They might be associated with trawling through your trash, but raccoons are actually pretty hygienic critters. When a lot of them are living in the same area, they all tend to poop in the same place, and it turns out that these raccoon toilets generate an ecology of fear.
Known officially as latrines, these piles of poop can be either a smorgasbord for some animals or a hazard for others. This is because while the raccoons pass a lot of nuts and seeds with their feces, which can become a food source for those so inclined, they are also riddled with parasites.
After spending years staking out raccoon toilets, researchers have found that these latrines offer an easy picking for some species, but that many steer well clear due to the process known as the "ecology of fear". The results have been published in Oikos.
This is where certain species will change their behavior or movements due to a perceived threat to their environment. In the case of raccoon toilets, it seems to be the risk of disease and parasites. Camera traps revealed that while the hardy rat would quite happily dive in and out of the poop chomping on bits of it, those species such as birds and rabbits that can catch the roundworm raccoons carry steered well clear.
Researchers are slowly understanding just how prevalent and widespread the ecology of fear is, and how it can alter not only the behavior of animals, but the geography and landscape of a place too.
The most famous example is that of reintroducing wolves into Yellowstone, but a similar effect has also been found with tiger sharks in Western Australia. These predators prowl the underwater meadows in search of food, meaning that the turtles and dugongs that eat the grass are never in one place for a long period of time, and therefore the seagrass is never over-grazed.
This study took things a little further, investigating how the ecology of fear linked in with that of parasites, in turn assessing how disease can shape an ecosystem. When this is taken into account, it can help explain a whole host of otherwise intriguing puzzles in ecology. For example, the carcasses of herbivores are quickly scavenged, while those of carnivores are left to rot, and thus are a better supply of nutrients for invertebrates and plants. This is likely due to other carnivores avoiding the remains due to the high chance of catching diseases from them.
It seems that this behavior may be far more prevalent than is thought, and could be influencing a whole host of processes.