Fall/Winter 2000

Current Research: Evaluating Camera Census Techniques on White-tailed Deer

Dr. Steve Demaris and Karen Brasher are conducting a research project titled "Infrared-triggered Cameras as a Survey Method for White-tailed deer in Mississippi". The highlights of their research are as follows:

Population size was estimated for enclosed deer populations in Mississippi during the fall and winter seasons of 1998 and 1999 using an infrared-triggered camera technique, a mark-recapture technique and a spotlight survey technique. Estimates generated from each technique were compared to a "best estimate" that was derived using recovery of tagged deer, picture information and supplemental video-taped observations.

Two different camera densities were used to estimate population size with the infrared-triggered camera technique: 1 camera per 100 acres and 1 camera per 200 acres. The researchers compared the population estimates derived with these camera densities to determine if a particular density captured a greater proportion of the population and to determine how many camera days were required for the proportion of the population filmed to stabilize. Additionally, they tested for sex-specific and season-specific differences with the above-mentioned techniques.

Using the camera technique with a camera density of 1 per 100 acres, estimates of population size ranged from 86-88% and 91-93% for bucks and does, respectively, of the population size. At a camera density of 1 per 200 acres, estimates of population size ranged from 57-73% and 51-58% for bucks and does.

Using a mark-recapture technique with females (utilizes photographs of tagged females as captures), estimates of population size ranged from 78-83% and 94-138% for bucks and does. With the spotlight survey technique, estimates of population size ranged from 47-57% and 63-68% for bucks and does.

Estimates generated with the camera technique at a density of 1 camera per 100 acres were generally closer to the "best estimate" for density, sex ratio and fawn crop with little seasonal variability. Whereas, with the camera technique at a density of 1 camera per 200 acres and with the mark-recapture technique, population estimates were more disparate from the best estimate and were seasonally variable. Their results indicate that the number of consecutive days required for a stable estimate of the male population (as compared to the "best estimate" of the male population) varies by season and camera density. With the 100-acre camera density, the population estimate of males stabilized after 6-8 days in the winter and 11-12 days in the fall. With the 200-acre camera density, the population estimate of males stabilized after 8-10 days for both fall and winter. Conversely, only 3-4 days are required for the sex ratio estimate to stabilize with the camera technique at the 100 or 200 acre camera density during fall and winter.

For more information on using the camera survey technique for deer, request the Research Highlight titled "Infrared-triggered Cameras as a Survey Method for White-tailed deer in Mississippi" from Karen Brasher, Forest and Wildlife Research Center, P.O. Box 9820, Mississippi State, MS 39762.