A Division of Wildlife-financed study of duck behavior along the South Platte River conducted by Josh Dooley, a graduate student at Colorado State University, used radio transmitters and banding to track the movements of mallards when exposed to various types of disturbance, including gunfire.
Among the findings:
• Ducks moved an average distance of 1.8 miles after disturbance.
• In only 16 of 276 instances of disturbance did ducks fly as far as 6 miles.
• No collared ducks vacated the study area completely.
• Ducks disturbed on off-river habitat rarely went to the river. Only 1 in 126 did so during early-season observations but were 24 times more likely to do so from December though February.
• As much as 75 percent of disturbed ducks returned to the original spot within five days.
• Overall waterfowl occupancy, ducks and geese, returned to normal within one day of disturbance.
• Eighty-nine percent of collared mallards and 86 percent of banded birds killed by hunters were taken in the study area.
Dooley concluded that subsequent management recommendations might consider shorter periods of closure and smaller buffer zones, rather than resting entire state wildlife areas. He also deemed partial-day closures of little benefit, while limiting nonwaterfowl activity when possible.
Dooley’s complete thesis, “Mallard response to experimental human disturbance and nonbreeding survival along the South Platte River in Colorado,” can be found online at http:www.colostate.edu/Dept/coop unit/thesis.html.
Charlie Meyers, The Denver Post
