Improving Prairie Pond Counts with Aerial Video
and Global Positioning Systems
Management Implications
The aerial video system we describe required a separate flight to acquire video imagery because the aircraft altitude required to identify ducks does not permit videography of the entire transect width and thus requires additional expenditure of resources. However, this system offers several enhancements to aerial BGS methodology. Estimates of omission and commission errors can be calculated comparing ponds from video interpretation with ponds from ground survey. The video system provides an image of the spatial location of ponds. The location of ponds identified as commission errors from the comparison of the video interpretation with the ground survey could be inspected in the field to verify that these are indeed errors in video interpretation rather than errors in ground survey. If ponds are present at these locations the list of ponds for the ground survey could be updated.
There is also a need to incorporate geographic information systems technology in production of maps for ground BGS and in data analysis. The video system enables estimation of all ponds, thus avoiding subjectivity of excluding Type I ponds from aerial BGS. Consistent application of sampling criteria for ponds by video interpreters and ground crews is critical to obtaining unbiased estimates. The definitions of wetlands and water levels used in BGS need to be revised and made more precise. Although not tested, video images can be used to obtain additional habitat information, such as pond area, land cover and use of upland habitats, and the spatial relationships of ponds and uplands useful to waterfowl management. This habitat information could be used to improve estimates of duck population parameters as well as trends in habitat status. A video survey of ponds should consider alternative sample designs, including shape and size of sample units, as high sampling variability of ponds among transect segments of the BGS often makes detecting annual changes in pond numbers on a regional basis difficult.
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