The Affects on "Denning" of the Grizzly Bears

 "Denning" or going into hibernation time has been shifting in time of occurrence.  Biological events such as the reproduction, flowering, etc could be affected by timing in their events due to the climatic changes happening.  This can cause an asynchrony in the timing of many things such as migration, change in mating times, and much more [13, 14].  In the case of Grizzly Bears, Denning is affected and has the potential to grow earlier in the season, where bears exit hibernation. In the occurrence of exiting hibernation early, there is also the chance of other primary producers and other food sources have been influenced differently than one another [4].

Grizzly Bear  During Hibernation [16]

In the IPCC Summary 2007, they go over the different causes of an increase in global warming, the main reason being an increase in greenhouse gases.  In a study where they went out to explain how these changes in greenhouse gases are causing a change in precipitation rate and evaporation rates which further influence primary producers due to water stress [10].  The study goes on to explain one of two possible outcomes due to the increase in CO2, it could increase plant production due to this direct increase, or decrease due to the increase of constraints put upon these producers. 

The potential trophic level asynchrony is a definite possibility in the case of Grizzly Bears and their sources of nutrients [14].  This could result in an earlier occurrence in hibernation ending, where the bears come out and begin to feed on the many types of food.  Models showing how reproductive output is highly influenced by both the bear population and the Whitebark Pine, a vegetational primary food source of the Grizzly Bears that is one of the main parts of their diet.  The possibility of this primary food source and the grizzly bears hibernation changing, there could be a large impact on the reproductive rate of the population in Greater Yellowstone [10].  By the year 2050, the peak runoff for Greater Yellowstone's rivers occurring 10-20 days earlier than before, showing there is more than just vegetation being influenced.  In order to explain how this runoff would be directly affected due to these climatic changes, the previous trend of increased temperature and the potential 3.5 degrees warming in the area would increase the time of melting in the spring and result in this 10-20 day change [2].  This goes to show how little it takes to cause a fairly significant change.  This website also states that the Whitebark Pine I have previously mentioned has had about 85% of its population die off.