Meet the 'Elepaios
by Nate Swick
At the Mic: Eric VanderWerf
Eric's post is a companion piece to his article in the July 2012 issue of Birding.
Cool/interesting things about 'Elepaios that I have observed/learned during the past 20 years in which I have studied them:
1. They are bold and curious. They often investigate unusual sounds in their territory, including human voices. They may follow you along a trail through the forest, and if you sit down to have lunch they may come and peer at you from over your head. This makes them fairly easy to see, and to get a good look at.
2. They use an amazing variety of foraging behaviors, perhaps wider than any other bird; they catch insects in the air like a flycatcher; they glean insects off leaves like a warbler, they cling to trunks like a nuthatch, they hop on the ground like a thrush, they hang upside-down like a chickadee. See this reference: VanderWerf, E.A. 1994. Intraspecific variation in 'Elepaio foraging behavior in Hawaiian forests of different structure. Auk 111:915-930.
3. They are the only Hawaiian bird that has been observed "anting". Objects used for anting have included ants, toxic millipedes, garlic snails (which smell like garlic), and poisonous fruits. None of these objects are native to Hawaii and have been here less than a century, so 'elepaio have recognized the chemical properties in these foregin objects and learned to use them. See the following reference:
VanderWerf, E.A. 2005. Elepaio "anting" with a garlic snail and a Schinus fruit. Journal of Field Ornithology 76:134-137.
4. They have withstood the onslaught of threats that have decimated the avifauna of Hawaii and are one of few Hawaiian birds that have adapted to non-native forests and are found at low elevations where mosquitoes are common. Even if most Hawaiian birds go extinct, I think at least the Hawai'i 'Elepaio and Kaua'i 'Elepaio will still be with us. I and others are working hard to make sure the O'ahu 'Elepaio sticks around too. The 'elepaio are making an effort too, see the following reference about evolution of nesting height in response to predation by rats: VanderWerf, E. A. 2012. Evolution of nesting height in an endangered Hawaiian forest bird in response to a non-native predator. Conservation Biology. DOI: 10.1111/j.1523-1739.2012.01877.x
6. They can live more for than 20 years. There is a Hawai'i 'Elepaio at Hakalau Forest National Wildlife Refuge that I banded in 1994 and that a friend of mine saw this year. It was at least 3 years old when I banded it, so it is at least 21 years old! For such a small bird (15 grams) they are among the longest-lived bird in the world. I know of 2 more that O'ahu 'Elepaio are at least 19.