If you spend any time near the Fraser and Skagit River deltas, you may have seen Snow Geese (Anser caerulescens) with orange faces. These individuals are significant when it comes to protecting the largest and most important estuary in British Columbia, and not just because of their unique coloration.
The orange stains occur when the geese forage on bulrush and sedge rootstalks in iron-saturated muds of the Fraser River Delta marshes. Research Scientist Dr. Sean Boyd of Environment and Climate Change Canada shares why these stains are part of a much bigger picture, and how the Snow Geese may be impacting the health of the estuary.
Each winter, Snow Geese fly from their summer breeding grounds on Wrangel Island in the Russian Siberian Arctic to their overwintering grounds on the Fraser River Delta. Since the mid-1970s, the number of geese wintering on the delta has increased almost 10-fold, from around 7,000 to over 60,000. The increase in the populations and associated increase in foraging pressure has led to a decline in plant density and concentration and, in some places, the conversion of marshes to mudflats. Using the orange stains as a reference allows researchers to identify which Snow Geese are using the Fraser River Delta as overwintering grounds, and which aren’t.
Dr. Boyd has been monitoring Snow Geese and marshes in the Fraser River Delta for over 30 years. Data shows that bulrush biomass has declined by over 50% in the Delta, impacting not only Snow Geese, but other species like ducks, Trumpeter Swans (Cygnus buccinator), and juvenile Chinook Salmon (Oncorhynchus tshawytscha). This spurred Dr. Boyd and colleagues to further investigate the foraging patterns and habitat use of Snow Geese along their migratory routes.
In March 2023, the researchers tagged 10 Snow Geese. Of those 10 geese, one individual, ‘X17, a male’, is providing detailed insight into his travels between the Fraser River Delta and Wrangel Island. After departing from the Fraser River Delta in April 2023, X17 made its way along the Pacific Coast, stopping occasionally to refuel, including a shot stop atop a glacier near Anchorage, AK. Fifty days later, the X17 arrived on Wrangel Island, where he spent the spring and most of the summer. On August 15, X17 left Wrangel Island for his wintering grounds at the Fraser River Delta, arriving 50 days later on October 5th, 2023. The researchers were also able to determine that X17 likely did not breed, given its continuous movement on Wrangel Island and early arrival to the Fraser.
Animation showing the flight path of X17 in the Fraser River Delta. Video: Dominic Janus
While this research is ongoing, the data are already revealing important information about the study species. Recent data shows X17 moving around the Fraser River Delta, traveling between different tidal marshes and inland to farms at night to feed. The movements of X17 are significant because they represent the patterns of the 1,000s of other Snow Geese traveling in the same flock, highlighting the potential impacts on the marsh.
Overall, this research enables the team to understand in detail how Snow Geese are using the Fraser River Delta and how this is impacting the tidal marshes. Ultimately, this study and the continued tracking will help managers and researchers make better decisions on how to manage both the geese and the Fraser River Delta going forward.
