How a gobbler drums

[Ranger]

Good discussion here

[Treerooster]

I say it's air being pushed out his Kraw area causing vibration .

Bingo.

The drum comes from the crop that has been inflated with air. The gobble comes from his lungs. That is how he can do both at once. Just theory on my part, but that's what I believe is going on.

Turkeys are galliformes (chicken like birds). When you think of other galliformes like sage grouse, sharptails, prairie chickens, blue grouse, etc...these birds have air sacs they use to attract mates. Why not a turkey using an air sac? But the turkey is a large bird and still needs to fly. So they could have evolved so their crop doubles as the air sac saving weight for flying. Just another theory of mine.

[falltoms]

I don't know how it's done, if it came from the air in the crop, then they could only do it when it's completely empty, which first thing in the morning it usually is. I know gobblers don't eat much during breeding season, but they do eat some, it may come from the crop, but if there's any food in it, I don't know how that would work.
I think its a mystery, no one had figured out, and it should stay that way

[Ctrize]

I know when I try to mimic the sound it is easier to do the spit on the exhale, cut it off then vibrate my body to create the vibrating. I have seen featherless domestic turkeys strut and their remaining tail feathers are definitely shaking or vibrating. Perhaps the vibrating is an extension of the energy used when exhaling to drum. The sound has a tailing-off sound as if running out of air.

[HookedonHooks]

The spit is very much vocalized, but the drumming is certainly an internal sound. Their diaphragm has to be playing a big part of it.

[GobbleNut]

   Interesting discussion here,...with lots of theories!  For me, the question has always been about whether the vocal chords ("voice box") came into play in any of the sounds being made in the spit and drum.  To this day, I am not sure one way or the other. 

I do know there are three distinct sounds a gobbler makes in this process: 
The spit,...which I couldn't say for sure is caused by inhaling, exhaling, or by a burst of air through the voice box. 
The drum,...which I feel is a function of some sort of internal expansion of air in the chest area in some sort of body part that can inflate,...whether it be the lungs, the crop, the fat deposit, or a combination of any or all three. ...Not sure if I would call it a "vocalization" as relating to using the same mechanism (vocal chords) used in gobbling or other "turkey talk". 
The third sound is definitely the sound of the feathers "rustling" during the strut when the gobbler "expands" and "stiffens" his feathers. That is a more subtle sound, but it is certainly part of the entire display. 

[Cowboy]

From eating wild onions. Spit is a hiccup and the drum is indigestion.  That's why I scatter Rolaids and Tums around my tree....wait would that be considered baiting???  Honestly, the Ruffed Grouse comparison holds the best answer. Its internal definitely not feathers. The humming comparison is a good analogy as well.

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[Dtrkyman]

No way feathers are making that noise!


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[falltoms]

The deep guttural rattle that you hear at the end of a gobble when he is really close, has a vibration to it  like drumming. You can definitely feel it if he's close enough, maybe the two sounds are related on how he makes them. Vocal and internal at the same time.

[West Augusta]

I don't care how he does it. I just wish that I could hear it. I've never heard a gobbler drum.

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[Treerooster]

I don't know how it's done, if it came from the air in the crop, then they could only do it when it's completely empty, which first thing in the morning it usually is. I know gobblers don't eat much during breeding season, but they do eat some, it may come from the crop, but if there's any food in it, I don't know how that would work.
I think its a mystery, no one had figured out, and it should stay that way

Why does the crop have to be completely empty? Why not partially empty?

I haven't shot a whole lot of gobblers late in the evening over the years, maybe 15 or so??? I always check the crop of a gobbler I get later in the morning, afternoon, or evening. Not much in the crops late morning or the afternoon. I expected the late evening toms to have a decent amount of food in their crops, but that is not what I have found in my small sample size. I think the most I have found is a crop about 1/3 full.

Here is a tom's crop filled with air. I pumped some air in it with a compressor and while it is stretched out, it is not overly stretched. Pretty big and lots of room for some air and some food. Now I don't think the crop gets that big inside a turkey, but its not much smaller either. Never seen a turkey crop absolutely full of food, but I have seen plenty of ruffed grouse crops very full of food. They are much bigger than you would think relative to the size of the bird.

