The Bee in Winter

Bumblebee (far) and leafcutter bee (near)

When you think of bees in winter, perhaps you imagine the well-known scene of a colony of non-native honeybees: a boxy wooden hive painted white housing a humming cluster of workers surrounding their queen.

But that is just one strategy;  the many species of native bees found along the Greenway employ a variety of techniques for ensuring their offspring can carry on through our harsh, bitterly cold winter months.

Leafcutter bees (Megachile sp.) build nests in hollows and holes above ground. A female will chew circles out of leaves or petals, which she will carry to her chosen tube and use to line individual chambers. She will provision each chamber with a supply of pollen and nectar, and lay a single egg per chamber. This egg may hatch prior to winter, but the larva remains in the chamber, devouring the pollen and developing into a prepupa, as which it spends the winter before completing its development and emerging as an adult in the summer.

Metallic green sweat bee

Agapostemon sp., including metallic green sweat bees, will normally nest in the ground. The female will excavate a tunnel and lay a single egg in each of several branches within the tunnel. The eggs are laid and hatched within a single summer (sometimes two generations per summer); females will mate at the end of the season and sequester themselves underground, waiting until the following spring to emerge and lay their eggs. Males will, alas, die at the end of the season.

In contrast to these mostly solitary species, bumblebees (Bombus sp.) are social and will form more complex colonies surrounding a single queen. A queen bumblebee will spend the winter underground after mating (again, the unfortunate males will die before winter). When she emerges in the spring she will scout a nest site and provision it with pollen before laying eggs together in a single batch, which she will care for as they develop into a generation of workers.

The queen bumblebee will continue laying eggs throughout the summer, with the earlier generation of workers helping take over foraging and caring for their younger siblings. At the end of the season the queen will lay eggs that will develop into males, who will find and mate with queens from other colonies, and new queens, which will be responsible for overwintering after mating and founding new colonies the following year. When the temperature drops, the remaining workers in the original colony will die, along with the founding queen.

Sources/Resources: 

• The Bees in Your Backyard: A Guide to North America’s Bees by Joseph S. Wilson & Olivia Messinger Carril
• Bees: An Identification and Native Plant Forage Guide by Heather Holm 

Our National Symbol...of Effective Regulations

If anyone tries to tell you that government regulations are unnecessary or ineffective, take them to the Iowa River and remind them of the story of our national symbol.

A bald eagle passing over the Greenway.

Toward the middle of the twentieth century, bald eagles were facing extinction. Their once abundant numbers had been reduced to just a few hundred breeding pairs in the lower 48 states (from an estimated high of several hundred thousand individuals a century earlier). Their decline, like the decline of many species' populations, was the result of a multi-pronged assault. The first, habitat loss, is not unique to eagles, as humans converted (and continue to convert) wild land into cities, suburbs, and agricultural fields. A second reason was deliberate killing of eagles both for sport and to defend livestock (fueled by an exaggerated fear that eagles carry off lambs or even small children). Finally, and perhaps most famously, was the effect of DDT, a pesticide that caused brittle eggshells and made it nearly impossible for birds higher up on the food chain to reproduce.

As our lawmakers and government agencies took note of the eagles' precipitous decline, they took action. Congress passed a series of laws protecting the noble birds from hunting and killing, culminating in their listing as an endangered species by the Interior Secretary in 1967. The pesticide DDT was exposed as extraordinarily harmful to our birds and other wildlife (in part thanks to Rachel Carson's landmark book Silent Spring), and it was essentially banned by the Environmental Protection Agency in 1972. The US Fish & Wildlife Service also implemented captive breeding and reintroduction programs, along with enforcing the laws passed to protect eagles.

With these protections in place, the bald eagle population gradually rebounded and it was de-listed as an endangered species in 2007. Current populations are estimated at around 70,000--healthy, but nowhere near their historic levels.

Thanks to actions and regulations by our government, the bald eagle was saved from near certain extinction in the continental US. This is not something that could be done merely through education and outreach, nor by relying on the goodwill of businesses to do the right thing. It took a concerted effort by our legislators and the federal agencies and departments that are tasked with protecting and preserving our country's resources.

Bald eagles still face threats. Habitat loss will always be an issue. Bald eagles also suffer from lead poisoning at disturbing rates, thought to be caused by lead shot used in dove hunting and other small game hunting (eagles will eat carcasses or gut piles tainted with lead shot, which then accumulates in their system to the point of lethal toxicity*).

The bald eagle is not only a symbol of our nation, but of what our nation can do when we face a problem. Our lawmakers recognized the threat and mustered all hands on deck to defeat it. They are the reason we are today able to enjoy the sight of eagles in trees along the Iowa River and soaring overhead on the Sycamore Greenway.



*It is worth reminding readers that dove hunting was illegal in Iowa for nearly a century, and Iowans were overwhelmingly opposed to it. A bill establishing a dove hunting season was pushed though the legislature in 2011 by means some would consider shady, and later efforts to limit the use of lead shot in dove hunting were overruled. Not that I'm still salty about it or anything.