First of all, check and see if you find any non-cache boxes labelled "ACME" nearby. If so, the coyote might be using any one of a variety of gadgets that may explode at any time. Exercise caution. Also, if you happen to hear a "MEEP MEEP" sound, you are dangerously near the coyote's prey. You'd be advised to take shelter immediately as you could accidentally wander into the path of falling boulders from cliff escarpments.
But seriously...just think of "special effects". EFFECT is more commonly a noun, whereas AFFECT is more commonly a verb. There are exceptions, but it's a good rule of thumb.
HTH!