13
Jul
Study Links Climate Change to Shrinking Bumblebee Habitats
(Beyond Pesticides, July 13, 2015) Many factors have been identified in bee and other pollinator decline across the globe, including loss of habitat, disease, and pesticides. A new study from researchers in North American and Europe finds that the changing climate also plays a vital role in decreasing bee habitat and thus reducing populations. The study reports that North American and European bumble bees are unable to colonize new warmer habitats north of their historic range, while simultaneously disappearing from the southern portions of their range.
Published in Science, the study, Climate change impacts on bumblebees converge across continents, which is a comprehensive look at 67 bumblebee species and their territories over the last century, finds that many North American and European bumblebees have retreated from the southern edge of their historic ranges (away from the equator). While other species of animals have been able to adapt to climate change by expanding their habitats, bumblebees have not shifted to warming northern climes and are experiencing shrinking distributions in the southern ends of their range. The rusty patched bumblebee (Bombus affinis), for instance, has disappeared from parts of the southeastern U.S.
Bumblebees are also retreating to higher elevations, shifting upward by an average of about 300 meters over the same time period. This means the habitat ranges for bumblebees have overall compressed, as no gains are being made northward. According to the study, bumblebees have lost more than 180 miles of their southern range in both continents over the past 110 years. The researchers believe that this phenomenon suggests an elevated susceptibility to rapid climate change, since bumblebees having evolved in mild, temperate climates, will find it difficult to survive in increasing warmer conditions in their historic habitats.
“Climate change is crushing [bumblebee] species in a vice,” says ecologist Jeremy Kerr, PhD, of the University of Ottawa in Canada, the study’s lead author.
The researchers are not sure why bumble bees have not been able to expand their northern ranges. According to Dr. Kerr, there are two reasons a species might not shift well in response to climate change: Either it has problems actually moving from one place to another, or it has problems building up its population once it gets to a new place. “Clearly bumblebees are pretty good at getting around,” Dr. Kerr said at a press conference, since they can fly. Rather, the scientists suspect that they are having trouble growing their populations at their northern range limits. However, the reason remains unclear.
This new study is not good news for bees. Bumblebees, like honey bees and other bee species are facing unprecedented population declines in recent years. In addition to challenges from global climate change and habitat losses from expanding urban and agricultural regions which eliminate native forage for bees, they also face the added survival burden from toxic pesticide exposures. Pesticides, like the neonicotinoids, have been identified as a major culprit in bee decline. These pesticides are associated with decreased learning, foraging and navigational ability, as well as increased vulnerability to pathogens and parasites as a result of suppressed bee immune systems. Used widely in agriculture as seed treatment for various crops, foraging bees, in the absence of their native habitat, are exposed to fields of poison where even pollen and nectar are contaminated. In addition to toxicity to bees, pesticides like the neonicotinoids have been shown to also impact birds, aquatic organisms and contaminate soil and waterways, and overall biodiversity. For more information read our piece, Birds, Bees and Beneficials.
While climate change is a challenge to every plant and animal species on our planet will have to gradually adapt to in coming years, including changing or disappearing habitats and greater temperature fluctuations, various environmental factors are influencing the crisis faced by bees and other pollinators. However, we can take action on bee-toxic pesticides and eliminate one of the major risks posed to bees now!
The U.S. Environmental Protection Agency (EPA), which oversees pesticide use in the U.S., has consistently fallen short in its efforts to mitigate these harmful effects to bees and other pollinators. In May 2015, EPA released a proposal intended to create “physical and temporal space” between bees and toxic pesticides. They call these spaces “temporary pesticide-free zones,” which has been called misleading by environmentalists. While touted as monumental progress on bee health by the agency, the reality is that the proposed minor label change will not stop the widespread contamination of landscapes or prevent harm associated with neonicotinoids.
In light of the shortcomings of federal action to protect these beneficial creatures, it is left up to us to ensure that we provide safe havens for pollinators by creating pesticide-free habitat and educating others to do the same. Take action by calling on EPA to suspend neonics now. You can also declare your garden, yard, park or other space as pesticide-free and pollinator friendly. It does not matter how large or small your pledge is, as long as you contribute to the creation of safe pollinator habitat. Sign the pledge today! Need ideas on creating the perfect pollinator habitat? The Bee Protective Habitat Guide can tell you which native plants are right for your region. For more information on what you can do, visit our BEE Protective page.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: Science , Washington Post
Photo Source: Layla B, England
