AUTHOR BLOG: Lifting hunting limits hasn’t solved the Snow Goose overpopulation problem

Robert Rockwell

Linked paper: Liberalized harvest regulations have not affected overabundant Snow Geese in Northern Manitoba by D.N. Koons, L.M. Aubry, and R.F. Rockwell, The Condor: Ornithological Applications.


A large flock of snow geese during spring migration in North Dakota. Photo by Craig Bihrle, North Dakota Game and Fish Department.

As many marshes along the Gulf Coast were drained in the late 1970s, Snow Geese that had used them as wintering areas began shifting to agricultural land instead. Leftover crops in farm fields provided them with a generous new winter and spring diet, and the population began growing at an unprecedented rate. While they have ample habitat in the south, the growing number of geese, coupled with their destructive foraging behaviors, has led to increasing and widespread habitat destruction in the Arctic coastal habitats where they breed.

In response to this habitat degradation and the resulting negative impacts on other species, the U.S. and Canada attempted to reduce the size of the population by liberalizing the regulations on Snow Goose hunting beginning in 1997. This included increasing bag and possession limits, expanding the hours during which hunting is permitted, allowing the use of unplugged shotguns and electronic callers, and instituting a spring conservation harvest. Adult mortality has a greater relative impact on the growth rate of this species than any other demographic variable, so wildlife managers hoped that removing more adults from the population through hunting would help bring it under control.

Severely degraded coastal and near-coastal habitat in Wapusk National Park outside of Churchill, Manitoba, Canada. Photo by Stephen Brenner, Nebraska Game and Parks Commission.

Adaptive Harvest Management is an approach used in North America that examines the impacts of management decisions and readjusts those decisions as necessary to meet management goals. We used our 50-year database on more than 100,000 Snow Geese banded on Canada’s Cape Churchill Peninsula to assess whether the new regulations were having the desired effect of increasing adult mortality. Using new analytical techniques, we could estimate the rates of both hunter and non-hunter deaths of adult geese and see whether those rates changed when the new hunting regulations were implemented.

Adult harvest mortality has stabilized at a low level, with only around 3% of adult geese being killed by hunters in a given year, probably because the sheer abundance of Snow Geese in this population has overwhelmed the number of hunters. The number of North American hunters has not increased in recent years, and most hunters are only willing to harvest enough geese to meet their family’s needs. Adult non-harvest mortality declined through the 1970s and 1980s to trivial levels (around 1% per year), but has increased recently and now fluctuates between 10% and 19% per year. Unfortunately, the combined mortality isn’t enough to limit the species’ growth, and the population continues to increase in size.

In light of our results, the next cycle of Adaptive Harvest Management needs to consider the potential causes of the increase in non-hunting mortality and its year to year variability, especially since such variation actually reduces overall population growth rate. We also suggest that management agencies further refine hunting regulations to increase the harvest per hunter and make efforts to increase public participation in hunting, perhaps through outreach to currently underrepresented groups.

The authors are all associated with the Hudson Bay Project. More about our work can be found at http://research.amnh.org/users/rfr/hbp.

3 thoughts on “AUTHOR BLOG: Lifting hunting limits hasn’t solved the Snow Goose overpopulation problem

  1. Hunting bird limits and methods need to be all out liberal to help out and could possibly decrease some of the over-population of Snow Geese. I have always seen a need for this. Why are there birds limits and method limits at all during hunting season? Doesn’t make much sense to me considering the amount of Snow Geese available to hunt.

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  2. I live in eastern Nebraska and was frustrated in early January when we had many opportunities to harvest more snowgeese that were late migrators from the north. Our snowgoose season was closed from Dec. 26 thru Jan. 12th. We asked our local game warden why this was closed and he said federal law states snowgoose season can only be 107 days long so they had to split it to able to keep it open until April 15th in case the spring migration was running late. If the feds would allow a longer snowgoose season longer than 107 days then we could harvest a lot more birds. Open snowgoose season in October and leave it open thru end of spring season would be helpful for us snowgoose hunters to harvest more birds here in Nebraska

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  3. It’s hard to keep the population in check when they are so Refuge orientated. In my area in Iowa there are 7 refuges within a 150 mile stretch right in their flight path and the refuges are closed to hunting! If they would open the refuges to hunting snow geese only that would disperse them into smaller flocks and keep them moving around instead of piling in on a refuge in sitting all day that would give Hunters more of an opportunity. The snow geese in my area when they come through know where they can go to and be safe!

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