ive had coyotes act agressive in traps, growl,howl,snarl& bear teeth & coyotes growl & yelp cause they got to close while i was calling when they realized oh! crap that rabbits freakin huge, but the most agressive coyote ive delt with was a female inside a den, i killed the male near a den id found & the female was inside, unbeknown to me, i was crawling inside to retrieve the pups & i had to yell & throw dirt in her face as i backed out, she got within inches of my face, luckily i had a 22mag pistol with me so i crawled back inside pistol drawn this time & shot her when she came at me again,she had 5 pups in that den with her, this took place around the 1st week of July a couple years back while doing a damage complaint on a cattle farm, the farm manager located the den when he was checking cows & his aussie dog got to close to the den & was attacked the coyotes didnt even pay attention to his yelling they were set on driving away the other canine from their den site.