Great question Rob, I have been wondering that myself. With all of the video footage shot in the last 5-10 years, why has noone heard the growl? I guess it is a new breed of deer that startedstarted a new language.

I did see a bioligist on one of the huntin shows talking about it. I think it was a DruryBro. show. So that may explain his answer.He said it was due to the intense management creating more competition between the bucks. Thus they are getting more aggresive with their vocalizations. But to my Knowledge bucks have been aggresive to one another during the rut for a good while.