Wednesday, October 28, 2009

What happens to the polar bears and seals when sea ice melts?

Polar bears and their prey have evolved to living in the extreme conditions of the Arctic. Polar bears and seals are dependent on sea-ice for foraging, resting, and reproduction. The Arctic ecosystem was shaped by climate and continues to be driven today by climate. Polar bears and ice seals, primarily ringed seals, serve as key indicators of the effects of climate change on the Arctic environment. Today, polar bear populations are facing threats previously unprecedented during recorded history in the Arctic. Recent climate change scenarios based upon modeling of climate trend data predict that the Arctic region will experience major changes in the upcoming decades. On the most drastic end of the spectrum one model predicts that the Arctic basin may be void of ice within 50 years. Other models have shown that ice thickness has decreased by 40% during the past 30 years and the average annual extent of ice coverage in the polar region has diminished substantially, with an average annual reduction of over 1 million square kilometers.

While the ultimate or progressively evolving effects of climatic change on polar bear populations is not certain, we do recognize that even minor climate changes could likely have a profound effect on polar bears.

• Climate changes on prey species will have a negative effect on polar bears
o increased snow can result in reduced success in successfully entering seal birth lairs
o decreased snow or increased seasonal rain patterns could effect seal pupping by not providing adequate snow for construction of birth lairs or if rain fall by collapsing birth lairs thus reducing seal productivity
o prey reductions could effect polar bear condition and ultimately cub production and survival

• Changes that alter the period of ice coverage could affect distribution and impact polar bears
o bears may spend greater amounts of time on land
o extended use of terrestrial areas would ultimately effect physical condition of bears when forced to rely on fat stores
o decreased physical condition could effect production and survival
o bears using deteriorating pack ice may experience increased energetic costs associated with movements and swimming

• Denning could be impacted by unusual warm spells
o access to high quality denning areas may be limited or restricted
o use of less desirable denning habitat could have impacts on reproduction and survival
o rain or warming could directly cause snow dens to collapse or be opened to ambient conditions
o loss of thermal insulative properties in opened dens could affect litter survival

Thursday, October 08, 2009

Hummingbird helps researchers to study and monitor air quality

Hummingbirds seem to defy gravity. These tiny fliers can stop in mid-flight, hover, fly backwards, or zip away so fast it appears they simply vanish into thin air, like fairies. To do so, they flap their small but strong, flexible wings at a dizzying rate of 80 beats per second. So fast, that you can hear the characteristic hum of wings cutting through air, but not actually see them move.

The main reason for the hummingbirds' aerial efforts is food. Hummingbirds are nectar specialists, feeding on the sugary, high-energy liquid that plants secrete in their flowers. Hovering gives hummingbirds the ability to efficiently sip nectar where no perches exist. Flying fast between flowers minimizes time between meals, an important factor for an animal that must eat more than one-and-a-half times its weight per day to meet its metabolic demands.

What the researchers find from monitoring hummingbirds will help the EPA's overall efforts to study and monitor air quality. The team plans to build on their initial study this summer by determining the size of the birds' feeding range, which may also be influenced by air quality. Whatever the team discovers in the future may have important implications for human health.