These wolves wiped out every deer, then turned to an unexpected new prey

On the remote island off the coast of Southeast Alaska, nature's wildest drama unfolded in the ecosystem. A pack of wolves arrived at the island in 2013. They found a paradise, a fertile ground for hunting, filled with herds of black-tailed deer. Apart from the deer, the island hosted a plethora of animals otters, red squirrels, and even brown bears. But then a natural experiment unfolded. As the new predator arrived, the ecosystem hit an impasse. The wolves started to colonise the island.

"We were interested in seeing how the newly colonising wolf population would impact the deer population and predicted that the wolves might eat all the deer, and then leave the island as it is only separated from the mainland by 1.5 km,” says Roffler Gretchen, who was keenly observing the predator-prey dynamics.

The deer population, 120-200, declined within a few months. However, as they wiped out the entire deer population, scientists predicted that they would move to a new location. But what happened was completely unexpected.

Researchers from Oregon State University used GPS collars and analysed DNA from wolf scat. They discovered that these land predators had adapted to their new environment. Instead of abandoning the island, they switched to a different prey, but not on land. It is on the water. They went after the sea otters.

By 2018, nearly 67% of the wolves’ diet was sea otters. But it also raised serious ecological concerns. One wolf was found dead due to mercury poisoning. This was due to the wolves’ diet. Even though the change showed the adaptability of the wolves. The changes in the food habits and shifting to a marine ecosystem induced mercury toxins, a toxic metal that accumulates in marine food chains.

It began as a textbook example of predator-prey dynamics, soon collapsed and became a story of survival. This unusual shift provides a long-term shift to both predator and prey behaviour and posing a risk for ecosystem stability in both water and sea.