Honolulu Magazine's most recent issue has a fascinating article about Eric VanDerWerf, a biologist studying the endangered (on Oahu) 'Elepaio, a beautiful forest bird only 5 inches long.
VanDerWerf uses the songs of the 'Elepaio to study speciation and survival rates. The birds use their songs for attracting mates, defending territories, and species recognition. The bird is endemic to the Hawaiian Islands, and there are 3 subspecies - Kauai, Big Island, and Oahu.
He played the recorded songs to determine if the Oahu 'Elepaio, for instance, would react to the Kauai bird or Big Island bird. He found “The birds responded to their own island, but generally, not to the other islands. That means they don’t view those birds as potential mates or competitors, so that’s evidence that they should be considered separate species.”
The bird's biggest threat is predation by non-native black rats, that find the nest, eat the eggs and chicks and female, if they can catch her. Avian malaria and pox virus are also major threats, carried by mosquitoes, which can't live in the cooler temperatures in the mountains above 5,000' found on Kauai and Big Island. That explains why there are only about 1500 birds left on Oahu, but many thousands on the other islands.
VanderWerf admits that although he has done research on other birds, he has an affinity for the 'Elepaio. “They have a lot of character and interesting behaviors,” he says. “And because they are declining there is a real need for information about them.”
Read the full article in the print issue of Honolulu Magazine, or online where you can listen to the calls of the 3 subspecies.