Comparing Purported Bigfoot Vocalizations with both Non-human and Human primates.

Author Randy "Rebelistic" Savig, Missouri State Director, MABRC



Over the years of researching the elusive primate that we have come to call Bigfoot, there seems to be some consistently purported vocalizations in areas of activity.  Even though I suspect that that Bigfoot uses a much wider variety of vocalization, some of which it has probably never been recorded, the most common seem to be the long howls(calls), the whoop, knocks, and screams.  Others that have been reported are grunts, whistles, roars, as well as woohoo.

As we know all primates also use gestural communication also.  The most common of these is rock or stick throwing, thumping and stomping, branch breaking, and bluff charges.  One other thing that seems to be significant with researchers is the feeling of being watched. If you have ever been someplace and got the feeling you were stared at and looked around and found someone doing it you can understand this feeling.  It happen a lot with people.  Other primates such as a gorilla it seems to be for a fairly specific reason.


staring: This where the sender has its eyes fixed on the receiver, the eyebrows are lowered, the head is angled down, and the lips are parted and pursed (Estes, 1991). This communicates aggression or annoyance (Estes, 1991).


We all got that look from our parents and grandparents so we all know what this one means!


With the modern-day advances of the Internet, researching sounds and animals has become easier.  Facebook and YouTube has in a lot of ways made Bigfoot research even harder with all the hoaxing that goes on with YouTube videos, as well as all the fringe groups with their cult-like followings.  However, you can use both as a positive thing.  When looking up primate vocalizations YouTube is full of them.  In doing so it is easy to copy the file and put it on a spectrogram compared to the purported Bigfoot vocalizations.  Facebook is not a great place where you can compare vocalizations with other researchers as very few do the background work and think everything is bigfoot.  I have heard so many normal animal vocals like owls, foxes, even squirrels being said is bigfoot.  But if a person is diligent you can find good folks who are willing to share and compare.    


In doing this paper I find it much easier to post a video with primate vocalizations than it is to try to describe.  The YouTube videos that I am using here are for comparison and educational use only.  And by no means am I claiming ownership of the majority of them.  However I have done what I can to insure that what I have used is authentic to the primate being represented.  I have done a lot of reading of information available on the Internet and come up with this hypothesis.  A list of referenced material are shown at the bottom of the page.  But as a disclaimer goes, this is my opinion based on extensive fieldwork, hundreds and hundreds of hours of audio review, and talking with other researchers about the suspected Bigfoot vocalizations.  I would really like to see other researchers use some of this in their research areas to either help confirm that it is a correct hypothesis or a false one.


It seems like a lot of times in Bigfoot research.  We hit a spot where what we used to do just does not seem to be working anymore or were not getting the answers to the questions our research is brought about.  I have put a lot of time in thought into this project and I am hoping with using this as a template that may be some more interactions can be made and knowledge increased.  All the skeptics out there will look at this and say that it is a bunch of BS because Bigfoot is not been proven to exist.  However, with all the researchers that have had sightings and other interactions know that they exist.  This entire paper is been written from a researchers point of view.


When looking at the vocalizations and gestural communication of the known primates, there seems to be a pattern of the use of certain vocalization that all primates use.  I believe that if we use what is known in the primates, it could help in deciphering what the purported bigfoot vocalizations may mean, as well as how we can use them in the woods while researching these animals.  By no means am I saying that this is the only possibility for the purported bigfoot vocalizations.  Until such time where they can be monitored by science to where the vocals are seen in context we will not know.    


 Historically, the common view of animal communication was that each vocal utterance corresponded to a particular emotion; screams for fear, barks for aggression, and coos for comfort (Smith, 1977; reviewed in Cheney & Seyfarth, 1990a; Hauser, 1996)


There is an ongoing debate about whether and to what extent nonhuman primate vocalizations are intentional, voluntarily controlled communicative means (TomaselloandZuberbu¨hler 2002). Although vocalizations seem to be largely innate, with a limited number of vocalizations in an individual’s repertoire, there is flexibility in regard to the usage and comprehension of vocalizations, with some species even comprehending the calls of other species, which requires learning (Zuberbu¨hler 2000a). In addition, there is some variation in certain calls as a function of population-specific dialects (Mitani, Hunley, and Murdoch 1999) or affiliation to a particular matriline (Hauser 1992)


There the specific vocals seen by scientists in context are talked about.  When we compare that to the purported Bigfoot vocals, it may be useful in the woods while researching.  Here is a good site for comparing a lot of non-primate vocals.

