"For Hunters by Hunters"

The Need for Predator Control

By: Cliff Feldheim

Valley Waterfowl Biologist

There is no place on earth that has not in some way been altered by man, and North American duck habitats are no exception.  In the U.S. and Canada, prairies, were once largely treeless grassy areas that were ideal duck nesting habitats.  As the Prairies became farmed, tree rows and houses were built, and the once vast prairies were broken into much smaller sections.  Trees and man made structures have made the prairies habitable for animals that historically never lived there.  Raccoons, skunks, and red foxes existed in very limited numbers prior to European settlement.  However the eradication of wolves and coyotes, in combination with new denning sites, and ranching practices have allowed these predator populations to explode. 

The result for most species of ducks that nest in the prairies has been lower nest success.  Upland nesting ducks and dabbling ducks, do not adapt well to predators like the red fox that search grasslands looking for prey.  Female ducks, in large, try to hide in the grass to avoid predation, but become easy pickings for a red fox.  It’s generally accepted that nest success of 15-20% is necessary for a population to be stable (the number varies by species).  In the 1990’s, research suggested that nest success for upland nesting ducks was about 10% (well below the 15-20% mark).  In the last 20 years, numerous studies have documented that nest and hen predators are the primary cause of population decline and low production of ducks.

In 1994, Delta Waterfowl initiated a predator management program in the U.S. Prairies.  Professional trappers targeted red fox, raccoons, and skunks.  Since that time, study sites have ranged from 1 square mile (6,400 acres) to 36 square miles (92,160 acres).  Over the last 10 years, nest success on these managed sites has been consistently 200 to 300% higher than unmanaged sites.  In 2003, one 92,160 acre site had an 80% nest success. 

Despite Delta’s efforts to evaluate and restore a balance to the predator community on the Prairies, other conservation groups and many waterfowl biologists are adamantly opposed to predator management.  These conservation groups argue that we should be spending our limited money on restoration, conservation, and protection of habitat not predator management.  While this is good in theory, research suggests that given the current predator community in the Prairies, predator control is a much more viable option.

Many studies (both published and unpublished) from the Prairies have documented that relatively small tracts of land that are protected and conserved in the name of waterfowl actually end up having nest success consistently below the 15-20% mark.  While these projects may be good for conserving habitat and grassland wildlife, if they are paid for by duck hunting dollars they should produce ducks.  The Delta Waterfowl Report was quoted by saying, “But the issue on the table is ducks, and our best science tells us that habitat alone isn’t always enough to increase duck production rates. Dollars provided in good faith by duck hunters are a major source of funding for habitat projects, but in many cases hunters aren’t getting a fair return on their investment. Many of the elaborate and expensive habitat projects simply aren’t producing ducks. Many actually qualify as population sinks [habitat that attracts ducks but actually hurts the population because nest success rates are so low]” (Delta Waterfowl Report, Spring 2003). When push comes to shove, the only way we can preserve our tradition is by having ducks to shoot. In California we can learn from the example in the Prairies.  Compared to the Prairies, nest success in California has been studied relatively little.  The only published study, McLandress et al. 1996, examined nest success of mallards from 1985-1989 on Honey Lake, Ash Creek, Mendota, Gray Lodge, and Grizzly Island Wildlife Areas and at Sacramento, Delevan, and Colusa National Wildlife Refuges.  Nest success during this period was highly variable, averaging from 6 to 75%.

This study was conducted on habitats managed for wildlife; however, most of the waterfowl habitat is not managed for production.  Given this, and the fact that California’s landscape has been highly altered and fragmented, one can assume that nest success is lower than in most of the state.  Like the Prairies, California’s predator community has been significantly altered by human caused changes to the environment.  Similar to the Prairies, large mammalian predators are basically absent. Red foxes, skunk, and raccoon populations are artificially high due to native habitat destruction, lack of historic flooding, creation of suitable habitat, and agricultural production. 

In California, the question needs to be asked, how much habitat do we need to set aside and how should the habitat we have be managed to best produce ducks?  Most of our state and federal wildlife areas/refuges receive funding from duck hunting.  On some of these lands fields are set aside for nesting ducks, but on others they are only managed for wintering ducks (similar to most duck clubs).  We have the potential to raise a lot of ducks in this state and not just mallards. Cinnamon teal, gadwall, and wood ducks would greatly benefit if managed properly.  We have to wonder if small patches of nesting habitat are hurting not helping our local duck populations (with nest success below 15-20%).  Although predator management is politically unpalatable, it’s an insult to duck hunters that red foxes can be trapped to increase nest success of clapper rails, northern shrikes, and snowy plovers. Feral cats are also trapped to benefit the survival of riparian brush rabbits and the majority of the general public and wildlife biologists don’t object.

The more experienced duck hunter may be content with relatively fewer opportunities to shoot ducks. However, the only way we can recruit new hunters and waterfowl biologists is to give them more ducks to harvest. California has great potential to produce ducks and help perpetuate our great tradition of hunting.