The mass-migrating flight of the bumble bee
Thijs Fijen is, by his own admission, a fanatic birdwatcher. For years he has been visiting various sites in the Netherlands – heathlands, dunes, dikes, forest edges – to observe and count migrating birds. During those visits, well before he became a pollinator researcher at Wageningen University, Fijen and other observers would also count the bumble bees that passed through the Dutch countryside.
“We always noted down the bumblebees,” he explains, “but just because it was the protocol for that site.” And all of that incidental bumble bee data was then entered into Trektellen.org, an open-access database of bird migration, along with the primary counts of birds.
Over the years, Fijen heard other observers talk about the bumble bees. Not just as single specimens of interest, but as mass migration events. In 2018, he got to witness one such event.
“It is incredible,” says Fijen. Hours of bumble bees buzzing through the air in a constant stream, in one predominant direction. “You can see individuals approximately up to 400 meters on both sides, and about 200 meters above you.”
Fijen started asking other pollinator researchers about these apparent migrations, but no one seemed to know anything. “At this time I knew I had to look further into this,” he says.
Fijen’s curiosity and research has culminated in a new paper describing what we currently know about this phenomenon of mass-migrating bumble bees. Which is not a tremendous amount, to be sure. But these migrations haven’t gone completed undocumented in the scientific literature. One of the earliest observations, by Dr. Neville L. Birkett in the United Kingdom, appeared in a 1956 issue of the Entomologists Monthly Magazine:
“On May 28th this year I visited the West Cumberland coast near the village of Silecroft. Between 2 p.m. and 6 p.m., B.S.T, a remarkable and persistent flight of Bombus lucorum L. was observed... On an average some three or four specimens per minute passed during the time of observation, most of them seemed to be females and those caught for identification proved to be Bombus lucorum L.”
The Trektellen bumble bee data provides an even more detailed picture of these migrations. The database contains a lifetime total of 65,439 migrating bumble bees from all its observation sites, with eleven sites recording more than 1,000 migrating bees in a single day – all of them occurring during the European spring time. The largest recorded event tallied 11,142 bees over an eight hour period; the vast majority of this count happened in just the last three hours, averaging about 60 bumble bees per minute passing through the site.
Little to no collection has been done during these counts, and it can be particularly hard to accurately identify bees on the wing and at a distance. However, Fijen is confident the bees in these migrations are queens. “The size of the individuals indicate that they are queens,” he says. “In addition, workers are not reproductive, and have nothing to gain by migrating. Males are not present in this time of year, they are only produced in late summer.”
Obviously, there’s plenty more for us to learn about these migrations. Some of the essential questions include: Why do bumble bees migrate? Where are they coming from and where are they going to? What factors (such as weather) determine the scale or timing of these migrations? How many different species migrate? What impact could these migrations have on bumble bee conservation?
Additionally, almost all of the documentation we currently have comes from Europe. We do not, for example, appear to have any documentation of bumble bee migrations in North America.
So if one were inclined to start looking for such events in the United States and Canada, where might be the best places to do that?
“I would start with looking at the spots where spring bird migration is massive, or on the spots where Monarch Butterflies show concentrated migration,” Fijen suggests. “This will usually be bottleneck land features or along coasts of large lakes or ocean.” Although he’s not familiar with the phenology or climate of North America, Fijen also recommends looking in areas where spring temperatures are markedly different from winter temperatures – because, presumably, any queens in those areas will likely emerge at more or less the same time.
On his own side of the Atlantic, Fijen plans to continue documenting as many migrations as possible, to improve our understanding of where and when these events are happening. But he’d also like to do some isotope analyses of migrating bees to determine their points of origin and, by extension, how far they've traveled.
It will be interesting to see just how common these migrations are for one of our most commonly-studied pollinators.
Conservation
Entomologists eradicate first Asian giant hornet nest
(Washington State Department of Agriculture) WSDA entomologists successfully eradicated an Asian giant hornet nest by vacuuming the hornets out of the nest on Oct. 24, just two days after finding the nest in a tree on private property in Blaine, Wash. In all, the entomologists with WSDA’s Pest Program removed 98 worker hornets. During the early morning extraction, 85 hornets were vacuumed out of the nest and another 13 live hornets were collected with a net while observing the nest.
Working landscapes need at least 20% native habitat
(Twitter, Lynn Dicks @LynnDicks) “One way to ensure that nature thrives in farmland and planted forests is to protect patches of natural habitat throughout. We argue that working landscapes need at least 20% native habitat to preserve” The original paper.
Policy/Law
California extends public comment period for neonic mitigation to Oct. 30
(California Department of Pesticide Regulation) The California DPR has extended the comment period to October 30, 2020, in order to provide more time to gather feedback from the public on the proposed pollinator protection mitigation measures for the use of nitroguanidine-substituted neonicotinoids in agricultural crops. Comments and feedback can be made by email to neonics@cdpr.ca.gov or by leaving a voicemail message at 916-445-0003.
Science
The effects of environmental toxicants on the health of bumblebees and their microbiomes
(Twitter, McArt Lab @McArtLab) “Very cool. Great new paper linking environmental toxicology to bee microbiomes”. The original paper.
Shifts in flowering phases of plants due to reduced insect density
(ScienceDaily, Friedrich-Schiller-Universitaet Jena) A research group has discovered that insects have a decisive influence on the biodiversity and flowering phases of plants. If there is a lack of insects where the plants are growing, their flowering behavior changes. This can result in the lifecycles of the insects and the flowering periods of the plants no longer coinciding. If the insects seek nectar, some plants will no longer be pollinated.
Society/Culture
The importance of words: revising the social insect lexicon
(Twitter, Elva Robinson @Elva_Robinson) “I recommend other social insect lab groups also discuss this paper about the culturally and racially-loaded words we use to talk about social insects.” The original paper.
Technology
Combplex wins $500,000 to save the bees
(Ithaca.com) Varroa mites have been listed by the USDA as the number one stressor to bee colonies, contributing to the loss of 42% of all colonies of five or more. The Complex team believes their new technology can drive those numbers down. They’ve described their process of removing the parasitic insects is like “laser hair removal gone slightly wrong” for bees. And Combplex recently finished the 2020 NYSERDA 76West Competition as finalists, securing $500,000 for their business venture.
One More Thing…
Luminar Bug Photography Awards 2020
“In its inaugural year, the Luminar Bug Photography Awards have attracted an astonishing variety and quality of work from around the world. Over 800 photographers made submissions, all competing for the prestige of winning, and a prize fund of over £23,000.” See all the 2020 winners.