Traveling Wildlife: Another consequence of the melting Arctic

Shore-fast sea ice in June on Alaska's arctic coast.

Shore-fast sea ice in June on Alaska’s arctic coast.

I’ve said it numerous times: the north is changing, and changing fast. As a birder, those changes are obvious. Shorebirds are being affected by melting glaciers, songbirds, and other boreal species are moving north with growing shrubs, fires are changing forests, and how birds use those habitats. But no place is changing as rapidly as the arctic.

I spend a fair amount of the summer in Alaska’s arctic. On many trips, I end up somewhere close to the Arctic Ocean, or at least get a view of that expanse from some Brooks Range peak. That big body of water, is, in all honesty, not something I know a great deal about. My familiarity ends with the land, or at least with what floats atop the water (think: ducks). The happenings beneath the surface, or on the sea ice, or down on the ocean bottom, are as incomprehensible to me as Mars. I’m not alone there, the Arctic Ocean is a tough place to study and there still isn’t t a lot known about it. But if there is one thing that has defined the Arctic Ocean’s ecosystem, it’s ice, and that ice is melting.

Multi-year ice, the stuff that has remained frozen for more than one full year, has practically disappeared, reaching its lowest extents ever in the past few summers. Single-year ice too is disappearing and is around for less time each year. All of this translates into an arctic coast that, for a few months each year is free of ice.

That loss of ice is creating some interesting changes in the fauna of the north. Species once isolated in either the North Atlantic or North Pacific by the persistent ice cover, are now able to move about freely across the northwest passage. The barrier is melting.

A crack in shore-fast sea ice with open water beyond in June, off the coast of the Arctic National Wildlife Refuge.

A crack in shore-fast sea ice with open water beyond in June, off the coast of the Arctic National Wildlife Refuge.

This phenomenon raises some interesting questions about conservation. We can do a lot to control how ships use this newly ice-free ocean, we can even regulate oil development, and do our best to minimize risks of spills (Note I’m saying we CAN do these things, not that we ARE.) But wildlife will go where wildlife wants, and for the first time in millennia, species that have been isolated are encroaching on one another.

To be honest, I hadn’t even considered this until recently, when a college friend of mine, Seabird McKeon, who is now a researcher at the Smithsonian, sent me an early copy of his paper on the subject (see the reference at the bottom). As a birder, I pay attention to vagrancy (when birds end up where they shouldn’t), but hadn’t noticed any particular pattern in the arctic. Turns out, I wasn’t paying as close attention as I should have; I’m glad Sea was.

It’s not just birds. Many species in the past few years have started to criss-cross the arctic. Bowhead Whales, for example, have both Atlantic and Pacific populations which have been separated from one another by ice. But, in 2010, two whales from separate populations were found foraging together off northern Canada in newly ice-free waters.

Not all interactions are as benign as the Bowheads experienced. Killer Whales, for the first time have been observed in Hudson’s Bay where they were seen hunting Belugas, Narwhal, Atlantic Bowhead Whales, and a number of seal species. Orcas were previously kept out of Hudson’s Bay by consolidated sea ice. No longer the case, these predators are now able to move freely, and their impacts could be big on the resident species of marine mammals.

Male Common Eider near the arctic coast in the Arctic National Wildlife Refuge, Alaska.

Male Common Eider near the arctic coast in the Arctic National Wildlife Refuge, Alaska.

Atlantic birds reaching the the Pacific and vis versa are another breed of Arctic interloper. Contiguous sea ice, is an effective barrier to fish-eating birds, and played an important role in separating the avifauna of the Pacific with that of the Atlantic. But as that sea ice disappears, birds are making that crossing with increasing frequency. Northern Gannets, an Atlantic species, have had a couple of recent sightings in the Pacific, including here in Alaska. Eiders, shearwaters, puffins, and auklets are all appearing outside their normal ranges.

So yeah, weird things are happening in the arctic. And this weirdness is leading to some novel conservation challenges. Species that haven’t previously come into contact with one another may soon have overlapping ranges, leading to competition that previously didn’t occur. What if, for example, Atlantic Puffins establish themselves in the North Pacific? And what if they are better at finding and defending burrows than our native puffins?

Species that have separate lineages may also come together more often. Common Eiders for example have a number of subspecies that were separated from one another by sea ice. Will we see hybridization between these as they come into contact? Probably.

Diseases too, already growing more frequent with warming temperatures, can now be carried between ocean basins. In new hosts, these pathogens could grow virulent, impacting populations.

So what do we do? As I noted, this exchange of species is not something land managers or policy makers can influence. It’s not like we can slam a fence over the arctic to keep out the immigrants.

What we are left with is science.

We need a baseline understanding of the ecology and populations of arctic species in both the Atlantic and Pacific, so we can measure how things are changing. And we need to know about breeding ranges and resource requirements so we can see how changes are likely to impact different species. This all needs to happen, and now.

The Arctic is still a scientific frontier and our knowledge of it is far behind that of many other regions of the planet. It’s time to change that.

The paper I used for this article is:
McKeaon, Seabird C. et al. 2015. Melting barriers to faunal exchange across ocean basins. Global Change Biology doi:10.1111/gcb.13116.