Cookeville, Tennessee  38505

Introduction

•     Show differences in the accuracy of two population estimates.

•     Show how one estimate may require less work, but a better estimate is obtained using the lengthier method.

•     Literature cited

–    Research and Management Techniques for Wildlife and Habitats Edited by Theodore Bookhout, The Wildlife Society, Bethesda, MD  1996 (methods).

–    Forestry Suppliers Incorporated Catalog 52, 2001-2002, Jackson, MS (materials).

–    General Ecology Laboratory Exercises Edited by Daniel L. Combs and Frank J. Bulow, Tennessee Technological University, Cookeville, TN  1998 (methods).

Objective and Hypothesis

•    Objective

–   The objective of my project will be to compare the precision between the Schnabel and Lincoln-Peterson population estimation methods using a snail population on Blackburn Fork Creek.

•    Hypothesis

–   There will be no difference between the Lincoln-Peterson population estimate and the Schnabel estimate.

Materials and Methods

•    Materials

–   Insulated hip waders

–   Surber-type square foot invertebrate sampler

–   Collection tray

–   Marking paint (clear fingernail polish)

–   Ecological Methodology software

•    Methods

–     Randomly place the Surber sampler over an area of substrate with the net trailing downstream.

–     Substrate within the frame is disturbed, dislodging all gastropods which are swept into the net by the current.

–     Rocks and all other substrate material are then scrubbed thoroughly within the sampler to remove tightly adhering gastropods.

–     The snails will be placed in a collecting tray and marked with clear marking paint.  Results will be marked on the data sheets.

–     Animals will be randomly redistributed throughout the test area; then another sample will be taken.

–     This collection will be repeated once more (two recaptures) to satisfy the requirements for the Schnabel estimate (Bookhout 1996).

Results

•    The Peterson method gave an extremely low estimate for the number of snails in Blackburn Fork.

•    The Schnabel method gave a more realistic population estimate.

•    The accuracy of the estimate increased with the number of samples taken.

Conclusions

•    Although it takes more time to do numerous capture events, the estimate one receives is more accurate.

•    Biologists should use the Schnabel method over the Peterson method if at all possible.

•    Time should be the only constraint on the number of samples taken.

•    Accuracy is important making informed management decisions.

Acknowledgements

•   Dr. Cook

•   Dean Chauvin

•   Sharon Broyles

•   Momma