Nature Today | Bumblebees queens hike hundreds of miles

The discovery means that measures to protect bumblebees may be less effective than biologists thought. Because some bumblebee species even occur in intensive agricultural areas, scientists have until now assumed that those agricultural areas still contain just enough natural area. Now that it appears that bumblebee queens travel great distances, this could mean that bumblebee populations in agricultural areas are largely dying out every year, after which new queens move into the area.

Avid bird watchers

The migratory behavior of bumblebees was noticed by accident by bird watchers who took part in bird counts. Some of them noticed that a lot of bumblebees flew by and so decided to count these buzzing fluff balls. On a peak day, more than eleven thousand bumblebee queens passed a migration site. It is estimated that they flew at a speed of thirty kilometers per hour and could possibly keep it up all day.

“Bumblebees don’t migrate in groups and formations like birds,” emphasizes Fijen. “They make this journey individually.” That also explains why biologists did not notice this phenomenon before. English, French, Swedish and Finnish researchers did, however, count migratory bumblebees in the 1950s and 1970s. In the Netherlands, volunteers registered a total of ten such massive migration days.

Search for new nesting places

Of all bumblebees, only the queens survive the winter. Why they then migrate so massively in the spring is still unknown. Fijen thinks a shortage of nesting places plays a role. If there are not enough such places in nature reserves, they look for new possibilities outside the nature reserve. There they only find agricultural terrain with little biodiversity and little food and nesting places. “But that’s just a hypothesis,” emphasizes Fijen. “Whether that is really the reason remains to be seen from research”.

Conservation measures: more biodiversity

Although exact figures of the number of bumblebees in the Netherlands are lacking, biologists have seen the number of bumblebe species in our country decrease for years. The knowledge of the bumblebee migration means that we have to deal with their protection differently. “If bumblebees do indeed leave nature reserves in search of new places to settle, we have to offer them them,” says Fijen.

It also means that the agricultural areas in the Netherlands do not offer sufficient space for the bumblebees. “At the moment it is a typical case of mopping with the tap open,” says Fijen. The nature reserves produce queen bumblebees, but they disappear again in the agricultural areas. “You cannot solve the problem with more queens in nature reserves. You have to ensure that the population no longer empties in the agricultural area. ”

That is why the biologist argues for more biodiversity, wild flowers and nesting places for bumblebees. Not just in the Netherlands, but on an international scale. An advantage is that the bumblebees can quickly benefit from such new measures. “If we increase the quality and biodiversity of landscapes, they will find their way there, even if it is a hundred kilometers away,” says Fijen.

Reliability and future

Fijen hopes that the new results will lead to more bumblebee counts. Because it is impossible to determine that passing bumblebees on one site are the same as on another, the biologist also wants to track the bumblebees with technology. “Unfortunately, we can’t tie them together,” he says. Scientists can, for example, track insects via radar. Fijen hopes to use such studies to better map the bumblebee migration.

Fijen published his findings in the scientific journal Journal of Applied Ecology. The publication is here to read.