A Bunch of Bulbul: Invasive Species on Oahu

Yes, you can think of this blog post as being a bunch of bulbul, because it has pictures of not one, but two species of Bulbul, an invasive species that arrived illegally on Oahu in the 1950s, and quickly established itself as an agricultural pest. It has not managed to spread to the other Hawaiian Islands yet, although a few individuals have been sighted on Molokai and the Kona Coast of the Big Island. The two species are the Red-whiskered Bulbul (Pycnonotus jocosus), and the Red-vented Bulbul (Pycnonotus cafer). I think the bird in the picture above is a juvenile Red-vented Bulbul. It's the only good picture I've managed over the years, taken at Waimea Valley in 2010.

The rest of the pictures are from my most recent trip, and are also from Waimea Valley on Oahu. Above and below are some shots of the Red-whiskered Bulbul, while the last shot below is a Red-vented variety.

So on an island where most of the birds are non-native species, why does this one stand out as a pest and a dangerous invasive species? The state of Hawai'i gives three reasons: They are pests of agriculture and gardens, feeding on fruits, vegetables, flower buds, and insects; they spread the seeds of invasive plants, including miconia, ivy gourd and false kava; and they aggressively chase other birds and compete with them for food and space. There is concern that they may compete with native birds where they co-exist. The Red-vented Bulbul has actually achieved the dubious distinction as being one of the World's Worst Invasive Alien Species.

Let's hope they stay put...

Cattle Egret in Downtown Honolulu

I'm back from another long trip, this time across the Pacific Northwest, and Wi-Fi was hard to come by in the wilds we were exploring. But now I can continue our exploration of the birds of Hawai'i, and then move on to the Pacific Northwest species I was able to photograph during the last two weeks. Today's species is the Cattle Egret (Bubulcus ibis) that I was able to shoot while strolling through a coastal park in downtown Honolulu.

The Cattle Egrets have an uncomfortable history with Hawai'i. They originated in Africa, spread to north and south America, and were introduced for pest control purposes in Hawai'i in 1959. They did their job, inhabiting pastures and fields, picking off flies and other biting pests. But as agriculture has decreased, and interest in preserving the native species increases, the Cattle Egrets have become a problem, as they compete for food resources, and pick off the eggs and chicks of native species on the islands, especially the Stilts and Coots.

Established and Spreading Fast, the Kalij Pheasant on the Big Island

Once again, in the category of "it seemed like a good idea at the time", someone decided to release a few dozen Himalayan pheasants at the Pu’u Wa’awa’a Ranch on the Big Island of Hawai'i. I'm guessing it was for hunting purposes. They didn't do much for a decade or so, but they reached some kind of population tipping point and began to spread. Their range has expanded across most of the forestlands of the Big Island, and a few have been seen on Maui and Oahu. These are the Kalij Pheasants (Lophura leucomelanos).

 I've seen them most often at the Bird Kipuka (Kipuka Puaulu) in Hawai'i Volcanoes National Park. They certainly add a splash of color to the forest floor, but their role in spreading disease or disrupting food sources for the native bird species is not clear. They sure are a shock when you are walking along a trail looking up and practically trip over them.

African Silverbills at Laupahoehoe and Kona

Our journeys through the Hawaiian Islands brought us to the beach park at Laupahoehoe northwest of Hilo on the Big Island. The park preserves the memories of a tragic event in 1946, a tsunami that took the lives of 20 schoolchildren and four teachers (story here). I wandered towards the beach area and saw a small flock of African Silverbills (Lonchura cantans), also known as Warbling Silverbills.

Most of the birds that one sees in the urban and coastal settings are not native to Hawai'i, and that is the case here, if you couldn't figure it out from the name. The birds seem to have arrived in the 1960s, probably as escapees from pet owners. They have spread throughout the entire island chain. I saw others on the road to Kona below Saddle Road (below).

A Reasonably Polite Invader in Hawai'i: The Zebra Dove

There is a cooing sound that starts the day in the lowland towns  of the Hawaiian Islands. It doesn't take long to identify the singer: it's the Zebra Dove (Geopelia striata). Even if one misses their morning song, they'll make themselves known as you try eating in a park or outside diner. They are one of the most common birds seen in Hawai'i.

The Zebra Dove arrived at the islands in 1922 in a shipment from Singapore. They are native over a wide swath of southeast Asia. They quickly established populations on all the islands almost to the point a being a nuisance (but most of them have been polite to me!).