[GobbleNut]

I always check the crop of a gobbler I get later in the morning, afternoon, or evening. Not much in the crops late morning or the afternoon. I expected the late evening toms to have a decent amount of food in their crops, but that is not what I have found in my small sample size. I think the most I have found is a crop about 1/3 full.

Here is a tom's crop filled with air. I pumped some air in it with a compressor and while it is stretched out, it is not overly stretched. Pretty big and lots of room for some air and some food. Now I don't think the crop gets that big inside a turkey, but its not much smaller either. Never seen a turkey crop absolutely full of food, but I have seen plenty of ruffed grouse crops very full of food. They are much bigger than you would think relative to the size of the bird.

You have obviously delved into this topic to a greater degree than most of us, I think, Treerooster.   
Although I would not be so bold as to make a declaration of fact, I would surmise that your theory that the crop comes into play in this whole "turkey strutting noise" discussion is very possibly accurate. 

As for the tendency of gobblers to stuff their crops full to the brim, I would agree that I have rarely seen a full crop on a gobbler when dissecting the bird post mortem.  I must also readily admit that I have not been as conscientious about investigating that particular aspect of turkey dismemberment as you are.  However, there has been at least one occasion that a gobbler's crop was so full that it caught my attention during the butchering process.  That bird was stuffed full of dandelion flowers to a point that, if indeed the crop comes into play in drumming, he probably would have had to regurgitate some of them to do it!   

[Treerooster]

I always check the crop of a gobbler I get later in the morning, afternoon, or evening. Not much in the crops late morning or the afternoon. I expected the late evening toms to have a decent amount of food in their crops, but that is not what I have found in my small sample size. I think the most I have found is a crop about 1/3 full.

Here is a tom's crop filled with air. I pumped some air in it with a compressor and while it is stretched out, it is not overly stretched. Pretty big and lots of room for some air and some food. Now I don't think the crop gets that big inside a turkey, but its not much smaller either. Never seen a turkey crop absolutely full of food, but I have seen plenty of ruffed grouse crops very full of food. They are much bigger than you would think relative to the size of the bird.

You have obviously delved into this topic to a greater degree than most of us, I think, Treerooster.   
Although I would not be so bold as to make a declaration of fact, I would surmise that your theory that the crop comes into play in this whole "turkey strutting noise" discussion is very possibly accurate. 

As for the tendency of gobblers to stuff their crops full to the brim, I would agree that I have rarely seen a full crop on a gobbler when dissecting the bird post mortem.  I must also readily admit that I have not been as conscientious about investigating that particular aspect of turkey dismemberment as you are.  However, there has been at least one occasion that a gobbler's crop was so full that it caught my attention during the butchering process.  That bird was stuffed full of dandelion flowers to a point that, if indeed the crop comes into play in drumming, he probably would have had to regurgitate some of them to do it!   

Call me a "Bird Nerd" and I might blush with embarrassment from such a compliment. 

[RutnNStrutn]

I'm just jealous that you guys can hear so well. After 34 years in the fire department, I've got pretty bad hearing loss, as do a lot of my friends who were in the profession.
Usually by the time I hear drumming they're strutting into shooting range, and it's time to get down to business, not do a scientific study. The only time I hear drumming from far off is on cool, crisp mornings in relatively open woods.
I do however, tend to give more credence to the theory that drumming is internal and not vocal (through the vocal cords). In my opinion, the drum is just too deep and bass to come from the voice box. Especially when most other turkey noises that we do know are vocal are much higher pitched than the drum. As a couple of guys have commented, you can not only hear the drum, but if he's close enough, you can feel it. I don't think the feathers or the shaking create the noise. I believe they are a side effect of whatever internal action makes the drum.
Then again, I'm not a biologist. I'm just a hunter with hearing loss.

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[Old Gobbler]

Gobblers only do the drumming when they are in full strut

IMO I think the gobblers inhale air or ...hold onto Thier breath into Thier body to puff them selfs up ...when the drumming sound occurs you see a bit if "shuddering" ...I think the sound is a form of slow air belch escaping from Thier body past Thier vocal chords