Detections of pronghorn from fixed-wing aerial surveys in Southeastern Wyoming using four angular bins defined by strut marks. Illustrates data where altitude above ground level (AGL) varies during the survey.
A data frame with 660 observations on the following 5 variables.
a numeric vector
a factor with levels N S
representing the survey direction
height above ground level
a factor with levels A B C
D which represent angular bands between breaks at
35.42,44.56,51.52,61.02,70.97 degrees. These angles were set based on
selected distance bins based on the target AGL.
number of pronghorn in the observed cluster
Each record is an observed cluster of pronghorn. The data provide the stratum for the observation, the direction of travel, the AGL at the time of the observation, the angular bin which contained the center of the pronghorn cluster(group), and the number of pronghorn in the group. The angular bins were defined by a combination of two window and five wing strut marks to define bin cutpoints for perpendicular ground distances of 0-65, 65-90, 90-115, 115-165 and 165-265 meters when the plane is 300' (91.4 meters) above ground level. The inner band is considered a blind region due to obstruction of view beneath the plane; thus th the line is offset 65 meters from underneath the plane.
Laake, J., R. J. Guenzel, J. L. Bengtson, P. Boveng, M. Cameron, and M. B. Hanson. 2008. Coping with variation in aerial survey protocol for line-transect sampling. Wildlife Research 35:289-298.