 |
| Close-up of Polar Bear's face |
Polar bears, also known as Ursus maritimus, evolved about 200,00 years ago from their brown bear ancestors.
Diet: Ringed and bearded seals are the main source of food for polar bears (Amstrup 2003). Occasionally they may also eat harp, hooded seals, walruses, narwhals, bowhead whales, and beluga whales (World Wildlife Fund WWF). When these food sources are not available, polar bears eat pretty much any mammal or vegetation they can find. For these reasons, polar bears are also known as the world’s largest land predators and are usually on the top of the food chain.
 |
| Polar bear with dead seal |
Habitat: Polar bears are usually found on Artic sea ice, water, islands, and the coastlines of the major continents. They prefer sea ice habits which with leads, which are stretches of open water in between ice fields that allow polar bears to hunt for prey like seals (Sterling and Guravich 1998 ). Polar bears spend majority of their life on sea ice in a sense making them like a marine mammal. Polar bears depend on ice for breeding, movement, and catching prey (Hunter et al 2010). However, female polar bears usually have their maturity dens along the coastlines of continents on snowdrifts which are on land (Sterling and Guravich 1999).
 |
| Picture (left): Polar bears on ice. Picture (right): Mother polar bear with two cubs. |
Characteristics: A typical adult male polar bear usually weighs from 770 to 1500 pounds (Derych 2011). The average adult height for male polar bears can be up to 8.5 feet, or approximately 2.6 meters. Females, on the other hand normally weigh anywhere from 330 to 720 pounds (Derych 2011). Their average adult height can be up to 6.5 feet, or about 2 meters. Polar bears also have an undercoat which acts as an insulator to keep them warm. This undercoat is topped off with hairs known as guard hairs (Polar Bear International). These hairs are pigment-free and transparent in appearance. Interestingly, polar bears look the “whitest” when they are clean and in sunlight because their hairs reflect visible light (Polar Bear International).
Life Span and Reproduction: In the wild, polar bears’ lifespan can range from 15 to 18 years. However, biologists have found some polar in the wild that were in their 30’s. Females can begin to mate when they are 5 years old and usually mate between the months of April and June (Hunter et al 2007). When females get pregnant, they dig a den in the snow and enter their maternal dens until the cubs are born. Females generally give birth from December to January and they nurse their cubs until they are old enough to leave the den which is usually the following March and April (Hunter at al 2009). In addition, the cubs usually generally stay with their mother until they are about two years old.
Current Status: Polar bears were listed as threatened in 2008 under the ESA (Feldman 2008).
6 comments:
Polar bears, also known as Ursus maritimus, evolved about 200,00 years ago from their brown bear ancestors.
Polar bears can be found in areas such as the United States, Canada, Greenland, Russia, and Norway where they are well-suited to snow and ice. Their main source of food are ringed seals which they usually hunt for in sea ice openings known as leads. However, they may also eat other mammals, eggs, and vegetation if required. Polar bears are also known as the world’s largest land predators and are usually on the top of the food chain.
A typical adult male polar bear usually weighs from 775 to 1200 pounds. Although there some males that weight more than 1200, this is quite uncommon. The average adult height for male polar bears can be up to 8.5 feet, or approximately 2.6 meters. Females, on the other hand normal wright anywhere from 330 to 650 pounds and their average adult height can be up to 6.5 feet, or about 2 meters.
Polar bears usually spend their entire life on pack ice. Although females prefer ice along the shorelines, other bears prefer moving sea ice at the floe edge-usually within 180 miles of shore.
Your information is laid out well and flows easily from page to page. There are some grammatical/spelling errors that can be easily fixed by proofreading. I think you should also include some numbers to show the severity of the problem (i.e. how small has the population become? how much of their habitat has been destroyed? is it becoming more dramatic each year?). You could also add a section on how people can help. How would we go about slowing down global warming or restoring polar bear habitat? Is there anything being done already? You also don't have a synthesis graphic on your blog yet. (I had a hard time thinking of one, too) One suggestion would be to create a graph to show how efforts to restore habitat has or hasn't helped over time. Overall, this is a pretty informative blog. Good job!
-Natalie Rogers
Great website layout! I really like the color scheme. I noticed the text font and color changed from page to page. It might be a good idea, for consistency, to stick with one. I didn't see a synthesis graph on your website. I really like the mercury bioaccumulation page. Maybe you could diagram the bioaccumulation of mercury for your synthesis graph? Overall, great job so far!
Here's a link I found to a diagram in which the top predator is a human. You could play with it and possibly make it into a polar bear.
http://people.uwec.edu/piercech/Hg/Pictures/merccycle.jpg
I would also look into citing your pictures and adding a few references throughout your web pages. You can add a caption to your picture by clicking on the picture and selecting the "caption" option.
Your blog is good. However, it is possible to add more picture/graph/figures/table to make your website look better. I would add captions to the pictures. Also, I feel like an addition "How do we help?" page would be great!
~Khoi Le
Post a Comment