The long call.

The long call in primate research doesn't just mean the length of the call but more with the distance that it can be heard.  Most of these are used to as a way to joining back up the troop for food or as a possible mating call.  This is even true for humans.  Years back before texting and cell phones your parents would stand on the porch and yell for the kids and family at dinner time.  Even though we couldn't hear the actual words we knew the call.  Even in areas where there were kids from different families everyone knew who's mom was calling.  

In Chimps:  pant-hoot: This is consists of a series of loud calls which are rising and falling in pitch and often end in a scream (Nishida and Hiraiwa-Hasegawa, 1987). This call is most often given by males, but females may also give it (Nishida and Hiraiwa-Hasegawa, 1987). This call is given at abundant feeding sites, after smaller groups have been reunited after a few days, a response to loud calls, and as a response to charging display (Nishida and Hiraiwa-Hasegawa, 1987).

In chimpanzees, the production of vocalizations varies with rank and social context: at Kibale,
high-ranking males call in all social contexts, whereas low-ranking males and females only call in mixed parties (Clark, 1993). At Gombe, all rank and sex classes also call in mixed parties at the provisioning site (Clark, 1993; Marler & Tenaza, 1977). Call production in chimpanzees also varies with ecological context. Captive studies show that production of loud calls (pant-hoots) in feeding contexts differed by the quantity and divisibility of the provisioned food (Hauser et al., 1993). Earlier work on wild chimpanzees at Gombe and Kibale (Ghiglieri, 1984; Wrangham, 1977) suggested that loud calls (arrival pant-hoots, APH) given upon arrival in food patches by male chimpanzees function to attract allies, mates, or both to abundant food sources.

In Orangutans:  loud call: This call is given by the adult male and consists of roars at first and then rises to bellows and is enhanced by the throat sac. This is used to demarcate territories and to attract a mate, and is important because the orang-utan lives in such dense forests that it is difficult to see other individuals.

( Parental Notice:  This one was only selected for the long call and does show mating so it should be watched by adults only)


Bonobo vocalizations have been studied in captivity (van Krunkelsven et al., 1996; deWaal, 1988) and the wild (Bermejo & Omedes, 1999; Hohmann & Fruth, 1994; Mori, 1983). It has been suggested that the long range vocalizations of this species, such as the high-hoot, are structurally better for localization of the source than for carrying over distances greater than 500 m (Hohmann & Fruth, 1994; deWaal, 1988). Male and female calls differ in pitch (Hohmann & Fruth, 1994). Krunkelsven et al. (1996) found that production of soft, “food peep” vocalizations was related to both social context and food quantity, but did not find sex differences in calling behavior in either context. De Waal (1988) described more than a dozen distinct types of loud and soft calls used by bonobos in captivity. During his study, most loud calls were used in exchanges between parties out of visual contact rather than being directed at individual conspecifics. Loud calls were also given during party movement and were associated with feeding (de Waal, 1988).  More recent captive studies have shown that bonobos change their foraging behavior in response to food-associated calls from others (Clay & Zuberbühler, 2009, 2011). Wild studies have found that bonobo loud calls vary through the day and were most frequent in late morning and late afternoon. The later peak was associated with travel to and construction of night nests. Observed parties’ most common response to calls of distant parties was to vocalize and/or travel (Hohmann & Fruth, 1994)

Using this information I think it is reasonable to suspect that vocals like the Missouri Scream and others have the same function. If one is to use call blasting as a way of trying to draw in possible bigfoot from a distance, this is one that I suspect will work.  

