants and juveniles who had not previously been tagged.

In the late 1980s, one of Wiley’s former students, Kerry Rabenold—now a biology professor at Purdue University—performed DNA fingerprinting to confirm patterns of genealogical relationships.

While doing this research, Wiley noticed that the wrens had unusual-sounding calls. It sounded to him as if they were trying to say something. Wiley’s wife thought they sounded almost human, as if they were calling, Where are you? Where are you? So Wiley termed them WAY calls.

This was where Price came in. When he began his doctoral work at Carolina, he knew he wanted to study animals with complex social interactions, specifically communication within groups. So when Wiley mentioned this cooperatively breeding group of birds with interesting calls, Price jumped at the chance. He loaded up a backpack and headed south.

South to a very primitive area of land owned by Tomás Blohm, who has preserved his ranch as a wildlife sanctuary for researchers like Price so they can study animals in their natural habitats. Besides the stripe-backed wren, the ranch is home to over 300 species of birds. Other animals include the howler monkey and the wedge-capped Capuchin monkey, the rare Orinoco crocodile, cougars, rattlesnakes, and the capybara, a pig-sized rodent.

Price spent about nine weeks at a time on the ranch, and, at times, it was like a regular safari. While he was there, he lived in a small shack and slept in a hammock to avoid all the rats. He also had to endure South America’s rainy season, which arrives at the same time as breeding season for stripe-backed wrens.

Although much was known about this species’ breeding behavior, little was known about their communication. Price began simply by following these birds around with a microphone to record their sounds. This wasn’t always an easy task, considering the small size of the birds, which are only about five inches tall and weigh roughly one ounce. “And anybody who knows anything about wrens,” Price says, “knows that wrens are usually found close to the ground. But these wrens are unusual in that they stay way up in the canopy most of the time.”

Price had to be pretty resourceful to record their sounds. He and a few helpers used huge volleyball-type nets and stacked them on top of each other to raise the height. To catch the birds, the researchers set up the nets right next to the wrens’ nests, so that when the birds woke up in the morning they were all caught in the net together.

Females were even harder to record because they don’t tend to call as often—only at certain times, such as when they are leaving the nest to find a breeding position with another family. To record the females individually, Price had to net the entire group, release the females, and hold the males in a cloth bag. The released females would then call while searching for the males.

After recording and analyzing more than 10,000 wren calls, Price found that each male had a repertoire of between nine and 19 WAY calls, while each female had a repertoire of between three and five WAY calls. The female calls never matched the males’ in the same or even a nearby group, although their sounds aren’t really that different in acoustic structure. Both are composed of highly variable nasal sounds with some harsh, raspy elements, much like the vowels and consonants of human speech.

Since Price knew the genealogies, he was also able to make some interesting comparisons. In a few cases, he found two males living about a kilometer apart that had similar call repertoires. By looking back through the family records, he discovered that they were relatives, sharing the same paternal great-grandfather.

Another discovery Price made—the one researchers find most intriguing—is that sons apparently learn their calls from their fathers, and daughters learn their calls from their mothers. “There is definitely some type of selective learning going on,” Price says.

It’s not known for sure whether this selective learning is genetically predetermined. But what makes this interesting is that in most species of songbirds, the females don’t sing at all. Usually it’s the male songbirds who sing to attract the females. With other species, though, it’s probably easier for the males and females to tell each other apart by their coloring—as is the case with cardinals, where the male is bright red and the female a duller, almost brown color.

If the wrens can’t recognize each other by color, then they have to have some other way of determining who’s who. Price believes that birds are probably much more vocally oriented than humans are. He says, “Sometimes I would play back calls of neighboring birds that I had recorded in previous years, and they would recognize them, even after a year or two.”

What’s interesting about birds is that they actually learn their vocalizations,” Price says. “Take almost any other species of animals, excluding humans and whales, and you’ll find that most don’t learn their vocalizations. If you were to raise dogs and chickens in isolation with no other members of their species around, they would still bark or cluck.”

Besides humans, birds and whales might be the only other animals who learn their vocalizations. Price says that while many of the individual sounds songbirds produce are probably not learned, it does seem that these WAY calls are, as they occur in repertoires and are so complex.

And since their calls appear to be both sex-specific and family-specific, these differences may help them to avoid incest. In contests with neighboring groups over territorial boundaries, males might use their calls—similar to how Western society uses last names—to help distinguish one family from another. When females disperse from their nests and look for breeding positions in other families, they might be able to avoid mating or “marrying” with males related to their fathers.

While the stripe-backed wren probably provides the first case in which individuals of each sex have been shown to have a preference for learning their vocalizations from relatives of the same sex, Price points out that most studies of songbirds have been conducted only in temperate regions. “It will be interesting to see what future studies of other highly social animals will reveal,” he says.

Not only does Price’s discovery help prove that there are other species out there who have complex social relationships, but it also shows that long-term studies can be beneficial. Most funding agencies, for example, prefer to fund short-term studies with quick results. “But that’s not always the way it works,” Price says. “Like with this study, I wouldn’t have gotten the results I did without the previous studies. It takes a long time and a lot of animals.”

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

Staking out Carolina’s natural classroom

You don’t have to go as far as South America to study wildlife up close. Just a few miles down the road, Chapel Hill has its own wildlife sanctuary. Part of the North Carolina Botanical Garden (NCBG), the Mason Farm Biological Reserve is a 367-acre tract of land that serves as both a biological field station and natural classroom.

Since 1984 when the reserve was officially established, dozens of researchers have used the land to conduct various research projects. Jeremy Hyman, a biology doctoral student, uses the reserve to study territorial communication of the Carolina wren. Hyman says the reserve is a great place to study birds because there are two large forest plots that have been staked out, making it easier to define territories: “Instead of trying to remember where a bird was singing by referring to a specific tree, I can simply look at the plot and mark the spot on my corresponding map.”

Other research-support areas include nursery space, plant propagation beds, an animal behavior research station, and green-houses. Johnny Randall, conservation curator at the NCBG, says a lot of faculty members bring their classes for field trips. He says, “It’s got all of the necessary components of a functioning ecosystem, so it’s a great place to study both plants and animals.”

The Department of Biology has many projects going on here, Randall says, but so do other departments. Anthropology classes use the reserve to study how Native Americans may have made use of the land, and photography classes can find many willing subjects in their natural habitats.

The reserve is part of the Mason Farm area that was willed to the University in 1894 by Mary Morgan Mason, widow of the Reverend James Mason. Both of Mrs. Mason’s daughters died of typhoid fever in 1881. With no heirs left, she decided to leave the land to help support the University.

Catherine House was formerly a staff contributor for Endeavors.

A free permit to visit the reserve is available from the North Carolina Botanical Garden.