Abstract:
Although it is well known that humans are strong modifiers of their
environment, there is a need for greater understanding of human-wildlife interactions,
both historically as well as currently. Historical journals can help shed light on early
human-wildlife interactions, and the Lewis & Clark journals contain some of the
earliest and detailed written descriptions of a large part of the United States before
Euro-American settlement. I used the journal entries to assess the influence of humans
on wildlife distribution and abundance. Areas with denser human population, the
Columbia Basin and the Pacific Coast, had lower species diversity and abundance of
large mammals. The opposite was observed on the Plains. Overhunting before Euro-
American contact accentuated by the introduction of the horse may have been major
contributors responsible for the historic absence of some species that are present in the
archaeological record. The information gained from the Lewis & Clark journals shows
the considerable human influence on wildlife under relatively low human population
densities. This has major implications for conservation biology and ecological
restoration, since human influence is often underestimated when considering the pre-settlement
condition.
Species ranges are dynamic and change greatly over time. In order to identify
large-scale patterns in range contractions and/or expansions, I compared historic and
current geographical ranges of 43 North American carnivores and ungulates. Seventeen
of the species had undergone range contractions over >20% of their historic range. In
areas of higher human influence, species were more likely to contract and less likely to
persist. Species richness declined considerably since historic times, and the temperate
grasslands and temperate broadleaf/mixed forest biomes lost the highest average
number of species, while the boreal forest and tundra showed fewer numbers of species
lost. The study of species range changes contributed new quantitative information about
human influences on range contractions in North America. The results can be used to
improve our knowledge of historical reference conditions, for the creation of wildlife
reserves, and for wildlife re-introductions.