The biggest drawback for using call blasting is that with the equipment most researcher can afford can not get an adequate volume or sound quality of the original call.  However it is worth a try and there are those who have had success.  Just try and keep the volume mid-level to keep the mechanical sound to a minimum.
Here is some of the vocals purported to be bigfoot.  It seems to pretty much cover all the categories I've covered here.

Video no longer available

Whoops, and other short abrupt calls.

One calls that Bigfoot is purported make is the Whoop.  In primates it would appear that these loud sharp and short vocals are used as an alert or mild aggression. From my personal experience while researching it does seem to be a alert call.  When we spotted what we took to be a juvenile and was mimicking what it was doing there was the vocals about 30* to our left that seemed to warn the juvenile that we had seen it.


Here is a compilation of some of the whoops I have recorded.

An example of the ways in which a communication system is not arbitrary is that across all known animals that make noise, a quick, high, sharp sound means danger. Conversely, a low, sustained sound is reassuring.

Wilson, Hauser, and Wrangham (2001) showed that, in response to the playback of the pant-hoot call of a single extragroup male, parties with three or more males consistently joined in a chorus of pant-hoots and approached the loudspeaker together, while parties with fewer adult males usually stayed silent and approached the loudspeaker less often.

In gorillas
wraaa: This call is given as a fear vocalization especially the fear of something strange (Estes, 1991).

wraagh: This call is also an outburst, but not deep as the roar, and is monosyllabic in nature (Estes, 1991). This call is mostly emitted by the silver-back male (Estes, 1991). This is emitted when the individual is experiencing sudden stress, and group members scatter when hearing this call (Estes, 1991).

pig grunts: This call consists of a series of short guttural noises (Estes, 1991). This call is given by adult males and females, and communicates mild aggression (Estes, 1991). This call is emitted when the adult wants access to preferred foods or right of way (Estes, 1991).

question bark: This call consists of a short series of three notes, the first and third being lower in pitch than the second (Estes, 1991). Mostly this is given by the silver-back male, and he emits this when he discovers someone that was concealed or another individual that is making noise but can not be seen (Estes, 1991).

chimpanzee -- Pan troglodytes

Tanzania, Kigoma  ML 196297 © 2016 Cornell University (In the middle of the vocal sounds a lot like a whoop.)  

It would seem as if using whoops or other short abrupt call may not be of benefit to have Bigfoot approach.  With that in mind I would like to have others help to test this hypothesis.  I know it is hard for any of us to imagine that a researcher would want to take the chance of stopping an experience that may be bigfoot related, but if a person is getting spooked I would like them to try it to see what response they get before using white light.  Until more data is compiled I wouldn't suggest using this as a way of drawing them in.  

Even though screams are a long distant call it appears to a single focus for primates.  

Gorillas scream: This call is loud and is a shrill sound repeated many times (Estes, 1991). This call is emitted by all gorillas, and is given when the individual is upset or fighting with other gorillas (Estes, 1991).

This video is covers pretty much all the known vocals of the Gorilla.

Chimpanzee screams

I highly suspect this to be true with the purported bigfoot screams to.  This has been reported in sightings reports and may also be the "Woman being murdered" vocal that we hear reported.  I have recorded screams in the woods that I have suspected to be related to bigfoot.  There was one time in particular where they seemed to respond to our granddaughters screams.  It even did appear as if whatever was screaming was moving closer.  However there were no possible sightings or suspected close activity so I'm not sure what was going on.  

This next one was recorded at an active research site in Oklahoma.

We do know that in human a scream is usually done when we are startled or scared.  Could on going screams mean that there is something to fear in the woods? In call blasting or mimicking this could be a way of drawing them in.  The researcher should be ready in case this is a scared or threatened bigfoot vocalization.  It could take make for a negative experience. 

GruntsKnocks, Woohoo,(Woo) and Whistles

There is a unique way that primates keep track of one and another in the forests. Some of the ways are listed below.  I suspect the purported bigfoot knocks and other vocals are used for this purpose.  With the Silent Hill Project showing that knocks do NOT carry long distances, it can be assumed that it is a location type of call.  Each primate has a way of determining parent and offspring vocals through various vocalizations.  Although the differences may be subtle and only seen on the spectrogram each is individual.

