RESEARCHERS SEEK MORE INFO ON ‘PEPE AE’— KNOWN TO EXIST ONLY IN TUTUILA
The Department of Marine and Wildlife Resources (DMWR) is collaborating with the American Samoa Community College’s Land Grant Program, the United States Geological Survey (USGS) Pacific Island Ecosystems Research Center, and the National Park of American Samoa, on the Samoan Swallowtail Butterfly Project.
DMWR’s division head and wildlife biologist Adam C. Miles said in an email to Samoa News earlier this week that they are working together to understand the threats and limiting factors of the Samoan Swallowtail Butterfly.
The Swallowtail is the largest of the Samoan butterflies. Its wingspan can be up to five inches and it is so large and quick that, in flight, it can sometimes be mistaken for a small bird. The Swallowtail is mostly black with some white and red marks and distinctive tails on the hind-wings, thus the name “swallowtail.”
The Samoan Swallowtail Butterfly or pepe ae (Papilio godeffroyi) is only found in the Samoan archipelago and— of all the places in the world— is currently only known to exist on the island of Tutuila. According to Miles, the last confirmed sightings of the butterfly in the Samoan Islands of Upolu and Savai’i occurred over 33 years ago, back in 1979.
The pepe ae is a large, colorful butterfly which can be seen flying within and on the edges of rainforest throughout Tutuila.
The Samoan Swallowtail Butterfly Project has a few main components. First, the group is mapping Micromelum minutum (Talafalu), the only known food plant of larval Papilio throughout the island.
“We are selecting sites with varying abundances of Talafalu, and then plan to monitor these sites throughout the year for tree flowering or fruiting, and presence of eggs, larvae (caterpillars) and pupae of Papilio,” Miles explained. “We are trying to get a better understanding of important habitat characteristics that drive Papilio egg and larvae distribution on the food plant.”
The other main component of the project is collecting eggs and larvae in the field, and rearing them at the ASCC Land Grant laboratory. Miles said the purpose is to investigate parasitism of the eggs and larvae. “One theory is that parasitoids could be (at least partially) responsible for the decline of Papilio in Samoa. This will also give us the capacity to breed the butterfly which could aid in future reintroductions to Samoa,” he said, adding that they are also working on a method to monitor the abundance of the adult Papilio, but this is a difficult task with a fast moving and relatively rare butterfly.
Miles said DMWR, ASCC Land Grant, and the National Park are currently selecting sites for monitoring. The agencies visit the sites together to measure habitat characteristics to ensure data is collected in the same manner. Each agency then plans to monitor their sites on a monthly basis, collecting data in the same manner, and searching for eggs, larvae, and pupae.
Miles explained that the ultimate goal of the butterfly project is to determine current threats to the Papilio population, understand how the food plant drives distribution, and determine if re-introduction to the independent state of Samoa is possible.
So has there been any progress? Miles says that DMWR has identified sites in the eastern half of Tutuila Island, with the ASCC Land Grant identifying sites in the west, and National Park identifying sites within the National Park of American Samoa. “We began measuring site characteristics in March, and monitoring should begin shortly,” Miles said. “We have currently located only a few larval butterflies, but expect this to increase in the next season.”
The Samoan Swallowtail research has been ongoing since 2009 and included some mapping of Talafalu along roads, and recording observations of adult butterflies. Visits to Samoa to look for the butterfly were also conducted in 2009, though no Samoan Swallowtails were seen there at the time.
The current research—as a partnership between DMWR, ASCC Land Grant, USGS, and the National Park— began last October. Earlier this year, the group began searching for Talafalu and site selection with visiting scientists Bob Peck and Paul Banko of the USGS Biological Research Division. Miles said it would be helpful for the public to be careful about cutting down Talafalu when clearing along roads and plantations.
Currently, there is no way to estimate a total population count. Miles said that while they continue to investigate methods to get a population estimate, it may not be possible with a butterfly that is rare, and flies so fast and so far.
“We are hoping that by monitoring for eggs and larvae on the host plant - and possibly adults - we can understand if the population is stable, increasing or decreasing,” he said. “Though the butterfly is uncommon, we do see adults flying in the field frequently.”
When asked about reproduction, Miles said they may be able to answer this better in a year or two. He said they found very few eggs and larvae during the wet season, and they are hoping to locate more during the upcoming dry season.
The butterfly only lays eggs on the Talafalu plant and it is possible that it may also use other plants in the citrus family, although there are currently no records of this occurring.
So are the butterflies helpful or harmful to local plant and animal life? Miles said the butterflies likely help some plants through providing pollination assistance, though this is undocumented for the Samoan Swallowtail. “They are a beautiful and majestic part of the animal life of Tutuila, and this is the only place in the world where you can currently see the Samoan Swallowtail butterfly,” he said.
Approximately 30 butterfly species have been recorded in the Samoan archipelago, with at least 21 species recorded in American Samoa alone.
More information on the Samoan Swallowtail Butterfly Project can be obtained by contacting Adam Miles directly at 633-4456; Mark Schmaedick at the ASCC Land Grant; Tavita Togia at the National Park of American Samoa; and Bob Peck of the USGS.