Deer and Their Hearing

Although deer season started in some areas of Idaho a few weeks ago, deer season started on October 10 in most areas. And, of course, there are some areas where archery season runs into late November or even into December. Thus, some of you may find the following article useful: it is "Deer Trust Their Ears" from American Hunter and discusses some research into how deer use their hearing.

    One of the first points, and an important point, is that a deer's hearing is, in some respects, not much different than a humans.

      The study’s lead researcher, Gino D’Angelo, and his team learned a deer’s hearing range extends from .25 kilohertz to 30 kHz, but it hears best in the 4 to 8 kHz range, which overlaps the primary sound range of the whitetail’s vocal communications. Specifically, of 12 identified whitetail vocalizations in previous research, most had frequencies of 1 to 8 kHz.

     Those frequencies differ little from human hearing, which is best between 2 and 5 kHz, with an upper range of about 20 kHz. Still, the UGA researchers noted that deer can detect higher noise frequencies than humans, but pinpointing that exact high-frequency range required further research they couldn’t conduct.

But the article also relates some conclusions from other researchers who tried to pinpoint the upper range of hearing, which turned out to be 64 kHz. In short, based on the research, "[d]eer have better high-frequency hearing than do humans, but worse low-frequency hearing."

     The advantage deer have are large outer ears that are cupped to better collect sound, and that can be swiveled in different directions. But this can be a weakness because, if their ears are facing one direction, their ability to collect sound from the other direction is diminished. And, just like us, a deer's ability to hear something can be impacted by various factors such as wind, humidity, air temperature, vegetation, ground cover, and overhead foliage. Thus, you will sometimes read that the best time to hunt deer may be during a light rain or immediately after, when leaves and other debris is soggy so it won't crunch or make noise, but it also absorbs sound. A snow storm can similarly reduce deer's ability to hear well.

       But it isn't just hearing that helps deer evade shots, it is also their instantaneous reaction. Simply put, deer get off the X as quickly as they can. As the author relates:

     No whitetail that hears a bowstring’s slap at close range pauses to weigh its options. And no deer that hears a coat sleeve catching on overhead bark seeks second opinions.

     In the first case, the deer instinctively drops low and springs into flight, sometimes never looking back to see what scared it. In the second case, the deer typically snaps to attention, its ears swiveling and triangulating while its eyes and nose probe for answers.

     Unless you’re hunting with a firearm and it’s already shouldered, you’ll likely have to concede the contest or risk a running shot. When deer hear unnatural noises inside their innermost security boundaries, they instinctively flee or snap to full alert. ...

The dropping low reaction is particularly important to bow hunters because a deer might duck under the path of an arrow before the arrow reaches it. Thus, it is important that bow hunters choose a set up that maximizes flight speed. The article also notes that technological advancements have made available fabrics that are quieter--as much as 1/2 has quiet--as "older tech" fabrics.