Animals in the Arctic are shifting their behavior to keep pace with climate change. The research is based on data collected from more than 200 studies which tracked the movements of thousands of Arctic animals over the last three decades.
The database combines the work of ecologists from all over the world. Study co-lead author Gil Bohrer is a professor of Civil, Environmental, and Geodetic Engineering at The Ohio State University.
“What we ended up with is this massive dataset that can tell us how the behavior of animals is evolving in the face of climate change,” said Professor Bohrer.
In the Arctic, the average temperatures have increased about 2.3 degrees Celsius since the 1970s. The researchers found that the cumulative effects of earlier springs, warmer winters, melting sea ice, and human development have transformed the behavior of native Arctic animals.
Professor Bohrer said that collecting the data in one place was important. Without the database, it would be difficult for scientists to quantify the long-term effects of climate change and human activities on Arctic animals.
“Ecologists are doing the best they can, but often, movement track data would be lost – researchers retire or move to other positions, the hard drive ends up getting lost, the research notebook is misplaced or thrown away, and then that data is gone,” said Professor Bohrer. “And animal tracking is very hard to do, so a research project might cover a handful of animals, maybe 10s at the most. Each animal-movement tag costs hundreds — and sometimes thousands – of dollars, and you need to catch the animal and follow it. It’s a lot of work and a lot of money.”
Three separate analyses of the data show large-scale shifts in the movement of golden eagles, bears, caribou, moose, and wolves. The behavioral changes could impact the ability for these species to eat, mate, and survive.
The first study compared the movements of more than 100 golden eagles from 1993 to 2017. The experts found that immature birds migrating north in the spring arrived to the region earlier after a mild winter, which suggests that warmer temperatures are prompting the eagles to migrate sooner. On the other hand, adult golden eagles did not change their migration patterns. According to the study authors, this could have consequences for nesting and chick survival.
The second analysis tracked more than 900 female caribou from 2000 to 2017. The study revealed that northern herds are giving birth earlier in the spring, while the calving dates of southern populations have not changed. The early spring is associated with more extreme variation in weather patterns, posing some serious risks. For example, heavy snowfall events in the late spring snow could be fatal for calves born earlier in the season.
The third study monitored the speed of bear, caribou, moose, and wolf movement from 1998 to 2019. These species were found to move at different speeds depending on seasonal temperatures and precipitation. The investigation revealed that moose and caribou moved more in days with higher temperatures, while their predators moved less. The findings suggest that it will be more difficult for herbivores to avoid predators as temperatures continue to rise.
“I’m really excited about how this work shows what you can learn from comparing data across populations on a very large scale,” said study co-author Elie Gurarie of the University of Maryland. “I would say this is an early example of what we might call global animal movement ecology. We’re increasing our ability to monitor the pulse of animal populations across the Earth and ask big picture questions about what it means.”
“This work has given us a baseline to understand the large-scale picture so we can get a sense of how animals and environments are really interacting across species and across space as the environment changes.”
The study is published in the journal Science.