Photo by Aspen Stevanovski
Red Wolves Canis rufus
Howard McCarley and the Lost Recording from 1973
On a chilly autumn day just outside Yellowstone National Park, I checked my phone and saw an email from Murray McCarley, whom I did not know. He was reaching out to thank the Cry Wolf bioacoustics project for its study of gray wolf communication (Canis lupus), recently featured in the Washington Post. But what truly caught my attention was mention of a long-lost audio recording from the early 1970s—his father’s reel-to-reel tape of a red wolf, captured with equipment vastly different from the modern technology I’m fortunate to use today.
The red wolf (Canis rufus) is a critically endangered canid of the southeastern United States, recognized for its reddish fur and lean build, placing it between the gray wolf and coyote in size. Historically, red wolves roamed forests, swamps, and coastal prairies, but due to habitat loss, hunting, and hybridization with coyotes, their numbers dwindled. By the 1980s, they neared extinction in the wild, leading to a reintroduction program in North Carolina’s Alligator River Wildlife Refuge, where fewer than 20-30 wild individuals now remain. Mike Philipps, whom I had come to know due to his role in Yellowstone National Park's wolf reintroduction, was instrumental in the red wolf recovery program. As social animals, red wolves live in family packs and primarily hunt deer, raccoons, and small mammals, playing a role that all predators do in the food web. Hybridization with coyotes and human-wildlife conflicts challenge their conservation. Conservationists, and those who appreciate wildness, face a steep uphill battle to protect this unique species through habitat preservation, genetic monitoring, and public engagement.
In 1962, an Austin College professor named Howard McCarley in Sherman, Texas sounded the alarm about the red wolf and its unexpected spiral toward extinction. He pointed out that what people thought were wolves were actually coyotes or wolf-coyote hybrids. The wolf’s howl helped reveal the dire situation.
In the 1960s Howard looked for skulls in order to detect red wolf presence. In the mid-70s he got the idea to start looking for them via their howls and Murray, a teen at the time, would go along for many of the rides. They drove back roads at night playing taped wolf howls and used an old, motorized fire department siren mounted on plywood and run off a car battery—a sound the wolves can’t resist answering—and listened for a response. The choruses of answering howls came from both wolves and coyotes, and they focused in on the howls that were distinctly wolfish. Howard would train many of his students to use this technique, who went on to use it in their own careers.
Howard's Tapes and Notes
The red wolf no longer roamed its familiar territory. The biologists determined that the only red wolves remaining were hemmed in along a stretch of coast in southeastern Texas and southwestern Louisiana. It seemed to be an unlikely final redoubt for the forest-loving wolf — coastal prairies and marshes that are a stone’s throw from Houston, Galveston and Beaumont, in the shadow of one of the most industrialized areas of the country, an area of rice farms, cattle ranches and oilfields.
They ultimately found at least 100 wolves, mainly in Jefferson, Chambers and Liberty counties. And one day, they recorded red wolves in Chambers county, using an UHER 4000 Report-L recorder with a microphone mounted in a hand-made parabolic dish. Murray sent me the reel-to-reel tape, but I still had to find and rebuild an old portable UHER 4000 Report-L, the kind that news reporters used to carry around with a strap over their shoulder. Finally, with duct tape and a soldering iron, Howard's recording was playing and ultimately converted to this digital version.
Red Wolf versus Gray Wolf Howl
Gray wolves and red wolves differ significantly in size, with gray wolves being the larger of the two. On average, gray wolves (Canis lupus) weigh between 70 and 150 pounds (32–68 kg) and stand about 26 to 32 inches (66–81 cm) at the shoulder, whereas red wolves (Canis rufus) typically weigh between 45 and 80 pounds (20–36 kg) and stand around 24 to 26 inches (61–66 cm) tall. This makes gray wolves approximately 30–50% larger than red wolves in terms of both weight and stature. Skull length also varies, with gray wolves averaging 9.1 to 11 inches (23–28 cm) compared to the shorter red wolf skull, which ranges around 8 to 9 inches (20–23 cm). These differences reflect each species' adaptation to distinct habitats and prey, with gray wolves suited to larger prey in open terrain, while red wolves are adapted for smaller prey in dense, forested environments.
These size differences are likely the reason a gray wolf's howl is lower in pitch (on average, 350 hertz in Yellowstone) than a red wolf's (on average, around 600 hertz, more like a coyote's). You can see and hear the differences by watching the video below. A spectrogram is simply a way of visualizing the pitch, duration and loudness of a sound. Lower pitches are down lower on the Y axis.
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Rebuilt UHER 4000 Report L (1965), Gray & Red Wolf Skulls
Technology: Then
Back in Howard’s day, recording animals—or people, for that matter—meant lugging around a reel-to-reel cassette recorder that was roughly six times the size of today’s devices, weighed a ton, and was about as user-friendly as a lawnmower. To capture a wolf howl, you’d need a parabolic microphone the size of a satellite dish, a few unwieldy magnetic tape reels, and enough batteries to power a small town. Ok, that's a little over the top, but you get the point. Then, to actually analyze the recordings, you'd haul out yet another machine to print spectrograms (or sonagrams) on paper. And no, nobody had one of these in their living room like a laptop. This was industrial-strength audio gear, not exactly something you’d pop open over breakfast.