Japanese Macaque coos

The coo is a common short-range vocalization between group members. It didn't seem to be restricted to any particular situation, but was just a noise that they made sometimes. He looked at spectrograms of the coos, divided them into different types, and realized that certain types happened during certain circumstances. This suggested that primate repertoires might be bigger than we had thought- and also that their calls were more context-specific than we had thought, which raised possibility that they might also be more representational than we had thought.

Here is what I suspect is the calls of the Woo, Woohoo vocals reported with possible Bigfoot activity.  These are some of what I have recorded during my research.


Knocks are the one of the most common sounds associated with suspected Bigfoot activity.  Even though we do not know the exact mechanism used, whether the wood on wood, rock on wood, or even could be a hand clap, chest beat.  The mechanism used is not known as it has not been observed. Recently we have started to respond when we hear what we suspect is knocks. 
Here is a few times where we did have success to that. 


Here is a real odd one.  A two tone double knock.

Even though we have had some success at getting responses to knocks, we always mimicked them and did not start the knocking sessions.  Again, these are not long distance sounds.  So if you are in the woods and hear one, I would suggest trying to reply.  It may extend the experience. 

This is one of the vocals that is reported and in my opinion is the least understood. As shown above gorillas can make a pig grunt type of vocal. 

pig grunts: This call consists of a series of short guttural noises (Estes, 1991). This call is given by adult males and females, and communicates mild aggression (Estes, 1991). This call is emitted when the adult wants access to preferred foods or right of way (Estes, 1991).

However the belch vocal that gorillas also use is a sign of contentment.

belch vocalizations: This call is given by all gorillas, generally when they are stationary, and generally communicates contentment (Estes, 1991). These noises consist of purring, humming, rumbling, crooning, moaning, and soft-grunting noises (Estes, 1991).


Table 1.
Overview of close call types and their contexts described for mountain gorillas (MG) and
western gorillas (WG).
Call type Species Context
Syllabled calls Grooming, in response to noise, by mothers to
infants, towards the end of resting periods
(Harcourt & Stewart, 1986; Harcourt et al., 1993;
Stewart & Harcourt, 1994)
Single grunt MG/WG Feeding, resting, travelling (Salmi et al., 2013)
Double grunt MG/WG Individually distinct (Seyfarth et al., 1994);
feeding, resting, travelling (Salmi et al., 2013)
2 subtypes MG Spontaneous and reply call (Seyfarth et al., 1994)
Triple grunt MG Unknown
Inverted grunt MG Unknown
Train grunt/whinny∗ MG/WG Mating (Harcourt et al., 1993; Salmi et al., 2013;
Watts et al., 1991; Sicotte, 1994)
Non-syllabled calls As chorus when individuals are feeding and
moving close together (Harcourt et al., 1993)
Grumble MG/WG More by low ranking as compared to high ranking
individuals (Harcourt et al., 1993); feeding, resting,
travelling (Salmi et al., 2013)
Hum MG/WG Mainly feeding, rarely resting and travelling (Salmi
et al., 2013)
High hum/sing MG/WG Feeding (Salmi et al., 2013)

Dog whine MG Unknown


In Chimps


pant-grunt: This consists of a series of soft, low grunts (Nishida and Hiraiwa-Hasegawa, 1987). This is given by subordinate individuals to dominate ones as a response to dominance displays, such as the charging display (Nishida and Hiraiwa-Hasegawa, 1987).

Here is where you can compare a lot of gorilla vocals with.  By listening to this the above vocals will make more sense.

Here is a site with some of the best Chimpanzee vocals I have been able to find for comparison purposes.  Do to high number of vocals that chimps do for the range of reasons there is a lot of stuff here.

Some of the grunts that are reported as possible bigfoot may have the same purpose as some of the grunts we hear could be like the Belch Vocals of the Gorillas and the pant-grunt in the Chimps, a relaxed vocal.  However some of the grunts seem aggressive like the Pig Grunt in Gorillas.  I do think that a seasoned researchers should try to mimic these types of vocalizations to see how they are responded to.  If they are a non threatening vocal it may help to extend the encounter and possibly add to it.  Until this type of vocal is studied more I would not suggest to be alone if you do it. 

