Predator Management 2004 Update
Posted on 11/23/2004
BISMARCK, N.D.—Delta Waterfowl's predator management program shifted into high gear in 2004 with a record number of sites and continued excellent nest success.
This spring Delta had eight 36-square-mile predator blocks covering 184,320 acres scattered across the Prairie Pothole Region (PPR) of North Dakota. Each site had a professional trapper who removed nest predators like raccoons and skunks during the breeding season.
Five of the eight sites were monitored for nest success and two of those were paired with untrapped (control) sites which contained similar habitat and densities of breeding ducks.
The Cando site in the drift prairie of northeastern North Dakota reported a remarkable 86 percent nest success, the highest in the 10 years Delta has conducted large-scale trapping. Overall the trapped blocks averaged 57 percent nest success.
Scientists say ducks must achieve 15 to 20 percent nest success in order to maintain the existing population, but scientific research showed that across much of the PPR, nest success had slipped below that level by 1990. Nest-raiding and hen-eating predators are known to be the major reason that nest success had slipped below maintenance levels. All the monitored sites were well above the break-even level.
The Minnewauken site reported 62 percent nest success, Pleasant Lake was 53 percent, Walsh had 43 percent and Harlow 42 percent.
"Ducks that don't get out of the egg don't migrate," says Delta President Rob Olson, "and once again our predator work dramatically increased nest success. We're proving that predator management works, and that it works on a large scale."
The control blocks also achieved high nest success, one coming in at 37 percent and the other at 27 percent. Says Biologist Joel Brice, who heads up the predator management program, "The US Fish and Wildlife Service helps us pick the areas for our predator management work. Those areas typically comprise 20 to 40 percent grass nesting cover. Modeling work by the Service suggests we should see nest success in the 15 to 20-percent break-even level on those sites.
"Because nest success varies over space and time, it doesn't surprise us when we get a control site that achieves high nest success. We're always pleased when we see high nest success on the untrapped sites. After all, high nest success is what it takes to produce ducks."
For more information, contact Rob Olson or John Devney at 1-888-987-3695