Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

The Pellet-Group Count Technique for Big Game Trend, Census, and Distribution: A Review

Don J. Neff
The Journal of Wildlife Management
Vol. 32, No. 3 (Jul., 1968), pp. 597-614
Published by: Wiley on behalf of the Wildlife Society
DOI: 10.2307/3798941
Stable URL: http://www.jstor.org/stable/3798941
Page Count: 18
  • Download ($42.00)
  • Subscribe ($19.50)
  • Cite this Item
The Pellet-Group Count Technique for Big Game Trend, Census, and Distribution: A Review
Preview not available

Abstract

Systematic pellet-group counts for big game trend, census, and distribution originated in the late 1930's and have since been used for a variety of research and management objectives. Their chief advantage is that pellet groups can be sampled by standard field plot techniques. Most pellet-group plots have been circles or long narrow rectangles, usually distributed in some form of stratified-random design. Sample plot layout can often be planned to minimize variance between plots or groups of plots. Sampling technique will depend upon local objectives, but some guidelines have been recognized. Sampling is generally more efficient in areas of higher pellet-group density. If pellet groups are distributed uniformly, a large area may require no more plots for adequate sampling than a small area. Pellet groups generally are deposited in a clumped pattern. Sampling intensity estimates can be made on the basis of the mean and variance derived from preliminary sample counts. Daily defecation rate is needed for computing deer-days use or total numbers of deer. Available data on defecation rate for wild native North American ruminants is tabulated, with some information on livestock and one exotic, the Barbary sheep. High defecation rate in deer has been observed to accompany high feed intake, high forage moisture content, high percentage of young in the herd, change in diet from roughage to concentrates, and the psychological impact of captivity. Observer bias arises mainly from differences in interpretation and from missed groups. Because of missed groups most counts will underestimate actual pellet-group density. Missed groups error is influenced by plot size and shape, type and density of understory vegetation, and observer fatigue and inherent visual acuity. Sources of interpretational differences include decisions concerning peripheral groups, scattered groups, and the minimum number of pellets to be counted as a group. Common practice requires use of permanently marked plots which are periodically cleared. Temporary plots are sometimes used where the deposition period can be dated by reference to leaf-fall, by deformation of pellets due to emergence of succulent feed, or by estimation of the period of herd occupancy of seasonal range. Such dating schemes introduce an additional source of observer bias. Pellet group counts have been unworkable at times because of rapid loss of pellets by insect attack or heavy rains, because of difficulties in identifying pellets of different species, or because of extremely dense vegetation. In a few cases the pellet group count has been tested against known numbers of deer in fenced areas, or against other census techniques. Reasonable accuracy of estimate has been obtained in many cases.

Page Thumbnails

  • Thumbnail: Page 
597
    597
  • Thumbnail: Page 
598
    598
  • Thumbnail: Page 
599
    599
  • Thumbnail: Page 
600
    600
  • Thumbnail: Page 
601
    601
  • Thumbnail: Page 
602
    602
  • Thumbnail: Page 
603
    603
  • Thumbnail: Page 
604
    604
  • Thumbnail: Page 
605
    605
  • Thumbnail: Page 
606
    606
  • Thumbnail: Page 
607
    607
  • Thumbnail: Page 
608
    608
  • Thumbnail: Page 
609
    609
  • Thumbnail: Page 
610
    610
  • Thumbnail: Page 
611
    611
  • Thumbnail: Page 
612
    612
  • Thumbnail: Page 
613
    613
  • Thumbnail: Page 
614
    614