Study of bumblebee decline points to climate ‘vise’

The red-belted bumblebee, shown here visiting a lupine, is among the species shown to be “responding very badly” to climate changes across continents. (Jeremy Kerr photo)

A study of the shrinking range of bumblebee habitat suggests farmers relying on those species to pollinate crops may soon have to look elsewhere, barring a reversal of climate change — or, perhaps, an “assisted migration.”

An international study of specimens from 31 species of bumblebees in North America and 36 such species in Europe, as curated between 1901 and 2010 in museums and labs, finds the bees being slowly forced out of their southernmost habitats by climate change — but unable or somehow unwilling to push further north.

The study, results of which were publicly released Thursday and published in the journal Science, looks into the database of about 423,000 geo-referenced bee observations and finds “rapid declines” in bumblebee species, in “often indistinguishable” patterns, on both continents.

“I’d suspected some (bumblebee species) may be declining, but not such a large proportion,” bee expert, study contributor and York University professor Laurence Packer said in a release. “The fact that at the northern edges of their ranges they are not moving north as the climate changes is actually really quite worrying.”

“For the North American species that I work on, we know that about a third of them are in decline and in some cases this has been quite dramatically, more than 90 per cent,” York University environmental studies professor Sheila Colla said in the same release.

For example, she said, where the rusty-patched bumblebee was the fourth most common species in southern Ontario in the 1970s and early 1980s, she has only seen two in 10 years despite “extensive” searching throughout its range in Canada and the U.S.

“One of the scariest parts of the work that I’ve done is just realizing how quickly the situation is changing,” she said. “The bumblebees that are in decline were doing fine 50 years ago. We’re talking about large changes in community composition of essential pollinators over just a few decades.”

While the study contributors don’t let agricultural pesticides off the hook as a danger to bee health, they emphasized during a conference call that they don’t believe their findings are a result of pesticide use, nor of changes in land use over time.

For example, comparing their data against U.S. data on neonicotinoid pesticide application, the researchers found losses in bumblebee range began before neonics came into wide use.

Rather, lead author Jeremy Kerr of the University of Ottawa said on the call, the study shows a “mechanism operating across two continents to crush bumblebee populations in kind of a ‘climate vise.’

“We’ve lost about 300 km from the ranges of bumblebees in southern Europe and North America,” he said. “The scale and pace of these losses are unprecedented.”

The researchers “don’t know for sure what is causing a stagnation at the northern end” of the habitat range, Paul Galpern of the University of Calgary said in a separate release.

“Bees should be able to start new colonies in places they did not historically occupy. But we don’t know why this is happening so slowly that it looks like the (northern) ranges are not moving at all.”

One theory considers the evolutionary difference between bumblebees and other insects. Many species, such as butterflies, originated and diversified from tropical climates, and thus are more likely to adapt. Bumblebees instead have “unusual evolutionary origins” in the cool-to-temperate Palearctic.

The study also shows its selected bumblebee species shifting to areas of habitat at higher elevation within their usual geographic range.

“Moving upslope doesn’t necessarily mean they’ve lost area there yet,” said study participant Leif Richardson of the University of Vermont, “but eventually, they may simply run out of hill.”

Governments and regulators will need to help manage threats to pollinators generally, and to co-operate internationally to stem the rate of climate change by reducing greenhouse gas emissions, the researchers said.

Also, Kerr said, an “assisted migration” — active intervention to encourage bumblebees to expand their northern ranges — may need to be considered.

The study authors grant the assisted migration idea is “controversial” in conservation biology circles, where it’s already been considered for over a decade, but is “gaining support as warming continues.”

Such a move, Kerr said, must not be attempted without first carefully considering the potential impacts on species already present in those northern reaches.

Galpern, an assistant professor of landscape ecology, said the study shows “an important service to ecosystems” in general under threat.

“Bumblebee species play critical roles as wild pollinators, not just for crops but of all sorts of plants,” he said in a separate release. “They help plants produce fruits, seeds and this in turn provides both food and habitat for other animals, and so on.”

The “very rapid” rates of losses shown on both continents in the study, Kerr said, are “not just something to worry about at some vague future time.”

