The Longbow - Here Comes The "Pitch", No Silencers

The hunter alert and on one knee struggles to keep the shakes of excitement at bay as the young buck feeds slowly toward a shooting lane through the multiflora.  With a final step, the wait has ended, and the arrow is drawn and smoothly loosed only to lodge in the ground beneath the startled deer.  Turning ends in midair, the buck takes a leap and then freezes.  Minutes tick by as both hunter and deer try to decide what to do next.  Finally, the buck walks nervously over to the where the sound of the arrow impact happened and sniffs around.  By this time the hunter has regained his composure, withdrawn another arrow from his quiver, and this time he does not make the same mistake twice.  The hit is good behind the crease of the front leg and the deer does not go far.  Does this scenario sound familiar to anyone else?  Well, there may be something going on other than just the lack of smarts on the part of a young buck.

I have been dedicated to hunting for many years now with what is known as the American Semi longbow (ASL), also known affectionately to its devotees as the "Hill" style longbow. I have always received questions from others inquiring why I don't have string silencers on my hunting bow.  My answer most times is something like "Well, I never felt the need for them", or "I like simplicity, and I don't want extra stuff hanging from my bow if I can help it".  Since my stint of hunting with recurves for a few years, and then returning to the longbow, I have noticed an increase in follow up shot opportunities when I  do miss.  There may actually be a scientific reason why.

At work I was recently asked to perform some sound level monitoring in the animal housing areas where construction activities were occurring in other parts of the building.  The sounds were not bothersome to the human caretakers or researchers, but they were stressing the animals.  While doing some research on the subject I came across some interesting information with usefulness to the hunter.

Animals can hear high frequency sounds that humans cannot as referenced by the right side of this chart below:

Turner et al., 2005; Adapted from the works of Richard Fay, Henry & Rickye Heffner, and others

This got me thinking that deer might also be affected more by higher pitched sounds that are outside of our ability to detect.  I found a research paper that specified just that. 

H. Heffner, Jr. and H. E. Heffner: JASA Express Letters DOI: 10.1121/1.3284546 Published Online 11 February 2010

Another paper showed how high pitched sounds that were imperceptible to humans can cause a stress response in animals such as an increase in blood pressure on a study of desert mule deer.

So our game animals do notice high pitched sounds in an adverse way that we cannot even hear.  In fact, deer have a better ability to hear higher pitched sounds and a poorer ability to discern low frequency sounds as compared to you or I.   I would have never guessed humans might be able to hear better than a deer, but for lower frequency sounds this is true.

Higher frequency sounds are also very directional in nature.  They are so directional that they can be used in our measuring instruments and by motion detectors that control the door at the supermarket.  Therefore, if an animal does hear a higher pitched sound, it is more likely to be able to pinpoint your exact location faster.  These adaptations no doubt evolved over the millennia to increase the deer's ability to discern the exact location of a predator by the crack of a twig in an instant. Yet this also explains why after a low grunt, a buck will often come in looking around in all directions for the animal that made the sound.

This knowledge has all sorts of implications for the thoughtful hunter.  The clank of an aluminum arrow off the rest, the jangle of keys or change in your pocket while walking, the chatter of our aluminum stand on a branch may be akin to shining a spotlight on your location.  Conversely the deep muffled cough in your sleeve as your allergies react to the musk of decaying leaves in the fall might not be as big a deal.

Then there is my beloved longbow.  Considered slow and inefficient by some compared to modern bow designs, it's long and fat elastic dacron string creates a deep low hum when shot.  It is quiet without the need for string silencers, but it could actually be even quieter to a deer than it is to you or I.  Something to think about now that the current trend in traditional bows is short compact equipment with skinny low stretch strings.