The Overpopulation of the Snow Goose in North America
The purpose of this paper is to explore available research on the overpopulation of the Snow Goose on the North American continent. The snow goose has been rising in population since the middle of the century and has been escalating so much it is destroying their natural habitat. Wildlife managers have just recently begun to implement strategies to combat this problem. Mainly through the use of hunters the managers are trying to curb the population growth.
There are three main species of Snow Goose of primary concern. The Lesser Snow Goose (LSGO) is the must abundant and at the same time most troublesome. Ross’ Goose (ROGO) is very similar to the Lesser and can only be distinguished by close observation. Both the Lesser and the Ross nest in salt marshes along Hudson Bay and then migrate down to the gulf coast states such as Texas and Louisiana. Their populations number in the millions. The third sub species is the Greater Snow Goose. They nest in the same marshes as the others except they migrate down the Atlantic Coast into the Carolinas and that vicinity. All three species have exploded in numbers since the 1950’s. Researchers have done a lot of study on the numbers and the degradation but may need to do more studies on the impact to other species and look for other options to control the populations.
The numbers of all “light” colored geese has been on the rise since data was first collected. The Lesser Snow Goose (LSGO) has drastically increased in number since data was first taken. Numbers range from around 800,000 in 1969 to as many as 6 million in 1996 (CWS 1999). While the Greater Snow Goose (GSGO) has risen in numbers from a few thousand to almost 500,000 (CWS 1999). This brief article did not provide much insight into actual numbers. Abraham and Jeffries in their report dig deeper and provide more significant and detailed population counts. Their numbers add in the Mid-winter index, which is the number of geese counted during mid-winter and referred to as MWI. Their numbers also have a count for Ross’ Goose (ROGO) which primarily flies with the (LSGO) and is very hard to distinguish (Abraham and Jeffries 1998). They too suggest the LSGO population to be around 800,000 in 1969 and in 1994 about 2.4 million. Although it is suggested that the number is low due an undercount during the winter and a more precise count may be taken when nesting in spring. The population of Greater Snow Goose has reached 612,000 from around 50,000 in the mid 1960’s. Ross’ Goose has increased from 8,000 in 1957 to nearly 500,000 in 1995 (Abraham and Jeffries). The Texas Department of Fish and Wildlife states that the population of wintering snow geese has remained constant. They imply this is due to the fact that the geese have spread their winter range into other states (TWDS 1999). As indicated earlier it is very hard to count wintering birds because such a large number of wintering areas. Below are a few graphs of these population trends
Factors contributing to High Population
The snow goose problem is a wildlife manager’s nightmare. Through prudent restrictions on birds taken as game, and the increase in refuges coupled with excellent habitat in the birds entire range. It is estimated that there is nearly 900,000 ha of rice fields over the snow goose’s winter range (Abraham and Jeffries 1998). This is in addition to the typical salt marsh wintering ground. Abraham and Jeffries suggest that farther to the North in states like Nebraska and North Dakota the conversion of grassland prairie into cereal grains has provided a tremendous amount of food for the geese. In addition it has also blurred the area typically considered the wintering range. It may also provide a natural rest stop along the way for migrating birds assuring greater health at nesting grounds (Abraham and Jeffries 1998). The establishment of refugees has reduced the amount of birds taken by hunters allowing more birds to complete a full migration cycle (CWS 1999). Hunting of the Greater Snow Goose was banned in the us from 1931-75 (Abraham and Jeffries 1998). Hunting was not allowed to promote population numbers, and once started in 1975 did not have a high harvest. The LSGO and ROGO starting in the middle of the 60’s and continually have extended their nesting range south into less extreme climate (Abraham and Jeffries 1998). It has also been suggested that since birds are now living longer the older adults are now leading the less wary young to safer sites and out of hunter’s range (Ingstrup 1998). Ingstrup also suggests that the artic may be warming and as Abraham and Jeffries cited there has been shown a correlation between the snow melt and survival of nesting birds and their young. According to Hodge the annual kill by hunters in 1970 neared 40% but in 1994 the rate had dropped to less than 8%. Thus allowing a great deal of the adult population to return to nesting sites in the spring.