Kay Electric, founded in 1947 by Elmo "Bud" Crump, developed the first commercial sound spectrograph, known as the Sona-Graph (device in top right). The technology became a critical tool in the analysis of speech, animal vocalizations, and signals intelligence and the technology is now owned by PENTAX Medical.
Murray Holding Parabolic Mic
UHER Microphone
Sonogram of Red Wolf Howl on Paper
Technology: Now
Nowadays, we use digital acoustic recording units (ARUs). They can be programmed to record all of the time or at specific times of the day. Battery life ranges from 2 weeks to forever (on solar panels) and storage is on a hard drive the size of a thumbnail. And we can store all of that data on multi-terrabyte drives that only cost $400 and fit in the palm of my hand. It would take an Olympic-sized swimming pool to hold all of the tapes Howard used in order to store that much data. Perhaps more significantly, we can analyze the data with computers and monitors that allow us to look at an hour of audio at a time and step through 100's of hours in minutes. And now, Artificial Intelligence helps us find what we are looking for, such as wolf howls or the song of a black-capped chickadee.
The times have changed, but the gratitude we all owe to people like Howard McCarley hopefully goes without saying. Thank you, Murray, for helping me tell a small part of your dad's story...and yours. I agree, Howard, "there will probably never be a last lecture on wolves because new information keeps coming in and changing our interpretations."
Modern Audio Recording and Analysis Technology
A Recent Success
In spite of the daunting challenges faced by red wolves, a recent success is worth noting. The following press release from Wolf Haven International provides some hope.
In October 2023, critically endangered American Red wolf, M2191, was transported from Wolf Haven International to the Alligator River National Wildlife Refuge in eastern North Carolina. M2191 was placed in an acclimation pen in the local territory of the Milltail pack in the hopes that he would be accepted into their family group. After three months of positive interactions with the pack through the acclimation pen fence, M2191 was released and took his first steps into the wild on January 26, 2024.
Shortly after his release, M2191 was seen traveling with the pack’s breeding female, F2225, on remote camera. He integrated well with her four two-year-old’s and four yearlings, and in mid-April, the United States Fish and Wildlife Service (USFWS) confirmed that F2225 and M2191 produced their own litter of eight pups!
Wolf Haven, an internationally recognized wolf sanctuary and education center in Tenino, Washington, has participated in the American Red Wolf SAFE program since 2003 and the Mexican Wolf SAFE program since 1994 (formerly Species Survival Plan/SSP programs). Wolf Haven follows strict guidelines when caring for SAFE animals – interactions with humans are kept to a minimum and observations are done by remote camera.
M2191 (house-named Finch while in captivity) was born at Wolf Haven in 2016, and for more than seven years, Wolf Haven’s animal care team worked diligently to ensure he remained as wild as possible while also preparing him for the possibility of release into the wild. At the annual SAFE meeting in July 2023, M2191 was recommended for release and Wolf Haven’s Lead Animal Care Specialist, Judah Jamison, quickly began working with program leaders to develop a plan to relocate him from Washington to the recovery area in North Carolina. “It is an incredible honor to be part of the SAFE program and the American Red wolf recovery effort” says Jamison. “Knowing that a wolf who lived seven years at Wolf Haven has integrated into a wild pack is overwhelmingly joyful and humbling.” M2191 is the second American Red wolf from Wolf Haven to be released into the wild in North Carolina, following the release of
F2216 (house-named Iris) in 2021. In addition to these pivotal releases, five litters of American Red wolves have been born at Wolf Haven in the past 20 years. Sanctuary Director Pamela Maciel Cabañas, who has been with the organization for over ten years, is continually inspired by the work Wolf Haven is doing to conserve and protect wolves. “To have any of these pups not only get a chance to live their full potential in their natural habitat, but to also potentially contribute to the growth and genetic diversity of the wild population by producing pups of their own, brings the work we do full circle.” For more information about Wolf Haven International’s American Red wolf and Mexican wolf conservation efforts, please visit wolfhaven.org/conservation/SAFE. Updates from USFWS on the wild American Red wolf population can be found at fws.gov/project/red-wolf-recovery-program.
Source Documents
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A Report to the National Geographic Society and The World Wildlife Fund: Vocalization Patterns in Wild Red Wolves and Coyotes (Howard McCarley, December 14, 1974)
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The Taxonomic Status of Wild Canis (Canidae) in the South Central United States (Howard McCarley, December 10, 1962)
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Recent Changes in Distribution and Status of Wild Red Wolves (Howard McCarley, September 18, 1978)
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Long-Distance Vocalizations of Coyotes (Howard McCarley)
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The Red Wolf (Canis rufus) Recovery Program: Things They Didn't Tell me in School (Curtis J. Carley)
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The Red Wolf Re-Discovered (Texas Wildlife Association, 2021)
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Last Stand of the Red Wolf (Russell Roe, 2012)
Howard's Tongue-in-Cheek "Last Lecture" on Wolves