. Distribution of mammals in Colorado. Mammals. 184 MONOGRAPH MUSEUM OF NATURAL HISTORY NO. 3 factors on suitability of sites for beavers. Where basic site qualities are suitable, beav- ers have a far-reaching effect on the environ- ment, influencing the water-table and runoff, plant succession, and pedogenesis (see Neff, 1957). The beaver is abundant in some parts of Colorado today, but in the late Nineteenth Century, populations were reduced by over- exploitation to dangerously low levels. From 1900 to 1955 only "nuisance beaver" were trapped. During that period, numbers in- crease
. Distribution of mammals in Colorado. Mammals. 184 MONOGRAPH MUSEUM OF NATURAL HISTORY NO. 3 factors on suitability of sites for beavers. Where basic site qualities are suitable, beav- ers have a far-reaching effect on the environ- ment, influencing the water-table and runoff, plant succession, and pedogenesis (see Neff, 1957). The beaver is abundant in some parts of Colorado today, but in the late Nineteenth Century, populations were reduced by over- exploitation to dangerously low levels. From 1900 to 1955 only "nuisance beaver" were trapped. During that period, numbers in- creased on public lands to the point that habitats were degraded. The over-population in certain areas was reduced by epizootic tularemia in 1957-1958, but since 1960, popu- lations have increased steadily. In the 12 trapping seasons between 1958 and 1969, annual harvest has increased from about 5700 to slightly over 10,000 animals. In 1957-1958, per cent of the harvest was by state trappers, whereas in 1969, they took only per cent of the harvest. As populations have increased, the numbers of animals trapped by landowners have increased tremendously (623 in 1958, 6705 in 1969, high of 7373 in 1964). There has been a concomitant de- crease in numbers of transplants by state of- ficials (655 in 1961, 129 in 1969—unpublished data from Division of Game, Fish and Parks). The program of management of beaver in Colorado has shown excellent results and is based on thorough research. Some important reports resulting from such studies include Yeager and Hill (1954), Retzer et al. (1956), Yeager and Rutherford (1957), and Ruther- ford (1964). Yeager and Hay (1955) com- piled an extensive bibliography on ecology and management of beaver. The natural history of Coloradan beaver has been the subject of considerable popular and semitechnical literature. The most im- portant of the early workers was Enos A. Mills, pioneer naturalist of the Longs Peak region. Observations on the so-called
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Keywords: ., bookcentury1900, bookcollectionbiodiversity, booksubjectmammals