Impact on habitat
The snow geese still nest in a primarily salt marsh environment. The geese have a detrimental feeding behavior in which they pull up the marsh grass by the roots. This behavior is know as grubbing and when done in mass quantities can destroy whole marshes for decades. A project known as the “Hudson Bay Project: Ecosystem Studies and Conservation of Coastal Arctic Tundra” has done extensive research onto the effects of the snow goose population on the area around Hudson Bay. Researchers there estimate that it takes decades to replace a marsh that has been decimated by the geese. It has been shown by the Hudson Bay Project that repeated grubbing on the salt marsh in the Hudson Bay area has effectively depleted a large percentage of the available marsh. The geese completely strip the marsh of grass, and can ruin a marsh for a long period of time. The project researchers set up exclusion zones where they fenced off part of the marsh to demonstrate and measure the effects of grubbing and overpopulation on marshes. The exclusion zone would maintain green patch of grass while the rest of the marsh would become barren and undesirable (Hudson Bay Project 1999). Some have suggested they are damaging the crops in their winter range, but it is also known that a large portion of their winter food is waste grain, not a huge environmental impact as in their nesting grounds. It is estimated nearly 35 percent of their nesting territory has been completely destroyed and another 30 percent so badly damaged that is not viable and the remaining 35 percent is in grave danger of becoming wasted (Hodge 1999).
Exclusion zones showing marsh grass depletion. (Hudson Bay Project)
Degraded marsh. (Hudson Bay Project)
Impact on other Species
The impact on other species is the major whole I have seen in the research done to date, I had a real hard time finding any concrete evidence that the high number of geese was negatively affecting other species. The Hudson Bay Project and Hodge both claim that it is and will affect other species such as ducks and shore birds. While it might be easy to draw the conclusion that degrading of their habitat will send the populations into decline I just don’t see much hard evidence, and it would be nice in future studies to have a correlation between the increase in Snow goose population and a decrease in say the yellow rail population. Abraham and Jeffries make and excellent point “The scale of the problem and associated level of risk to the broader populations requires intensive study, including some calculation of the proportion of total range of the species affected by goose damage. It is clear, however, that the interaction is dynamic, and the rapid occupation of new areas by geese increases the threat to other species even as the effects are being calculated.”
The general consensus among many groups is that a very large percentage of the population needs to be eliminated. There are two main ways now that birds a killed. That is through aboriginal egging and Recreational hunting. The amount to which hunting is disputed (Paul 1999). Paul points to seemingly different numbers by two different groups each suggesting the recommended kill or harvest of the Snow goose. Mrs. Paul also points out that on the extreme end the harvest rate would have to increase by 9 fold to have the desired effect on the overall population. To have this desired effect the US and Canadian governments have agreed to expand hunting in hopes of nabbing more birds. Texas even has proposed a special permit for some hunters that would allow them to take as many as 100 more birds than they did last year. The Canadian government is also looking into ways to encourage aboriginal peoples to take more eggs for subsistence. States are being encouraged to do what is necessary to increase hunting opportunities for the Snow goose. Some are considering putting pressure on private land owners to allow more hunting. Refugee managers are also toying with opening up more hunting on previously denoted safe zones. Manitoba has opened up a special Lesser Snow Goose hunting season in the spring and allowed hunters to use electronic calls (CWS 1999). Electronic calls are thought to increase the chances for hunters.
Will it Work?
One of the main concerns for all involved is will it work? Paul stresses the point that we must consider if the strategies will allow for complete recovery of the grass. Should the Refuge system be modified? Are our practices for other migratory birds going to lead to similar problems? (Paul 1999) It is estimated that hunters will need to kill over 900,000 geese a year for over a decade to make any kind of dent in the population (Hodge 1999). Some are skeptical that hunters can take that many birds to begin with, let alone the fact that to many that seems like a merciless slaughter of innocent animals.
It appears that one thing is very clear there is an overpopulation of Snow Geese on the North American Continent. The situation is almost out of hand and something needs to be done fast. Although there has enough research on the fact that there are simply to many geese there really has not been enough on the impacts to other species, and what is the best way to take care of the problem. Both the US and the Canadian government seem to be on the right path to controlling this problem that humans have created. But more needs to be done. There just simply isn’t enough hunters around to take the proper amount of birds in a sporting manner. Wildlife managers are going to have to step in and take more radical measure to control this before its too late and we have lost all the habitat for the geese and all other habitants of the salt marshes of the Hudson Bay area.