Amateur Naturalist: Bumble Bee Decline
A variety of plants bloom in the spring but their flowers fade by mid summer. There is an exception. Russian sage blooms throughout the summer. Its branches become completely covered with hundreds of small blue flowers. “Summer Blue bush” would be a good alternative name.
Russian sage is a major source of nectar for bees. Different kinds of bees begin to appear shortly after sunrise. Bumblebees are more adapted to cooler temperatures and so are among the first to arrive in the early morning. Honey bees then appear. A bush may have a dozen bees on it at one time, all looking for nectar. “Humming bee bush” would be another good name.
Bees may provide an indicator of the impact of global climate change. The Western bumble bee was once common in western North America, but this species has become increasingly rare throughout much of its range. Mathematical ecological modals show declines from 15% to 83% across 16 ecological regions. These mathematical models include how extensively pesticides are used in agriculture and the type of farming that is occurring.
The American bumble bee is following a similar trend. As many as 50% have disappeared from the Midwest and Southeast. As many as 99% have disappeared in New York state. They have vanished entirely in eight other states.
But these distinct downward trends do not apply to all species of bumble bees. The Hunt’s bumble bee has had some decease in abundance over the past century but does not have a clear downward trend. It is placed in the “least concern” category in one report.
Seven local Russian sage bushes were assessed for bees. Six of the seven bushes had Hunt’s bumblebees on them, looking for nectar. Honey bees also appeared on the bushes. Perhaps the higher mountain elevation makes the climate cooler and so more supportive of Hunt’s bumblebees. But what is happening at lower elevation areas such that the Hunt’s bumblebee has not declined like the Western and American bumblebees?
Understanding the interrelationship between global climate change and bee populations is important. Bees work from dawn to dusk, carrying pollen from flower to flower as they look for nectar. The pollinated flowers will produce fruits and vegetables later in the summer and the seeds for new growth next year. Imagine if bees were no longer available to pollinate. Then imagine if grocery stores had very limited or no fruits or vegetables available.
A Russian Sage covered with flowers. Russian sage bloom throughout the summer and its branches become completely covered with hundreds of small blue flowers. Photo by Robert Dryja
Hunt’s Bumblebee: White bands can be seen on each side of an orange band on the bee’s rear abdomen. The Hunt’s bumble bee has had some decease in abundance over the past century but does not have a clear downward trend. It is placed in the ‘least concern’ category in one report. Photo by Robert Dryja
