Predator Control Remains Controversial, Despite Successes

by Doug Smith Minneapolis Star-Tribune
Published June 22, 2003

CANDO, N.D. -- The fox den was vacant, and its former occupant likely wasn't returning.

The evidence: Three duck nests filled with eggs were safely hidden in the lush knee-high green grass within 20 yards of the den. The mallard, bluebill and gadwall hens warming those eggs flushed when human visitors approached, but would return.

"If it was an active fox den, these eggs wouldn't be here now," said Rob Olson of Delta Waterfowl.

It was no accident that the den was vacant.

The area is part of a 36-square mile tract of prime waterfowl habitat where predators -- primarily skunks and racoons but also foxes -- are being trapped each spring during the waterfowl nesting season in an attempt to boost duck production.

It is one of eight such areas totaling 288 square miles -- more than 184,000 acres -- in North Dakota. It's an ambitious and somewhat controversial undertaking -- one that could have ramifications for waterfowl management elsewhere.

But those involved -- Delta Waterfowl researchers and U.S. Fish and Wildlife Service officials -- say predator control is working. Nest success -- defined as at least one egg hatching in a duck nest -- is far greater here than in nearby control areas with similar habitat but no predator trapping.

"We're easily doubling nest success on average, and more than tripling it in some cases," said Roger Hollevoet, U.S. Fish and Wildlife Service district director in the Devils Lake area, where trapping is occurring on six 36-square-mile areas.

Wildlife officials say ducks need a 15 to 20 percent nest success to maintain the duck population. Nest success typically varies depending on habitat, weather and predators. But average nest success in the prairie pothole country has declined over the years, and an increase in predators could be one reason for that.

At the area with the vacant fox den being trapped near Cando, N.D., called the Nikolaisen area, nest success was 66 percent in 2000, compared to a 16.5 percent in a nearby control area. In 2001, it was 73 percent at the trapped area and 27 percent in the control area. Last year, nest success was 42 percent in the trapped area and 20 percent in the control area.

"We know that trapping generally gives us about 2 1/2 times the nesting success," said Olson, Delta Waterfowl's vice president of operations. Six years of predator management studies by Delta has shown an average 43 percent nest success. Control sites have averaged 14 percent nest success.

"I'm sold on it," said Hollevoet.

But both Olson and Hollevoet are quick to point out that predator control isn't a panacea. Habitat remains the key for waterfowl production and should remain the focus of hunters, conservation groups and government agencies, they say. For ducks, that means water and grasslands, and lots of both.

"I look at predator control as just one management tool," Hollevoet said earlier this month as he drove past potholes brimming with ducks and surrounded by fields of grass.

But it's a management tool that deserves consideration, both say.

Trapping controversy
Delta Waterfowl, a 35,000-member conservation group based in North Dakota and Manitoba, has been at the forefront of promoting trapping as a waterfowl management tool. But the issue has been controversial. Ducks Unlimited, the 700,000-member conservation group headquartered in Tennessee, has discouraged predation management.

The concern, in a nutshell, is that money spent on predator management is money that won't be spent securing or improving waterfowl habitat. Wildlife managers and conservationists are divided on the issue.

The spending of dollars in North Dakota has raised eyebrows of opponents. Arkansas and Louisiana have contributed state duck stamp dollars to predator control in North Dakota. (Many of the ducks produced in North Dakota end up in those two states.) Arkansas contributes $50,000 yearly and Louisiana is contributing $100,000 annually for the next five years, Olson said.

Trapping at the Nikolaisen site is being paid for by Arkansas duck stamp dollars.

A statement issued in March by the Mississippi Flyway Council, an organization of waterfowl biologists and administrators representing 14 states (including Minnesota) and three Canadian provinces, criticized predator control.

"The council does not support the practice of predator removal as a viable management practice to improve waterfowl recruitment over the long-term or over large geographic areas," the statement said.

Money spent for predator control competes with habitat acquisition, management and enhancement, the paper declared. Also, "sustaining high nest success means annually removing animals, with all the attendant costs and potential controversy," the statement said.