It’s possible, he said, that to help bumblebees, people and governments “will need to intervene in a significant and expensive way.” — Network


Manitoba's recovery from a 2011 drought, improved potato marketings in New Brunswick and changes in payment timing for Prairie wheat have helped boost farm cash receipts in the first three quarters of this year, Statistics Canada reports. Farm cash receipts for Canadian farmers totalled $39.9 billion between January and September, up 1.9 per cent from the same period in 2012, the agency said in a release Tuesday. This follows an 8.5 per cent gain between the first nine months of 2011 and 2012. Farm cash receipts include market receipts from the sale of crops and livestock, as well as program payments. Cash receipts measure gross revenue for farm businesses and do not represent farms' bottom line, as farmers have to pay their expenses and loans and cover depreciation. Receipts increased in Manitoba (+14.7 per cent), New Brunswick (+11.9 per cent), Newfoundland and Labrador (+6.7 per cent), Alberta (+2.1 per cent), Saskatchewan (+1.7 per cent) and Nova Scotia (+1.2 per cent). Declines ranged from 0.1 per cent in Quebec to 3.3 per cent in British Columbia. Market receipts from the sale of crops and livestock rose 2.5 per cent from the first three quarters of 2012 to $37.9 billion. Crop receipts were up 2.9 per cent to $22.1 billion, while livestock receipts rose 1.9 per cent to $15.8 billion. Wheat (excluding durum) receipts totalled $3.9 billion from January to September, $980 million (+33.5 per cent) higher than the same period in 2012. Both a 25.9 per cent increase in average prices and a six per cent gain in marketings contributed to the strong growth. Conversely, canola receipts declined $715 million (-11.9 per cent) from the same period in 2012, as marketings fell 16.7 per cent. Canola receipts totalled $5.3 billion from January to September. Despite the drop, canola remained the top grossing crop in Canada for the first three quarters of 2013, accounting for 24 per cent of total crop receipts. Crop receipts in Manitoba rose 28.7 per cent, the largest provincial increase, as production returned to more normal levels following the 2011 drought, which had significantly lowered marketings in 2012. Manitoba wheat (excluding durum) receipts rose $348 million (+86.2 per cent) as marketings were up 65.1 per cent and prices rose 12.8 per cent. Gains in soybean, canola and corn receipts, mainly as a result of increased marketings, also contributed to the rise in Manitoba crop receipts. New Brunswick also had strong growth in crop receipts (+27.4 per cent), as potato marketings increased 46.7 per cent from January to September compared with the same period in 2012. Potato production in New Brunswick rose to more normal levels in 2012, following a lower than average 2011 crop. In contrast, Prince Edward Island (-8.5 per cent) had the largest percentage provincial drop, as potato receipts fell 10.2 per cent because of declining prices and marketings. Poultry, hog receipts up Nationally, on the livestock side, receipts gains were seen in the poultry and hog sectors for the first nine months of 2013. Total chicken and turkey receipts were up $156 million (+7.8 per cent), as both marketings and prices rose. Hog receipts were up $128 million (+4.4 per cent) compared with January to September 2012 levels, despite marketings declines, as prices rose six per cent. Lower cattle and calf receipts (-0.9 per cent) moderated the increase in total livestock receipts, as the total number of head marketed was down 1.5 per cent from the same nine-month period in 2012. A 37.6 per cent rise in the number of cattle and calves exported internationally was not enough to offset declines in both the number of head exported interprovincially (-12 per cent) and slaughtered domestically (-6.9 per cent). Egg receipts totalled $698 million (+8.4 per cent) from January to September, mainly because of a 6.8 per cent rise in average prices. Dairy receipts were flat as a 1.5 per cent price increase was offset by declines in marketings. Total farm cash receipts for the supply-managed sectors (dairy, poultry, and eggs) reached $7.3 billion from January to September, up three per cent from the same period in 2012. Program payments amounted to $2 billion in the first three quarters of 2013, 9.4 per cent below the same period in 2012. Increases in crop insurance payments (+27.7 per cent) were not enough to offset declines in AgriStability (-35.4 per cent) and Agri-Invest (-16.8 per cent) payments. Wheat payments Some of the increase in wheat and barley receipts for the 2012-13 crop year (August 2012 to July 2013) can be attributed to changes resulting from the Marketing Freedom for Grain Farmers Act, Statistics Canada noted. Under the provisions of the Act, Prairie producers have the ability to market their wheat and barley (destined for export or domestic human consumption) on the open market, receiving payment at the time of delivery, or, voluntarily through the former Canadian Wheat Board (CWB). Under the CWB pool system, producers receive a partial or an initial payment at the time of sale. As the marketing of the crop progresses, adjustment and final payments are made. The expansion of marketing options available to producers has resulted in a change in the timing of when some producers are being paid. As farm cash receipts are estimated on a cash basis -- that is, when payment is received -- this change has an impact on the data, Statistics Canada said. Farm cash receipts data for the fourth quarter of 2013 and the first quarter of 2014 will be released in May 2014. -- Statistics Canada release  


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Dave Bedard

Editor, Daily News, Glacier FarmMedia Network. A Saskatchewan transplant in Winnipeg.


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