Japanese White-Eyes at Hawai'i Volcanoes National Park: Sometimes it's the Point of View

What's the most populous bird on the Hawaiian Islands? Visitors might suspect Mynas or Zebra Doves, given their ubiquitous presence in the tourist areas of the islands, but it's quite possibly this one, the Japanese White-eye (Zosterops japonicas). They are pretty little birds, but tend to be hard to see in the vegetation given their green color. There may be hundreds of thousands of them on the islands, and they can be found from sea level to 9,000 feet, and in both dry and wet forests.

It would be nice if they were one of the native species of the islands, but alas they are not. They were introduced in the late 1920s to help in agricultural pest control, but in a sense they themselves became pests. They may be a vector in spreading avian diseases, and they have been documented exploiting food sources in the higher altitude forests at the expense of native species.

Still, as with many of these invasive species, they are colorful and fun to watch. I saw this pair while walking through the "Bird Kipuka" (Kipuka Puaulu) in Hawai'i Volcanoes National Park on the Big Island. My previous post on the species had the better pictures (see it here), but this pair was doing something that was unusual looking. It appeared that one was grooming or picking lice off the other. I don't know for sure, but I'm sure there's someone out there who can tell me what they are doing.

I shot a short video to provide some more context. Enjoy!

Japanese White-Eye at the Kona Farmer's Market

Bird-watching in Hawai'i can be frustrating. There are a great many colorful and easily seen birds, and there is the quandary of knowing that most all of them are introduced and invasive species. The native birds are rarely seen, as they have drastically decreased numbers, and have been driven into last stands in the high elevation forests. Many of them have gone extinct already.

Bird malaria is one of the worst causes, but there are many others. By the 1920s, so few native birds were found in the coastal towns that well-meaning people brought in tropical species to fill the void. Other birds were introduced to help control insect pests in the pervasive sugar cane fields. One can see the point of choosing non-native birds versus no birds, and one can also realize the lack of research that would have warned against introducing new species without understanding the potential negative effects.

Probably no bird illustrates the quandary so well as the Japanese White-eye or Mejiro (Zosterops japonicus). It arrived on the islands in the 1920s and 1930s for insect control purposes, and for better or worse it was a perfect fit for Hawai'i. It spread beyond the cane fields and into the montane forests, and is now the most populous land bird on the island. It is omnivorous, meaning it competes with numerous other native birds for insects and fruits. It may be a vector for bird diseases.

Who, me??

And yet...it's a beautiful bird, and fun to watch as it hangs upside down to snatch seeds.  It's said to be a beautiful singer, and there is emerging evidence that it might have become a pollinator for some native Lobelioid species whose original pollinators have gone extinct. Endangered native Hawaiian Hawks have started preying on them.

In any case, they are on the islands to stay, for better or worse. And they may be filling the environmental niche left behind by the sadly extinct native birds. And if you think about it, the most populous bird on the island could have been something far more obnoxious (I think of European Starlings on the mainland, for instance).