Barriers presented by towns and cities:
Using this Least Cost Path procedure is one technique for trying to estimate the relative connectivity of areas, routes, between protected areas. But there are some significant barriers already within this landscape. Towns and cities seem to be absolute barriers for travel of most large carnivores, and agricultural fields are almost impassable, particularly if there are ranches, houses, dogs, fences, and irate land owners with loaded weapons.
Major highways are also serious barriers. The more traffic a highway has, of course, the less likely it is that a bear could get across it successfully. This is an area of impact that's been looked at to some degree. In Florida, they've determined that traffic volumes of about 20,000 vehicles per day or more are virtually impassable to wildlife and will kill any animal that tries to get across. Up in Canada, the Trans-Canada Highway which goes right through the center of Banff National Park, has volumes that are just about that high.
Down in the Northern Rockies, we've got much lower traffic volumes. The major Interstates - I-90 comes right through here east to west and I-15 comes down through here north to south, - have fairly low volume now and they're not having too much of an impact on animals. But it's going to get worse.
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Narrative Index
BioForum Index