Aggressive vocals, Roars, Charge Displays
Roars are I believe with every animal as sign of aggression.  Here is one of a gorilla roar.  Notice the way it charges the people behind the glass.  Because of the glass and it knowing it is there it is really unknown if this was a bluff charge or would have been a real one.  

Here is some of the possible roars that I have recorded over the years.  Even though I can not say definitely they are from a bigfoot they don't seem to match with the known animals in my area.  With primates known to use roars when aggravated it is not out of the realm to think that a bigfoot wouldn't.  Here is some of what I think are roars from my research area.

chest-beating: This behavior is done by all gorillas and the either one or two open-fist hands are clapped against the chest (Estes, 1991). Adult males produce a sound when doing this because of air sacs they have which are located on both sides of their throat (Estes, 1991). For the adult male this is a threat display (Estes, 1991).


In Chimps 
charging display: This is where an individual is running and/or throwing objects such as branches or stones and/or pant-hooting, drumming, slapping, stamping, and screaming (Estes, 1991). This display is performed by adult males and occurs when a dominant meets another individual after a long time or done by the alpha male to keep all others subordinate to him (Estes, 1991). This display also occurs by an adult male when there is a heavy rainstorm (Estes, 1991).


This type of thing may account for the for some of the broken branches and trees that some have attributed to bigfoot.  When other primates use these things to display dominance or as a way to show off to a possible mate it would not be a huge leap to suspect bigfoot could also do displays like this.  

We all know this happens in humans too.  All the behaviors we see such a bullying, trying to gain attention from the opposite sex, even the favorite line of "watch this" in childhood and adulthood is to try and show worthiness.  

Here is an audio clip that was recorded of what I suspect is bigfoot.  It shows all the characteristics of aggressive sounds that is used by primates.  It is unknown of why the vocals were made as it was recorded with a recorder left on the truck during a day hike.

(This is a long vocal event and has not been altered in time or quality)

(This is a shorten clip with comparisons to a gorilla and some of the audio cleaned up for better clarity)

And it is not a one time event.


This type of thing is also somewhat in the grunt category so as I said above using any type of grunt is a risk.  Only researchers that are ready for the possible results should attempt to use it either as a mimic, or in call blasting in the field. 


One other thing that is reported with bigfoot is smell.

There are numerous reports of a smell associated with Bigfoot.  Some primates have a smell at times.  If this holds true with bigfoot as it does in other primates it could also explain why it is not reported every time.  People also have more odor produced if they are nervous or excited.  

In Gorillas

fear smell: This is produced by the silver-back male, and comes from glands under his armpits (Estes, 1991). This signals excitement or an aggressive threat (Estes, 1991).

Information of the Author

Randy "Rebelistic" Savig
Missouri State Director for the MABRC
Investigator/Researcher for the MABRC
Member of the MABRC Evidence Review Board

(This is the link to my research thread on the MABRC forums)

(This is my personal YouTube channel as has the audio that I have collected over the years of possible bigfoot sounds.) 


Acoustic structure and variation in mountain and
western gorilla close calls: a syntactic approach

Daniela Hedwig a,∗, Kurt Hammerschmidt b, Roger Mundry a,
Martha M. Robbins a and Christophe Boesch a
a Max Planck Institute for Evolutionary Anthropology, Department of Primatology,
Deutscher Platz 6, 04103 Leipzig, Germany
b German Primate Centre, Cognitive Ethology Lab, Kellerweg 4, 37077 Göttingen, Germany
*Corresponding author’s e-mail address: This email address is being protected from spambots. You need JavaScript enabled to view it.
Accepted 10 January 2014; published online 14 February 2014

Western Gorilla Vocal Repertoire and Contextual Use of

Roberta Salmi*, Kurt Hammerschmidt† & Diane M. Doran-Sheehy‡
* Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University, Stony Brook, NY, USA
† Cognitive Ethology Laboratory, German Primate Center, G€ottingen, Germany
‡ Department of Anthropology, Stony Brook University, Stony Brook, NY, USA