Native to the mountains of India and Pakistan, Kalij pheasants were introduced to the Puʻu Waʻawaʻa area on the island of Hawaiʻi in 1962. (Sound familiar?)
Since then, these game birds have colonized the high elevation forests on the Big Island, Maui, and Oʻahu. Unfortunately, they tend to bring invasive species with them. Kalij feed on the fruits of Banana poka, strawberry guava, and clidemia, and as a result, they spread the seeds of these destructive plants throughout our native forests.
But Kalij pheasants aren't just changing the landscape in Hawaiʻi — they're changing their breeding behavior as well.

These pheasants are predominately monogamous in Asia. But in Hawaiʻi, researchers have observed the emergence of a new social system: dubbed "cooperative breeding," one female may form long-term bonds with up to six males. Though they may compete for dominance within their group, all the males all pitch in around the nest.
Kalij likely adopted this forward-thinking attitude towards polyandry as a result of overcrowding. Since there are so many of these pheasants in our forests, there's insufficient territory for them to maintain monogamous behaviors.
Audio credit: Doug Pratt/Macaulay Library at the Cornell Lab of Ornithology (ML5281)