Warming Affecting Polar Bears.
Climate change causes unidirectional changes within the annual
patterns of sea ice distribution, structure and freeze-up (Stirling and
Derocher 2012). Climate change has caused some species to become extinct,
especially those who are living within polar and mountain top species (Parmesan
animals that are living on the land such as polar bears, are in much more
danger with the ice melting than animals that live within the sea such as the
humpback whale, they aren’t affected as much as they aren’t reliant on having
the ice to travel on (Huntington and Moore 2008). As many
know, polar bears live in ice covered waters and due to global warming, these
areas are being affected (Parkinson and Stirling
2006) but polar bears are very reliant on this ice for many things (Amstrup et
al. 2010). The ice is melting and it is causing a loss of habitat for
the polar bears, and affecting the ice associated seals (Born et al. 2008). It also means it is harder for the
polar bears to hunt for seals (Stirling et al 2004, Prop
et al. 2015) which are the main food that the polar bears consume (Iverson et al. 2013). Due to all of the climate
change and global warming that is happening, it is unlikely that the polar
bears will survive if the ice continues to melt and will eventually be left
with just water (Stirling et al 2004), it is actually predicted by 2050 the
polar bear population will have declined a significant amount (Lorenzoni et al. 2008). The polar bears are already
suffering a great amount within the summer as all the ice is melted and they
are forced to fast for at least 4 months of the year (Stirling
and Derocher 1993), and then having to deal with the climate changing
within the cooler months as well is making life very difficult for the polar
Polar bears will not only use the ice in order to access food but
it is also so they are able to travel and mate (Ramsay and Stirling, 1986; Stirling et al., 1993).
Due to there being more open waters, the polar bears will still need to travel
to places but they will have to walk or swim longer distances in order to get
to there desired location which is then more energetically expensive for the
polar bears (Mauritzen, et al 2003). Due to there
being a decreased availability for food and then movements becoming more
energetically expensive, it will cause poorer body condition within the species
(Stirling and Derocher 1993). In order for the polar bears to reproduce they
need to have an adequate body condition, to produce the offspring (Rode et al.
When females become pregnant, they will create a den
for themselves and they will stay there to give birth and will be there without
food between 4-8 months, (Atkinson and Ramsay 1995) so it is very important
that the females are able to get enough energy throughout the rest of the year.
The weight of the female will greatly affect the litter size, mass of the young
and the young’s survival (Derocher and Stirling 1996) as well as the female
herself. Maternal food stress can cause an affect on the milk that is produced
which could greatly affect the cubs (Derocher et al 1993), whereas the adult
polar bears are able to survive better and it is only when there are really
severe conditions they will get affected as they are able to survive long
periods without any food (Atkinson and Ramsay 1995). With the ice break ups
occurring, this is causing a decrease in litter size when the females are
becoming pregnant which can cause a decrease within the population size (Lewis,
et al 2011). With all these changes causing a strain on reproduction within the
polar bears and a decrease in food availability, it could cause a decrease in
population growth rates or population decline (Thiemann et al. 2014). The polar
bears which are situated within the Western Hudson Bay show declines in
survival, body condition, population abundance and reproductive success and
this is predicted to be happening due to the increased rate of food stress
within the species due to the prolonged fasting periods (Regehr et al. 2007).
At the Western
Hudson Bay in Canada, the ice will melt completely every year which means that
the polar bears are actually forced to live on the sea shore for several
months, and with the ice breaking up earlier it can cause all the problems such
as struggling to survive (Regehr et al. 2007, Caswell et al. 2010) and with the
polar bears having limited food and then coming to live on the shore, they may
be deficient in energy (Gormezano and Rockwell. 2009). Due to coming to the
shore and having poor body condition, this can get worse due to having to fast whilst
being there and then the reproduction and survival of young, subadult and older
polar bears reduces (Gough et al. 2008). Although, some polar bears will take a
great advantage of the different marine mammals which are situated at the sea
shore and any carcasses on the shore such as bowhead whales (Bentzen et al.2006).
Polar bears seem to have a preference in where they
are situated, such as the polar bears in southern Beaufort Sea prefer to be situated
on sea ice covered shallow waters of the continental shelf (Durner 2009) where
the biological productivity (Wang et al. 2005) and where the seal populations
are high (Calvert et al. 1982). Seals are mainly hunted
within the high central and Eastern Arctic and along the south-eastern Baffin
Island, meaning that around the Western arctic they weren’t significantly
hunted (Smith 1980). This could indicate that a good place for the polar bears
to find a high food source is within the Western Arctic areas as they will
thrive there more than the other places due to them not getting hunted in that
area. Smith (1980) also states that the polar bears will hunt the seal pups
rather than the adults, this suggests that the pups will be an easier food
source to obtain than the adult seals.
Many of these papers have focused on the female adults
and how global warming will affect them and how it will affect them growing
their offspring and the amount of offspring they will produce with these harsh
conditions. Although these are all very important issues to be looked at, there
isn’t information about how the offspring will cope after being weaned from the
mother and the struggles they will go through on their own and learning how to
hunt ect. The papers also don’t really focus on the male polar bears, it states
the problems overall for all of the polar bears but doesn’t go into a deeper
insight like there has been within the female polar bears. There also hasn’t
been research into how finding a mate could now also be a challenge as with the
ice melting it will be more difficult to travel around and search for a mate
and without the support of the ice, these animals may struggle to also
reproduce. Most of the papers also seemed to base their research at the Western
Hudson Bay, this would indicate that they were studying the same group of bears
which wouldn’t give much of a variety within the data. There was also a difference
within the group sizes that were looked at, some of the papers didn’t study as many
polar bears as the others which could affect the results that were obtained,
one of the papers looked at about 161 individuals and getting samples from them
(Derocher et al 1993), whereas another paper looked at the whole population
within the western coast of Hudson Bay (Regehr et al. 2007).
More research needs to be taking place looking at the
affects of global warming on the cubs and how it affects them growing up. It
would be interesting if there was an insight in the affects of the young
learning different skills such as the parents teaching the offspring how to
hunt, swim, find appropriate land for them to live and hunt on. There should
also be more research on how the males are affected within their daily lives
and tasks they have to carry out such as mating and finding a mate, providing
shelter and food for the offspring and the female polar bear. In order to
broaden the research, other locations could be looked at rather than just
Western Hudson Bay, being able to study different groups of polar bears and see
if they are being affected in the same way. Some of the researchers could also
look at a bigger variety of polar bears, so they are able to get more data and
see other ways that the polar bears are being affected and whether there are
some struggles that are affecting the species more than other things. For example, the struggle for food could be
more common than the offspring not being healthy.
Looking at this data, polar bears are extremely dependant
on the sea ice but scientists seem to have found a link between the
productivity of the polar bear population and then the sea-ice change (Peacock
et al. 2011). This would suggest that the polar bears themselves are not
helping themselves when it comes to the ice being melted. Due to what the other
papers have stated, just a few years down the line there will be an even bigger
decrease in the population of polar bears as they are struggling due to the
reduction in ice. Global warming is having a big impact on the daily life of
polar bears and is making it very difficult for them to be able to survive.
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