Walking Among Giants in Northwest Thailand
This post is the first in the “Travel Bug” series by Laura Kraft, a recent graduate from the University of Georgia, who will be chronicling her travels in Asia from an entomological perspective.
“This is my office,” Dr. Robinson says jokingly, slinging his backpack onto his back and mounting his bike with a gesture of familiarity. We take off in the sticky heat of the morning, leaving the charming mountain town of Mae Hong Son in northern Thailand and heading for Dr. Robinson’s field research site at the Mae Hong Son Agricultural Research and Development Centre along the Pai River.
I traveled to this secluded provincial capital, just west of the tourist hub of Pai, to meet Dr. Robinson and try to see his study organism, the giant honey bee, Apis dorsata. Dr. Robinson first became interested in honey bees during a beekeeping course in his undergraduate studies at Cornell. He later pursued a master’s at Washington State University and then a Ph.D. under Roger A. Morse at Cornell, both focusing on honey bees. After his Ph.D., Dr. Robinson ended up Wyoming, where his wife Maria is from, teaching at a local community college, Casper College.
Dr. Robinson enjoys teaching and has led several study abroad trips to Kenya, Costa Rica, and Ecuador. During his time teaching, Casper College decided to make the Mae Hong Son Community College their sister college. Dr. Robinson had a sabbatical coming up and jumped at the chance to visit the sister college and study native Asian bees in Thailand.
When Dr. Robinson first arrived, he expected to study the Asian dwarf bee, Apis florea, though he found only one small colony that was quickly ransacked by hornets before he could study it. Then, by chance, Dr. Robinson stumbled across two thrumming masses of A. dorsata hanging on a mango tree while biking through the Agricultural Research and Development Centre along the Pai River. At first, he thought the larger of the two was a colony and that the smaller had split off and was swarming, but then a strong breeze passed through the valley and the colonies started waving back and forth on the branches. He realized he had found two migrating colonies of A. dorsata — the first time anyone had found an annual migration stopover site for this species.
The giant honey bee host range stretches from Pakistan to Indonesia. This honey bee is known for some incredible migrations, including one across the Malacca straight between Indonesian Sumatra and peninsular Malaysia. While migrating, the bees stop periodically to rest in trees, forming combless bivouacs. During these periods, the bees will collect food reserves at the bivouac sites.
Such a site resides a few miles outside Mae Hong Son. It is a narrow strip of orchard space and agricultural land stretching north-south along the Pai River. You can hear the excitement in Dr. Robinson’s voice as he describes the bees that he first found. He came back daily to ride slowly up and down the transect, tagging branches with new bivouacs, even seeing some swarms arrive, during the late part of the monsoon season in Thailand, from August to early November.
Dr. Robinson then received some funds and permission from Casper College to return again in 2010 to continue studying what was to be the first discovery of an annual migration stopover of giant honey bees and to try to understand what conditions were attracting the giant honey bees to the site as well as where they might be traveling. Some trends soon became apparent. The bees showed a preference for mango trees, and to a lesser extent the macadamia trees, though they did not bivouac in pomelo trees. The bivouacs would also find harbor in some other native tree species, including teak and cluster fig.
Despite its small size, the site provided shelter for 52 A. dorsata bivouacs over the two-year study period. The bivouacs ranged from the size of a Ping Pong ball hanging under a mango leaf to the size of an adult human, spanning an entire branch.
Like other species of honey bees, the giant honey bee communicates through dance. Dr. Robinson recorded the angle and length of these dances to determine where the bees may be headed but found that they were flying in different directions, likely migrating to nesting sites at a higher elevation where more shade and water could be found during the upcoming dry season.
There are a few hypotheses as to why the site is so attractive to bees migrating annually. Annual migration stopovers probably have physical landmarks that make them easily recognizable to giant honey bees, and they likely also have flowering plants to provide food. The Agricultural Research and Development Centre has flowering teak as well as non-native eucalyptus trees bordering the orchard site that are in bloom during the late monsoon season when the stopover occurs. Dr. Robinson also hypothesizes that the density and shade provided by the mango trees, as well as their bark pattern, may be appealing to bivouacs, in comparison to the heavily pruned, open canopies and smoother bark pattern of the unattractive pomelos nearby. Even details like branch angle and distance from a water source, the river, may have significant impact on bivouac sites, which are limited to a small area of the transect. (The mango orchard attracting most bivouacs is now approximately 270 x 30 m due to a recent removal of several trees as part of a small construction project.)
The discovery of annual migration stopovers of A. dorsata is important for many reasons. Honey bees are important for pollination of agricultural crops as well as native flowers. The giant honey bee and other native Apis species are also valued for their honey and wax in southeast Asia, besides being an important part of local culture. While declining nest sites are receiving attention of conservationists, it is vital that these migration stopovers receive more study and conservation research and work to protect the declining species.
As for me, I had arrived at the field site one day too late and missed the last bivouac of the season, but I learned a lot about the bees and conservation. Seeing just how small the area is where the bees prefer to bivouac year after year brings home how fragile these stopover sites are and how desperately they need our attention to conserve native Asian honey bees.
Photo captions: Dr. Will Robinson pointing at a bivouac of giant honey bees, photo courtesy of Maria Katherman; Will Robinson biking to the Mae Hong Son Agricultural Research and Development Centre, photo courtesy of Laura Kraft.