I moderate a Flickr group called “Snakes eating in nature.” The group contains many wonderful observations of different snakes and the prey they catch in the wild. After the group passed its first 1,000 contributions, I posted a few examples of predation by snakes that can be seen in the group.
Some of the cool observations in the group involve native snakes eating introduced (and even invasive) prey. An example is this photo of a northern water snake eating an introduced round goby by Elizabeth Nicodemus :
Here’s another photo of a water snake eating an introduced goby. The photo was taken in Collins Bay, Ontario, by Allan Lance:
It turns out that introduced gobies have become a large part of the diet of some populations of water snakes. King, Ray and Stanford published a paper about the diet of the Lake Erie Water Snake. Prior to the spread of the round goby, Lake Erie Water Snakes primarily ate frogs, toads, mudpuppies and native fish. Since the spread of the round goby, Lake Erie Water Snakes are now mostly (~ 90 %) eating round gobies! The inclusion of round gobies into the diet of the Lake Erie Water Snakes is also associated with increased snake growth. So the introduction of the round goby might actually be helping the Lake Erie Water Snake populations. Although they may be beneficial to Lake Erie Water Snakes, the round goby still has negative effects on other organisms in the Great Lakes ecosystem.