grouse
This is more complicated than one factor causing the decline in so many widely seperated areas. The natural world responds in varying ways to many causes at any one time. The tipping point can be brought about by a minor thing when the other factors are in place. In the north new factors have occurred in the last 2 decades, west nile virus and winter ticks are 2 of them, both added to habitat factors may be the tipping point maybe not. The result is not in doubt. Looking at what has happened to moose numbers across the southern range of their habitat is an example caused in part by the winter tick. We will probably never be able to lay blame on any one cause.
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