Experts study wildlife control

The Associated Press

SIOUX FALLS, S.D. -- A study in northeast South Dakota will examine the value of predator control as a way to put more ducks and pheasants into the wild each summer.

With limited grassland and the prospect of fewer Conservation Reserve Program acres, it's important to get the maximum nesting success out of available habitat, say those involved.

Delta Waterfowl; the state Department of Game, Fish & Parks; the U.S. Fish and Wildlife Service, and South Dakota State University are part of a two-year, $200,000 study on removing predators that destroy nests.

Four tracts of land in Roberts, Clark and Codington counties are being used. Each is about 36 square miles in size, or roughly 23,000 acres.

Trappers will remove predators -- mostly skunks and raccoons -- in two of the blocks of land from mid-March to mid-July, when the nesting season ends. No predator control will be done on the other two blocks.

Duck and pheasant nests are found, marked and checked frequently to see if there's a successful hatch or if a predator has found the nest and destroyed it.

Participants hope to draw some conclusions when comparing the hatch rate in the trapped tracts to the rate in the two parcels without predator control.

"The populations of those two predators are probably the highest ever recorded in history," said Chuck Dieter, a professor and wildlife biologist at South Dakota State University who's overseeing the collection of information on nesting success.

"In areas with only 20 to 40 percent grassland, they have a lot less area to hunt to find the nest."

Delta Waterfowl has been doing similar predator control in North Dakota and Canada where it's seen a doubling of nesting success for ducks, said Joel Brice, manager of Conservation Programs at Delta's Bismarck, N.D., office.

"This would be another tool in waterfowl management -- not a silver bullet or a cure-all -- but in a lot of areas the water management community has invested a large amount of money and in some of these areas, there isn't enough habitat to spread out the predators and spread out the ducks, so nesting rates can be quite low," Brice said.

Delta is paying the costs for the two trappers.

A key element to the study was finding study areas that have similar amounts of grassland -- 20 to 40 percent -- and a similar density of ducks, said Spencer Vaa, a waterfowl biologist for the GF&P in Brookings.

The target was to find 800 duck nests and 400 pheasant nests on the four plots. Instead, they're working this season with about 900 duck nests and 200 pheasant nests, Vaa said.

"Pheasants are harder to find," he said. "It doesn't mean there are less pheasants, but when you flush a pheasant that doesn't mean the nest is right there. They run off first."

A similar study was done in South Dakota 30 to 40 years ago, but this is the first of its kind in the state involving such a large area, said Dieter.

"I think it's coming at a very good time because if we lose a lot of CRP -- which may happen -- it's really important to maximize the production of ducks and pheasants in the grasslands that are left," he said.

On large game production areas, the cost of predator trapping during the nesting season might be a cost-effective management tool, Vaa said.

"Everything costs money to do on a wildlife area -- if you burn it with a prescribed fire or planting cover or spraying weeds. Maybe if you just add a little more money by taking predators out it might double the nesting success."

Good habitat is key, Dieter said.

"If you have wide areas of good grass habitat it's harder for predators to find the nest, their search time is longer," he said.

"If it's smaller areas, a few predators can do a lot of damage. Waterfowl like to nest on islands, and if you have an island with one or two raccoons on it, they can basically ruin every nest on the island."