As part of our conservation efforts, The Cry Wolf Project aims to provide third-party verified data to help prevent wildlife-livestock conflicts. The USDA has already done studies showing some efficacy in deterrence by playing human sounds (on drones) and using flashing lights (on ear tags).
Grizzly Systems has partnered with Kurt Holtzen, a wolf conflict mitigation expert and fifth-generation agricultural producer. GrizCam’s founders, CTO Cody Goldhahn (also a rancher) and Dr. Jeff Reed (bioacoustics researcher), are developing the next generation of what are called rag boxes. Rag boxes are simple devices that play sounds through speakers to deter wolves or other predators from livestock.
Rock music and firecrackers are commonly played to make wolves leery of human presence. But what do wolves actually think about the sounds we’re playing? Are we speaking their language? Based on over 7,000 audio recordings of wild wolves, Jeff created the following suggestions for selecting the best vocalizations to deter wolves. The sounds are free to download and use with rag boxes; please credit Jeffrey T Reed / The Cry Wolf Project. All recordings are by Jeffrey Reed.
Human sounds
The leading cause of death for wolves outside of protected areas (like Yellowstone National Park) is human activity. Consequently, wolves tend to alter their behavior around people, yet they remain cautious of rival wolf packs as well, steering clear of both. Playing human-related sounds during the day (and occasionally at night) along with wolf pack chorus howls at dusk, night, or dawn is a realistic approach to what an intruding wolf would know is “not safe.”
Wolves and their descendants, dogs, use specific barks to signal different threats. Playing a wolf’s human-directed bark, growl-howl or bark-howl might make an intruding wolf think another wolf is warning of nearby humans. For more realism, I will also play a gunshot or a large vehicle driving down a road, followed by a wolf’s bark-howl or growl-howl. Similarly, multiple guardian dog barks (especially the type they direct at predator threats like us, wolves and bears) could suggest to a nearby wolf that other wolves, and potential risks, are present in the area. The key, however, is that the intruding wolf needs to be fooled into thinking that other unfamiliar wolves are present, not just itself. Playing a chorus howl with the guardian dog barks is the common-sense approach to deterrence.
Wolves vocalize in frequencies similar to human speech, making them attuned to our voices. Playing music with lyrics can be effective, but an even more realistic option is to play recordings of three or more people talking, with the volume turned up to 100 decibels. To enhance realism, try playing sounds of a truck approaching, slowing down, stopping, and car doors closing, followed by voices. After a 1–2 minute pause, play a wolf’s growl-howl or bark-howl.
Wildlife management agencies often use helicopters to capture or remove wolves. Wolves with frequent exposure to this tend to run at the sound of an approaching helicopter, while they seem indifferent to the noise of small planes. Although I haven’t tested it yet, occasionally playing helicopter sounds during the day might be effective. Further observation is needed to explore this idea, but I’ve included audio for those who want to experiment.
Chorus howls
Wolves cornering a wolf from a rival pack.
Wolves communicate with over 20 distinct sounds, including barks, yelps, whimpers, moans, and teeth clacking, alongside their iconic howls. But one of the most effective sounds for a rag box is the chorus howl.
Wolves are one of a few species that communicate collectively, and they do it with chorus howls, which typically contain three different call types (howls, yip-yaps and woas). Chorus howls last about two minutes, and wolves can identify the pack and relative size of a chorus howl from its unique vocal signature. Playing an unfamiliar chorus howl from a large pack signals to other wolves the presence of potential danger and competition. In encounters with rival packs, wolves often resort to extended, repeated chorus howling over hours, a safer strategy than risking deadly conflict. Coyotes frequently respond to wolf chorus howls with their own, so playing both together adds realism to the soundscape. I do not recommend playing solo wolf howls, except for the growl-howls described below.
Rival wolves
The number one cause of death for wolves in Yellowstone National Park (and other protected areas) is other wolves. Wolves, especially solo wolves or small groups, will typically avoid wolves that are not part of their social group. Combine the following calls with the human-generated sounds above.
Time of day
Wolves primarily howl and chorus howl at night, with peak activity between 11 p.m. and 3 a.m., often extending through dawn as they prepare to hunt. They do chorus howl at dusk, but less often than at other times, so replicating the nighttime pattern mimics their natural behavior most effectively.
Wolves increase their daytime howling mainly during the breeding season, typically from January through March, often as a means to attract mates. For deterrence, however, daytime is generally not a good time to play howls on a rag box: it may have unintended effects, potentially drawing wolves in rather than keeping them away.
Distance
Chorus and individual wolf howls can carry up to 3 miles or more, depending on conditions. Wolves likely favor night and dawn howling, when atmospheric inversions and low winds enhance sound travel. At 100 decibels, a typical wolf howl is as loud as a car horn heard 10 feet away. To cover larger areas effectively, place speakers with a 100+ decibel output about 6 miles apart for maximum reach when playing these recordings.
Growl-howls
Evidence suggests that longer-duration howls are often directed at non-packmates. While I don’t recommend playing regular howls to deter wolves, a specific version called a growl-howl, typically directed at rival wolves or humans, may be more effective. Mixing long-duration growl-howls with various chorus howls can be a reasonable tactic for deterring wolves.