Generally speaking, white-tailed deer keep to themselves; and they don't stir up much trouble with people - at least not outside of growing sites; but there is one special time of year where we see an increase in deer aggression.

Late spring is when doe give birth to babies; and mother deer will act out on people, pets and other types of wildlife if they get too close to fawns. This is out of self-defense as doe's maternal instincts quick into gear. 

In late spring,outdoor enthusiasts may find fawns alone in grassy and wooded areas; but it's best not to approach fawns - mothers are close by scouting for food to bring back to their babies and left fawns behind where they can be hidden away from predatory wildlife. 

Deer aggression rises late spring. If fawns are seen left alone, leave them be and contact local DNR for support.