Changes in Latitude
Shawn Swearingen for SPLIT REED
Cover Photo Courtesy of Ryan Askren
They go by a lot of names, some endearing and some not so, by those that chase them. By the regulation books, they are known as Anser albifrons, or Greater White-Fronted Geese. Chances are you have also learned how there are just as many theories on why the migration patterns are moving as well. Current research being done as part of the Osborne Lab at the University of Arkansas - Monticello, relies on band recovery data with bird transmitter data that together are showing just what hunters have observed.
Art Diaz
The Osborne Lab recently shared a fascinating time-lapse of white-front band recoveries through time on the social media platform, Instagram. The interactive map, created by Callie Moore as part of her Master’s research, shows in real-time how the wintering grounds for white-fronted geese have moved. The time-lapse starts by showing white-fronts historical wintering grounds occurring in Texas along the Gulf Coast. This area was used almost exclusively by the geese until the early 1990’s when banding data shows recoveries began increasing in locations within the Mississippi Alluvial Valley of Arkansas. How exactly were they able to piece this together?
In talking with Ryan Askren who has been studying white-fronted geese using satellite transmitters with the Osborne Lab, this time-lapse is based on band recovery data of the geese. The white-fronted goose band recovery dataset goes back to the 1960s, but statistically sufficient numbers of band recovery didn’t occur until 1976 with 43 bands. The following year 84 bands were reported and continued to increase through the years, Banding efforts have increased over the decades leading to about 400 and 600 white-fronted goose bands being recovered each season. This is a lot of data points for researchers to utilize.
Art Diaz
Where the transmitters come into assistance is seeing exactly what this draw might be for the geese and causing the large-scale population shifts. “The purpose of analyzing transmitter data was to look at habitat selection, due to concern of depredation on winter wheat and competition for food sources by white-fronted geese with other waterfowl following the shift in winter distribution,” comments Ryan. What they have found is selection for rice agriculture currently and changes to rice production, for various reasons, from Texas to Arkansas and the Mississippi alluvial valley, suggesting changing white-front distributions are related to shifts in rice. “Historically, white-fronts and snow geese were wintering along the Gulf Coast in Louisiana and Texas, feeding on tubers and seeds of natural vegetation. However, like most species of geese, white-fronts are highly adaptable in what they eat and have done incredibly well feeding on agricultural grains.”
Ryan Askren
These pattern shifts haven’t only been noticed in white-fronted geese, but also in Ross geese shifting from traditional wintering in California to now include the Gulf Coast and Mississippi Alluvial Valley. “Anecdotally, hunters and biologists have witnessed shifts in Canada goose distributions over recent decades, from places like southern Illinois or Sumner, Missouri to more northern areas, like the suburbs of Chicago. Even in Europe, populations of pink-footed and barnacle goose have shifted wintering distributions, following changes in agricultural practices,” notes Ryan.
The critical results from these studies help state and federal wildlife biologists better construct hunting regulations. Additionally, it helps hunters like us realize that when we ask “Where did the birds go?” there is someone looking for an answer. As Ryan observed, “Understanding the ‘how’ and ‘why’ affects hunter recruitment and opportunity.”
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