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.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

The Use of Portable Thermal Imaging for Estimating Deer Population Density in Forest Habitats

R. M. A. Gill, M. L. Thomas and D. Stocker
Journal of Applied Ecology
Vol. 34, No. 5 (Oct., 1997), pp. 1273-1286
DOI: 10.2307/2405237
Stable URL: http://www.jstor.org/stable/2405237
Page Count: 14
  • Read Online (Free)
  • Download ($18.00)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
The Use of Portable Thermal Imaging for Estimating Deer Population Density in Forest Habitats
Preview not available

Abstract

1. The reliability of deer population management could be improved with good density estimates, but current methods are either labour-intensive or suffer from uncertainties regarding accuracy. 2. Visibility varies substantially in forests depending on stand type, age and understorey vegetation. In such conditions distance sampling would be an efficient estimation method, but observer disturbance often results in bias when the method is applied to deer. 3. The performance of thermal imaging for estimating deer density by distance sampling was assessed in seven forest deer populations. Thermal imaging equipment can detect the long-wave energy radiated by natural objects, clearly revealing warmbodied animals even if partly obscured by vegetation. 4. Many more deer were detected at night using a thermal imager than along the same transect routes in daytime. Detection distances were correlated with visibility but were substantially longer than the average distances at which most animals were disturbed. Most deer were detected without causing prior disturbance. 5. Densities were estimated with a coefficient of variation ranging from 10-2-28.4%. Precision depended on sampling effort and sample sizes obtained. 6. A Monte Carlo simulation revealed a quadratic relationship between accuracy and visibility, with accuracy increasing with average visibility and a tendency for deer to select more open habitats within a forest. Under conditions that are likely to be typical of temperate forests (< 40% thicket and neutral selection, or < 70% thicket if thicket is avoided), accuracy was generally good and changed relatively little in relation to visibility and habitat selection. 7. Likely sources of bias as well as alternatives to thermal imaging are discussed. It is concluded that the method would be suitable for estimating ungulate densities in forests with an adequate network of tracks.

Page Thumbnails

  • Thumbnail: Page 
1273
    1273
  • Thumbnail: Page 
1274
    1274
  • Thumbnail: Page 
1275
    1275
  • Thumbnail: Page 
1276
    1276
  • Thumbnail: Page 
1277
    1277
  • Thumbnail: Page 
1278
    1278
  • Thumbnail: Page 
1279
    1279
  • Thumbnail: Page 
[1280]
    [1280]
  • Thumbnail: Page 
1281
    1281
  • Thumbnail: Page 
1282
    1282
  • Thumbnail: Page 
1283
    1283
  • Thumbnail: Page 
1284
    1284
  • Thumbnail: Page 
1285
    1285
  • Thumbnail: Page 
1286
    1286