In the 90s, there was a study by the Smithsonian, where they compared wild areas with deer and where deer were blocked out (West Virginia, I think). They found that deer reduce the number of small mammals and birds each by about 90%.
The study also noted that the are places where there has been no young tree growth in over 20 years as the deer eat all the saplings. Deer also don’t really wander far until they hit overpopulation and move to find food.
They run around our streets and rip up our plants at night, in huge groups.
When no-ones watching the be-be gun is fun to play with.
Plenty of Lyme disease here too.