An ecological study of the Columbian black-tailed deer in a logged environment

A study of the effects of old-growth Douglas-fir logging upon the Columbian black-tailed deer Cdocoileus hemionus colunibianus (Richardson) was conducted from January 8 to December 30, 195d in the H. J. Andrews Experimental Forest near Blue River, Oregon. Objectives of the study were to obtain information about the activities, behavior, movements, migrations, and general ecology of the black-tailed deer in a logged environment.
The night spotlight sampling method was used to study the deer while they occupied the summer range (the Andrews Forest) from April through September. The entire road system of the area was sampled twice weekly, and deer present were sighted by eye reflection of the spot-light beam. With the aid of binoculars, an attempt was made to classify deer sighted according to age, sex, activity and location. Sampling was begun one to two hours after darkness, and the sample was usually completed in three to four hours. Using procedures similar to the spotlight method, daylight samples were taken during June and July on the some dates as the spotlight samples. Daylight sampling was begun shortly after daylight and required three to four hours to complete. In the wintering grounds at lower elevations to which the deer migrate in September these sampling methods proved unsuccessful. Therefore, a foot travel method was employed for this segment of the study, and much greater emphasis was placed upon the interpretation of sign.
Pre-logging records indicated that few deer used the area prior to initial logging in 1950. Deer numbersincreased, however, in the excellent browse conditions of brushy successional stages of vegetation following the removal of the virgin timber. The creation of edge habitat by the steggerod-setting, clear-cut unit method of logging further benefited the deer population.
A sex ratio of 1 buck per 3.24 does and an age ratio of 4.19 adults per yearling were derived from the spotlight data. Fawning occurred mainly during June,and a ratio of 1.4 to 1.5 fawns per doe was approximated from the spotlight and daylight samples. Single deer or groups of two were encountered most frequently during the summer months, while groups numbering three or more predominated during periods of migration and during the winter months. The overall effect of predators on the herd appeared to be relatively unimportant.
Weather conditions, especially temperature, appeared to affect the daily activities of deer. Night spotlight samples taken following days of high temperature averaged higher in deer sightings than samples following days of low temperature. This was the result of more deer being active ( as opposed to bedded ) on nights following days of high temperature. wide variations in day to day resulted in similarly wide variations in the number of deer sighted by the spotlight sampling method. Deer were distributed nearly evenly between north and south slopes until June when a movement to the north slope occurred. This aspect was slightly favored by deer through the remainder of the summer. On the north slope, units below 2,500 feet in elevation were preferred, although deer showed a tendency to move upward during mid-summer. In August this trend was reversed when a sharp downward movement occurred. On the south slope, elevational preference was evident only during August, when 83 percent of the deer were sighted above 2,250 feet.
The spring migration into the Andrews Forest occurred as a gradual upward drift in Narch, and by early May most of the population had arrived. Many deer were found to return to their home ranges of the previous summer. The downward fall migration followed two main routes, and was unusual in that it occurred during September, long before the advent of inclement weather. Both migrations were correlated with temperature changes. Bottom lands and sites of old logging operations or burns on exposed south slopes were utilized by deer as wintering grounds.