A new study suggests the decline of bumblebee species especially in North America and Europe are due to increasing climatic changes since the 70’s.
A recent study published on Thursday declares Bumblebees are losing their sense of direction due to climate changes. According to the study losing their sense of direction leads to a decrease in the number of bumblebee populations found in regions such as Europe and North America. The increase in temperatures in recent decades has led to decrease in bumblebee populations.
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Bumblebees have been retreating from the south by 190 miles since the 1970’s. Climate change has narrowed the range where bumblebees are found in North America and Europe in recent decades, according to a study published Thursday.
The paper was published in the journal Science and the lead researchers believe the northern habitats are becoming less hospitable to the bumblebees. As the decrease of Bumblebees in the southern areas should have seen an increase in Bumblebee populations of the north, however that is not the case.
The research was carried out at the University of Ottawa in Canada and one of the lead researchers was a conservation biologist, Jeremy T. Kerr. According to Kerr ‘Bumblebee species across Europe and North America are declining at continental scales’ and their findings suggest the climatic changes are to be held responsible.
‘Climate change is crushing [bumblebee] species in a vice,’ said Dr. Kerr. Kerr shared his thoughts during a press conference and stressed climatic changes are the main reason for bumblebee population decrease saying ‘our data suggest that climate change plays a leading, or perhaps the leading, role in this trend.’
Another co-author Paul Galpern, from the University of Calgary said ‘One of the most striking results was that trends were often indistinguishable between Europe and North America.’ Galpern a landscape ecologist himself stated ‘Bumblebee species are responding quite similarly across continents since climate change began to really accelerate from 1975.”
The study was carried out by observing more than 420,000 Bumblebees of 67 different species found in areas such as North America and Europe. An extensive database was then constructed using the observations and it included data such as where and when the bumblebees were found along with their travel habits.
Museum records going back to 110 years were also taken into account for the database. Therefore the research data includes bumblebee population statistics along with climatic change data from the 1900’s till 2010. From the database the researchers drew the conclusions that the bumblebees have shifted their travelling habits in the northern and southern hemispheres in the last century.
The paper also shed light on the issue of using pesticides on bees such as the neonicotinoids, which have caused bees to lose their fluster and forget their positions. Although Bumblebee conservationists argue using pesticides have caused huge losses in bumblebee populations, the paper argues climate changes are more of a culprit than the pesticides.
A co-author and a postdoctoral fellow Alana Pindar from the University of Guelph stated “The question is, have neonicotinoids or habitat losses caused the huge range losses we observed in this study? The answer for now is clearly ‘No.’”
Especially changes in bumblebee populations from 1974 were observed when the climatic changes started getting drastically warm, due to human causes. The co-researcher Leif Richardson, who is an ecologist at the University of Vermont, found the bumblebee species from the south having been going to the north at an alarming rate of 3 miles every year.
For example the bumblebee species Bombus affinis, once found in Georgia can rarely be seen in Illinois or Wisconsin. While the species Bombus terricola of the northern regions such as North Carolina is only found in some parts of Maine. Dr. Leif said "The bees are losing range on their southern margin and failing to pick up territory at the northern margin - so their habitat range is shrinking."
Although the study makes strong arguments the paper hasn’t been universally accepted with some entomologists saying the findings only suggest a correlation between temperature increase of the climate and bumblebee population ranges. Critics argue there is no substantial proof of the relationship between bumblebees and climate and increase in temperature may be one of the causes for their dispersion but not the main and only cause.
Entomology researchers such as Dr. Sydney Cameron who specializes in bumblebee conservation from the University of Illinois especially disputed the findings. Dr. Cameron called the study noteworthy due to the extensive database, but also pointed out the few shortfalls.
“They are concluding the future is dire and that bumblebees won’t move north,” Dr. Cameron said. It’s correlative, not causal; they cannot say that a two-degree climate change caused these patterns.’
An entomologist from the department of Agriculture James Strange also criticized the paper saying, “What they’ve shown is that climate change has at least some effects on the population changes of some bumblebee species. But I did not come away convinced that climate change is causing these movements.”
Dr. Strange also shared his view that people might be misguided by the paper and believe climate change is the only cause of bumblebee population dispersal. Dr. Strange said ‘There’s a bit of me that’s nervous someone will pick this up and say ‘They figured it out: It’s climate change. But really, we haven’t figured it out yet.’
On the other hand a bee biologist at the University of Sussex, Dave Goulson stated he is not surprised by the findings of the study. Although Goulson was not part of the study, he emailed the authors and stated the bees thriving in cooler climates are mainly affected by the climate changes in the southern areas.
Goulson also stated “What is more surprising is that they do not seem to be expanding northwards. Perhaps because suitable habitat is not available to the north of their existing ranges.”
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Goulson also credited the study as being the first evidence in the form of a research paper which shows bumblebee populations are decreasing across large geographical areas.