The council also said there are ethical concerns about trapping animals in the spring when their pelts are worthless. Others have said that the issue could be ripe for anti-trapping and anti-hunting groups, and that society simply may not accept large-scale predator control.

Ducks Unlimited has offered similar arguments. "For a variety of science-based reasons, DU's leaders have determined that providing habitat is the best long-term measure to increase nesting success and to bolster populations of ducks and other wildlife well into the future," the group said in a position statement.

Trapping costs
Delta Waterfowl's Olson dismisses those arguments, and said the Mississippi Flyway Council's paper was "the most unscientific and biased assessment" of a wildlife management practice that he has ever seen. "It's political," he said.

"Predator management is another waterfowl management tool, like hen houses, wood duck boxes, island habitat and predator exclusion fences," he said. "Why did they only deal with predator management?"

Yes, predator control involves regular costs, but so does habitat management, Olson said.

Hollevoet and Olson said it costs about $25,000 to trap predators from one of the 36-square-mile (23,000-acre) zones, including $20,000 for a trapper. That amounts to a little more than $1 per acre. Trapping is done only from March 1 to July 1, while ducks are nesting.

"It's one of the cheapest management actions we do," Hollevoet said. "I can't even spray for weeds at $1 an acre."

Still, he acknowledges that it's impractical to trap predators in the entire prairie pothole region of North Dakota. Instead, he is targeting some of the highest duck production areas, trying to get the most bang for the buck.

"It's a valuable management tool," he said. "Is it a tool we use instead of habitat development? No, it's not. We need habitat. But there's only so much habitat you're going to get into public ownership or programs."

Hollevoet said he works closely with both Ducks Unlimited and Delta Waterfowl, and doesn't get involved in the politics over predator management.

"As a wildlife manager, I need all the tools available to be successful," he said.

He has no doubt that the predator control in North Dakota is resulting in more ducks flying south. Critics say that despite the nest success numbers, no one really knows how many ducklings are surviving to join the fall flight.

"That's true," said Delta's Olson. "And we want to do research to look at that. But no one also knows how the money we spend on habitat or on nesting structures affects the fall flight either."

While Delta has chapters in Minnesota, the organization isn't involved in any predator management in the state and very little has been done. And the Minnesota Department of Natural Resources is lukewarm, at best, to the idea.

"Our primary approach to this issue will be to continue to focus on landscape level habitat improvement," Tim Bremicker, DNR wildlife division director, wrote last year in a letter explaining the DNR's predator control position.

"The DNR isn't opposed to predator management," said Jeff Lawrence, DNR waterfowl specialist. "We haven't undertaken it, and I would say we don't intend to, either. But we may reconsider it down the road."

Predators still thrive
One thing appears certain: despite the trapping efforts in North Dakota, predators are not being wiped out in the trapped areas. In fact, their numbers are holding steady.

At the Nikolaisen site, trappers killed 298 animals in 1999, 289 in 2000, 447 in 2001, 378 in 2002 and 268 by June 15 this year. The vast majority are skunks and racoons.

"It tells me we're having no impact to the predator population," Hollevoet said. "We're not getting them all. It's physically impossible. We're just trying to create a balance during the nesting season. We're still losing nests to predators."

Both Olson and Hollevoet say the current predator population is a product of the major land-use changes that have occurred since settlement.

"We used to have a much larger predator base here, prairie grizzly bear and wolves," Hollevoet said. "We had an ecosystem that created its own balance. Now we have a landscape that looks nothing like it did in pre-settlement times. We've changed the predator base to these small, efficient predators that are constantly seeking ground nesting birds."

Controlling some of those small predators makes sense from a biodiversity standpoint, Olson said. He said Delta wants to study the impact of the predator trapping on other wildlife. For example, the number of shorebirds in the trapped areas seem to have increased.

"Predator management is not the savior for waterfowl," Delta says in a report. "It is simply another effective arrow in the quiver of waterfowl managers."

Copyright 2003 Star Tribune. Republished here with the permission of the Star Tribune. No further republication or redistribution is permitted without the express approval of the Star Tribune.