It’s Not Aggression—It’s Instinct: Why Dogs Bite Delivery Workers

Every day, delivery workers face the risk of being bitten by dogs—not because these dogs are bad or aggressive, but because their natural instincts take over. Unfortunately, many dog owners don’t see it coming. They believe, “My dog would never attack anyone,” simply because their pet has never shown signs of aggression before. But the truth is, instinct runs deep in dogs, and when a stranger steps onto their territory, those primal survival instincts kick in.

Dogs have survived on this planet for millions of years because of these instincts. One of the clearest examples is their territorial marking behavior. When a dog pees around your yard, it may seem like a harmless or even funny quirk to us, but to your dog, it’s serious business. Marking territory is an ancient practice rooted in survival. It tells other animals, “This is my space—keep out.”

The same instinct is at play when a delivery person enters the dog’s space. Even if a dog has never acted aggressively before, they might perceive the delivery worker as a threat. To the dog, the sudden appearance of a stranger triggers the need to protect their home and family, which can lead to an impulsive bite.