Why are Wintering Migrant Goose Numbers Declining?

 

Research of both migrant and resident goose populations throughout the Atlantic flyway has shown that declines in wintering numbers may be linked to changes in migration timing and destination.  These changes are causing a decline in wintering goose populations in the south,
while wintering populations in northern states are increasing. This is referred to as the "short-stopping" of geese in the northern parts of the flyway because it is believed that migrating geese
 are developing a tendency to stay in northern states for the winter.


The SJBP Management Plan, which is written by the Atlantic Flyway Council, suggests that the timing and destination of migration for these geese may be influenced by the onset of more mild winters in recent years, changes in farming and land use practices across the country, or increases in the population size of temperate-nesting or resident geese.  For example, mild winters may cause SJBP geese to migrate later in the year than normal and/or to migrate to a different location.  So, while we are seeing a decrease in the population size of SJBP here in South Carolina, their numbers are increasing in areas of the Great Lakes.  Furthermore, if certain areas of the Great Lakes are experiencing more mild winters compared to earlier years, birds may remain in that region rather than expend energy to migrate further south. 


Goose migration may also be affected by changes in land use practices; specifically the availability of cereal grains both here in the south as well as along the migration route.  For example, if an ample supply of winter forage is available in northern states, there is no need for geese to migrate further south.  Also, if geese return to a known crop field in SC, and find that food resources and habitat are missing, they may be forced to find a different wintering ground.  There is no doubt that farming practices, both here in SC and in northern states, are constantly changing.  Not only is farmland changing, but the abundance and configuration of residential and commercial land is changing as well.  Evidence suggests that SJBP birds feed and loaf on areas adjacent to the refuge which are currently targeted for development. Another factor to consider is the amount of waterfowl management areas available to waterfowl in the northern and southern parts of the country. Overall, the degree of waterfowl management in the north is greater than in the south, which could explain why geese are choosing to winter there.

It is also possible that goose migration may be affected by the population size or habits of the resident goose populations.  Resident geese are those that do not take part in a seasonal migration to separate breeding and wintering grounds; instead they remain in relatively the same area throughout the year.  According to the SJBP Management Plan, resident geese may draw or attract SJBP birds to non-traditional areas, which can cause delayed migration timing or may cause birds to remain further north. According to various waterfowl surveys throughout the United States, Canada geese show a population increase of 3 to 10% from the 1950’s to the present day.  The overall population trend for geese suggests an increase in the resident populations, and decreasing or stable populations of migrant birds.  These trends also show an increase in goose numbers in northern states and a decrease in numbers in southern states. If resident geese draw or attract migrant birds to non typical areas, we could possibly see an increase in this occurrence as resident goose populations increase. Various hunting regulation changes and season changes have been made to combat population growth of resident birds, especially since large flocks of birds can become a nuisance to some landowners and businesses.