New data analysis indicates that the North American black brant goose is developing a shift in migration patterns. Previously, the Arctic members of the species, Branta bernicla nigricanis, were known to overwinter in Baja, California. A new study by a recent APU graduate, Toshio Matsuoka, 21, indicates that the North American black brant can now be found as far North as Izembek, Alaska, during the winter season, which is a 25-degree change in latitude from the birds’ usual winter home. Izembek, a region along Alaska’s panhandle with flat lands and surrounded by waters, has acted as a staging point during fall migration season, rather than a winter dwelling, leading some researchers to describe the migration shift as “unprecedented.”

DebKurtzGoose provided by Deb Kurtz at the National Park Service

“There’s this one breeding population for these birds on the Yukon Kuskokwim Delta that previously represented over 75 percent of the total breeding population of the black brant bird species, and that population has been declining,” said Matsuoka as he sat in a chair in the APU lobby. Music was drifting in from the nearby coffee cart. “It’s the population in the Arctic coastal plain that has been increasing, so you have these diverging population trends.”

While both of the populations have a declining survival rate, the differences between the two populations indicate that something could be occurring during the non-breeding season that’s affecting survival. These occurrences could be tied to habitat or where the birds overwinter, which is why researchers at the United States Geological Survey decided to gather data on the migration patterns of the birds from 2011 to 2014. Initially, the project was meant to fill some gaps in the understanding of black brants, which serve as an Indigenous subsistence source, but the data revealed new information. The results pointed toward how changing climates create large-scale modifications in animal behavior.

Matsuoka, a calm presence with dark hair and wire-frame glasses, originally began his work with USGS in 2022 as a science communicator for the Alaska Science Center. In 2023, he moved to analyzing black brant migration for his senior project with advising from APU Professor Pam Maslyk and his USGS supervisor Vijay Patil.

“I always enjoyed learning cool science facts when I was growing up,” Matsuoka said, explaining that the expansion of the “human knowledge flow” was an early dream of his. Nowadays the bigger draw toward science is the way research can be used to recognize and mitigate problems in the world.

Matsuoka began studying data collected using a sample of more than 60 tagged birds carrying small light sensors that recorded the rising and setting times of the sun. The timing of daylight hours could then be translated into locations, showing the areas that birds congregated during different times of the year.

To analyze the data, Matsuoka spent hours at a laptop computer with extra monitors in his office, working with the coding platform RStudio, an industry standard. He first learned R during APU’s earlyhonors program when he took a statistics class with Professor Roman Dial. Throughout his work, Matsuoka checked previous literature on both black brant migration patterns and coding methods for guidance, as it ensured the project would provide useful results. Matsuoka said, “it’s primarily me sitting down and being like, okay, what’s a reasonable way to think about this, just trying it, and reviewing the literature and seeing what’s out there.”

The results only provided a “coarse” location estimate. The light data provided about a 250 km buffer for the exact location of the tagged bird, which means that any individual bird in the study could have ventured up to 155 miles from the pinpointed location of the sensor. However, when the information is reviewed on the scale of the black brant’s migration routes and compared with previously known information of their overwintering areas, the estimates are accurate enough to show how patterns are changing.

Matsuoka learned that from 2011 to 2014, 42 percent of the Arctic population of black brant were overwintering north of Baja, which underscores the evidence pointing to the increasing Arctic population. Included within that 42 percent are the 32 percent that are now found in Izembek during the winter.

Compared with data from 1987, there was also a shift in arrival times for these birds, with Arctic populations arriving at Izembek earlier than they did in 1987. This is one of the key potential indicators that the climate could be affecting black brant behavior.

Matsuoka is continuing his work at USGS as a physical science technician, working to find further answers about black brant migration.

“During my senior project I got to this point where I was like, okay, here’s where the birds went,” Matsuoka said. “Now what we’re looking at is when the birds come back to the breeding site—does it pose benefits at the breeding site for choosing to overwinter at the Alaska site versus Baja?”

Expertise in R, often used for computing statistical information and graphics, was only one takeaway from the project for Matsuoka. “When you go into your undergrad, you’re kind of just spoon-fed information,” Matsuoka said. The APU senior project is a glimpse into work beyond.

“A lot of it is independent education for yourself, and that’s a difficult transition,” Matsuoka said. Yet he found the self-led process of the senior project to be rewarding, saying, “Being able to be independent, and do the work, and get it done—I have a good feeling.”

Article written by graduating student Laura Ditto as part of her senior project, Science in Progress: Reporting on Research at APU.