ok, So I love telling this story, but this is one of my best stories, and funniest, esp in person, that I have.
When I was with my National Guard unit I was assigned as a M249 SAW gunner. Yep, the Army trusted me to give me a fully automatic belt fed machine gun. This would have been October 2004. We were at Ft. McCoy Wisconsin for Battalion Weapons Qualification. All the SAW gunners went off to the Machine gun range, The officers to pistol and the majority of the BN to Rifle. We were a standard light infantry battalion, 3 companies light, one company anti-tank.
Anyways, we go through all of the zeroing and grouping and such for the M249. There's a good batch of fresh/first time shooters, myself included. So we are out there and we get through the 25m zero and group just fine. Now it's time for the pop-up 'live' qualification of the range. M249s closest target is 400m and furthest is 800m. The one advantage is you have a spotter assisting you with your qualification, they make sure you are engaging the right targets, assist if you are off and such. Normally it's your battle buddy, but since all of our battles were off at the M16/M4 range, we were spotting for each other, mainly the experienced guys spotting for the new guys.
Now remember, this is Wisconsin, this is the national guard, we got some good old northern boys.
About halfway through the iteration, the 600m target pops up. Now, keep in mind, this is with iron sights. as I engage the 600m target, the pop-ups (there's 2-3 standard silhouettes together) drop down, and the dirt behind the target shifts. In the middle of the day, after a number of SAW gunners have already shot, a deer had wandered out onto the range and taken up munching the grass behind my 600m target. Figuring I had already put a few rounds in, and with the prompting of my spotter suddenly yelling " HIT THE DEER HIT THE DEER HITTHEDEERHITTHEDEER!!!!" I learned more in those two 15-20 round bursts of walking rounds into a target than I ever have, or ever would.
Thankfully the Range Control/OIC either completely missed it, or ignored it.
But just goes to show that when animals get used to stuff, they get used to it.