Polar Bear
- ursus maritimus -
labeled : VULNERABLE
Cassidy Bingham
bio 227-01
fall 2016
Cassidy Bingham
Description and Ecology :
The Polar Bear was listed as threatened under the Endangered Species Act in May 2008; largely due to the loss of sea ice. The Polar Bear evolved from the Grizzly Bear over 250,000 years ago. They are actually considered the largest species of bear in the world. Adult males weigh 300 to 800 kg and measure 200 to 285 cm in length from tip of nose to tip of tail, while adult females weigh 150 to 400 kg and measure about 180 to 247 cm (DeMaster and Stirling 1981, Amstrup 2003).1 A polar bear can live up to 20 years.
Polar Bears are carnivores and are considered one of the top
predators in the arctic; mostly consuming ringed seals (Phoca hispida) and bearded seals (Erignathus barbatus).
A male polar bear reaches sexual maturity around 5, but has a lot of competition with prime older specimens >10. Females are mature between 3-6. Polar Bears are pregnant between 195-265 days.Polar Bears are considered a large species. Their reproductive rates are quite slow for a variety of reasons laid out in the U.S fish and wildlife services including:
- Each of their litters are quite small
- They reach sexual maturity quite late
- They raise their children for extensive
amounts of time before they can go
out on their own.
- cub mortality rate is high in the first
year due to the mother’s condition
during gestation. The fattier the mother,
the bigger the cubs; which gives it a better
chance of survival.
According to the U.S Fish and Wildlife Services2, the Polar Bear is often called different names among locals in its native arctic territory. Some of the names include nanook, and sea bear.
Geographic and Population Changes:
According to the U.S Fish and Wildlife Service’s Conservation Management Plan, the current Polar Bear population rests around 20,000-25,000. They span across 5 different Arctic geographies. The most common location to find a polar bear is the annual ice over the continental shelf.
- Polar Bears that have continuous access to sea ice are able to hunt
throughout the year.
- However, in those areas where the sea ice melts completely each summer,
Polar Bears are forced to spend several months on land, where they primarily fast on stored fat reserves until freeze-up.
Main Threats to its Continued Existence:
The biggest threat that the Polar Bear faces is the melting of their habitat due to global climate change. So in part, humans are actually the culprit of the polar bear decline. The rapid melting of the ice caps is caused by increasing emittance of greenhouse gasses. If there is a chance of recovering the lost polar bear population, it has to start with greenhouse gas reduction legislation. The Polar Bear is the main predator in an extreme climate, and the entire ecosystem now hangs in the balance thanks to human over-consumption. The extreme conditions such as the arctic are the first to be affected by climate change, so they will be the first wiped out if we do not make a change.
Recovery Plan:
According to the U.S Fish and Wildlife’s Conservation plan there are seven major strategies that will be implemented to rescue the Polar Bear populations.
- decrease global atmospheric levels of greenhouse gases
- support international conservation efforts through the range-states relationship.
- keep track and minimize human - bear conflicts
- work together to manage subsistence harvest
- protect denning habitats
- minimize contamination from oil spills
- continue to conduct research and monitoring
What can we do?3
-- vote for representatives that understand the importance of reducing the carbon footprint
- use public transportation or try to reduce the carbon emission
- use energy-efficient technology and building methods
- minimize consumption: reduce, reuse, recycle
Resources Used if you want to learn more:
1. NatureServe Explorer : http://explorer.natureserve.org/servlet/NatureServe?searchName=Ursus+maritimus
2. U.S. Fish and Wildlife Service: http://ecos.fws.gov/ecp0/profile/speciesProfile?spcode=A0IJ#lifeHistory
3. Conservation Management Plan:
http://ecos.fws.gov/docs/recovery_plan/Polar%20Bear%20Conservation%20Mgmt%20Plan.pdf
4. IUCN Redlist of threatened species
5. Polar Bears International
6. World Wildlife Foundation
7. Defenders of Wildlife
Polar Bears are carnivores and are considered one of the top
- Each of their litters are quite small
- Polar Bears that have continuous access to sea ice are able to hunt throughout the year.
Polar Bears are forced to spend several months on land, where they primarily fast on stored fat reserves until freeze-up.
6. World Wildlife Foundation
7. Defenders of Wildlife
No comments:
Post a Comment