If you thought that humans can be tricky and complicated when it comes to answering nature’s call, you should hear about our canine friends and their weird and sometimes absolutely baffling ideas and habits.

There are a number of factors that will influence how a dog answers to the call of nature – from its breed to its age, from the weather to the location and so on. In short, dogs can be picky poopers.

The reason for this, according to the director of Small Behavioral Service at the University of Pennsylvania;s veterinary hospital, Carlo Siracusa, is that dogs are not just leaving waste behind. In fact, they are leaving piles of information on the ground; information that will be of interest to other dogs in the area.

Carlo says:

“These messages can tell your dog how many other dogs are in the immediate area, the sexual status of those dogs—whether a female is in heat, for example—whether a particular dog is a friend or an enemy, what he or she had for lunch, and when they were last in the area.”

Another expert, Melissa Bain who works at the Clinical Animal Behavior Service at UC Davis’ School of Veterinary Medicine, our dogs develop their preferences at a very young age, mostly notably about the type of surfaces where they prefer to do their business.

She says:

“They seem to prefer softer substrates, if they have the opportunity to use them. They are also attracted back to the area on which they eliminated before, so if it smells like urine or feces, they are attracted to go back there (providing it’s reasonably clean).”