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Title:Federal Aid Project No. W-49-R(25) Study I: Population Trends and Characteristics Job No.8: Beaver investigations
Author(s):Hubert, George F., Jr.; Klinedinst, D.B.
Castor canadensis
Jo Daviess county
population trends
mandibular teeth
Abstract:A partial census of the beaver (Castor canadensis) inhabiting the inland streams of Jo Daviess County, Illinois, was conducted during the fall of 1977. A search of 115.7 km (44.1 percent) of the streams present yielded a county-wide population estimate of 184 to 219 animals. This estimate was 25 percent lower than the one based on a similar census conducted in 1950. Beaver sign observations were also recorded for 463 km of stream sampled as a part of the 1977 statewide wood duck (Aix sponsa) census. Individual colonies could not be delineated from the spring observations. A sample of 20 unskinned beavers was examined at a fur house in DeKalb County, Illinois, between 15 November 1977 and 13 January 1978. The sex ratio of these animals was 1:1. Body weights ranged from 5.6 to 29.0 kg. Age composition of the sample was 11 kits (55 percent), 5 yearlings (25 percent), 2 two-year olds (10 percent), and 2 adults (10 percent). Aging techniques based on body weight, tail dimensions, zygomatic breadth, and saggital crest development appeared to overage 29 to 50 percent of the specimens and have little applicability for winter-trapped beaver taken in Illinois. The development of mandibular teeth seemed to be the most reliable and consistent of all age criteria employed.
Issue Date:1978-05-22
Publisher:Illinois Natural History Survey
Genre:Technical Report
Publication Status:unpublished
Peer Reviewed:not peer reviewed
Rights Information:This document is a product of the Illinois Natural History Survey, and has been selected and made available by the Illinois Natural History Survey and the University Library, University of Illinois at Urbana-Champaign. It is intended solely for noncommercial research and educational use, and proper attribution is requested.
Date Available in IDEALS:2015-05-20

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