SREL Reprint #0287




An Evaluation of the Octagon Census Method for Estimating Small Mammal Populations

J. B. Gentry, Michael H. Smith and John G. Chelton



The aim of this study was to evaluate the results obtained from the octagon census method.  Trapping was conducted on the census lines for 28 days.  On day 28 a 540 m assessment line was laid out across the octagon for the purpose of determining the width of the area sampled by the octagon census lines.  Traps on assessment lines were set for 4 days.  Octagons were set up in four different areas of the mesic-hardwood forest and first trapped during the summer and then retrapped during the winter.  Theoretically, captures along the assessment lines should show a decline as the census line is approached.  This was not the case; more animals were capture at assessment line stations near the census lines than at those assessment line stations farther away.  The sudden appearance of animals in an area supposedly voided of inhabitants is difficult to explain.  However, because of this phenomenon, the octagon census method failed in its objective of giving density estimates.


SREL Reprint #0287

Gentry, J.B., M.H. Smith, and J.G. Chelton. 1971. An evaluation of the octagon census method for estimating small mammal populations. Acta Theriologica 16:149-159.

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