It is one of the oddest relationships in birds: Wherever a migrating Arctic albatross falls, the female appears to head for the Great Lakes to seek refuge in the ocean. But new research suggests that such common locations may be the exception to the rule. They may only occur because climate change is forcing populations to split up into a fewer number of “sisters.”
Locating the migrating species helps researchers estimate the population of the birds. No matter where they fall, migrating albatrosses are often located within an area referred to as a “spot.” This information can be critical to scientists’ understanding of populations, because it is the size of the distance that a female albatross migrates that serves as a proxy for how many sisters the species has.
The study, published Wednesday in Scientific Reports, looked at the migration patterns of 190 migrating albatrosses, each of which was tracked with a global positioning system. Migrating albatrosses, which are among the most studied animal species in the world, typically migrate across the northern polar regions, from east to west and from south to north.
But, for the scientists, there was little reliable information about how far migratory albatrosses traveled. One possible reason for this is that some species just aren’t as reliable at estimating where they’ve flown.
In the study, however, the scientists looked at the actual distance those albatrosses traveled by satellite. The team used satellite data from satellite navigation devices from 30 years back to estimate the distance across the Arctic, and also how far the birds traveled by satellite in 2018.
They found that of the 189 migrating albatrosses, only nine (a very small number) used the satellite navigation systems that led them on their migrations, while another 37 have not used these devices at all.
They found that migrating albatrosses are following a very familiar route and that these flights are nearly identical to the satellite flights they took a decade ago.
In fact, there were some notable departures from this typical migration flight. The scientists said it seems that migrants in some cases are making “split-offs” from the ancient three-way migrations where the flying females often took a curved route. They appeared to follow the same journey in 2012 but one year later, in 2014, were all following the same three-way migration route.
The study said the satellites show that the remaining migrating birds mostly tend to fly in pairs. But their relationships aren’t all rosy.
The large non-migrating albatrosses not only followed a very similar one-way route, but made it nearly to the ocean at the same time as the migratory ones. Given that the scientists tracked their location, the annual population sizes of both species are almost definitely in decline.
There are still uncertain factors that could be linked to the frequency of separating migration flights and any effect on the reproduction rates of non-migrating albatrosses. However, the scientists said their conclusions are borne out by observations of the migration and cloud cover across the migratory species. The team noted that the most important role of the study is that it helps scientists understand how climate change has affected migratory birds and the dynamics between migration flights.
The scientists also said the study is important for understanding where the migratory albatrosses are.
Without the use of satellites, researchers had little information about the sea ice conditions that may have driven some birds to either find their way home or remain in the sea. The scientists were able to do so, however, because a study several years ago found that climate change can have dramatic effects on sea ice conditions along the Arctic coastline and the migratory routes associated with the sea ice.
“Our new data show how technology makes it possible to observe dynamic relationships between populations as they are changing,” the authors of the study wrote.