Photo by Mrs. Geotripper

As almost always happens, I took practically no pictures of the single most common bird I saw during my recent trip! The first two pictures are from an earlier journey on Oahu, the third is from Mrs. Geotripper from the Kona area, and the fourth (below) is a shot I took at Kona as well.

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).

Land of the Lost, the Birds of Hawaii: A Blog Series

Hawai'i is one of the most isolated landmasses on planet Earth. Surrounded by thousands of miles of open water, it's kind of amazing that any animals or plants thrive there at all. Instead, the islands have an incredibly diverse and complex ecosystem. Most of the endemic species in the United States occur on these small islands (endemic species are those that are found nowhere else in the world) . When plants and insects are included, the number of species are in the thousands.

How did all these species get here? The answer is...strange. They didn't all get here. A few of them got here, and the survivors changed and evolved into new species better adapted to the new environment they faced on the islands. Hawaii as a laboratory for evolution is in many ways the equal of the more famous (to biologists and geologists) Galapagos Islands.

Hawaii truly is the land of the lost. The animals that reached these islands prior to human colonization were blown off course and somehow survived a harrowing journey of several thousand miles over the unforgiving sea. Millions of birds of birds have become lost over the oceans through the endless years, and only a vanishingly small percentage are ever lucky enough to make landfall. The rest perish. By one estimate I've seen, a new bird species arrives by natural processes only once every 20,000 years.

The birds of Hawai'i were one of the nicest discoveries of my six visits to the islands. I can point to my Hawaiian experiences as the beginning of my interest in birding. I find their stories to be fascinating, and I am looking forward to seeking them out again. I'll have a chance (and so will you) next summer, as we will be offering a field studies course on the islands from June 1-14, 2016. To celebrate the coming trip (and I guess to celebrate one year of bird blogging), I'm going to be offering a series of posts on the birds of Hawaii, both the native species and some of the interesting invaders as well.

It being my habit to be easily distracted, the series will be off and on as I get the time. I hope you'll enjoy! Aloha!

Great-tailed Grackles Return to CSU Stanislaus

The pond outside my office at CSU Stanislaus was a great deal noisier this week. It didn't take long to find out why. The Great-tailed Grackles (Quiscalus mexicanus) have returned north from their winter homes. The region was feeling a bit empty after the geese and Sandhill Cranes left for the Arctic over the last few weeks, so it's nice to know that other species are coming here for the summer. They have a piercing whistling call that echoes across the pond.

You can tell they put their all into shouting at each other...

The Great-tailed Grackles are a newcomer in our region. Unlike many bird species, they have been vigorously expanding their range over the last few decades. In this case, they are not exactly an invasive species in the manner of Starlings or Eurasian Collared Doves. They are native to northern Mexico and the border states, and they do well in association with humans, especially their parking lots and garbage cans. This report (click here) outlines the nature and timing of their expansion.

The males are iridescent black and are much larger than the females, who are more of a buff color (above). And they have amazingly big tails that look out of proportion to their bodies. They breed in a number of environments, but seem to favor reeds and cattails like those that are found on the margin of the pond at the CSU. As such, they may compete with Red-wing Blackbirds. In any case, with their distinctive call, they have the effect of livening up the place.

Bird of the Day: Another Foreigner, the Eurasian Collared Dove

In the mid 1970s, the Eurasian Collared Dove (Streptopelia decaocto) was only present in the western hemisphere as a pet.  In Bermuda, the burglary of a bird shop led to the release of several doves, and for some reason the owner let the other 50 go. In the 1980s, the first Eurasian Collared Doves arrived in Florida, and now have spread across the continent, except for the Great Lakes and New England. They were in California by 2001.

I've only been at this for about a year, so I thought the doves in my neighborhood were all of the mourning kind, but I've come to realize that most of them are the Eurasian species. It's not clear if they have displaced other birds the way the European Starlings have, though. The doves are mostly taking advantage of food sources related to urban and suburban development, including feeders.

I remember the most stunning fact of birding on the Hawaiian Islands is how hard it is to actually see the native species there. The escaped pets and accidental/purposeful introductions of invasive species have simply overwhelmed the natives in the urban parts of the islands. The rapid spread of the Starlings and Collared Doves in the continental United State is concerning.

In any case the doves, if not exactly tame, are tolerant of walkers with cameras and are usually easy to photograph. I caught the first image this morning while walking in the pasture near my house. The second picture was taken in December around the same field. The birds are apparently permanent fixtures around here, despite their fairly recent arrival. And they are pretty to look at.