Here I thought the Scaup were done with their northward migration at the end of March. And indeed in the last week of the month, only about a dozen laggards still remained, and those were gone by the weekend. But then in the first week of April, a new wave appeared overnight. They stretched the full length of the North Basin, many hundreds strong, almost all asleep, socially distancing. Where they came from, nobody knows; possibly from as far south as Baja California. Where they are going is clear: up to the Arctic tundra in northern Canada and Alaska — a vast set of marshes and lakes now emerging from winter. The birds’ return flight from here may cover some 2,000 miles or more, depending on their route. The North Basin is a rest stop on the way.
The birds’ northern summer breeding grounds are undergoing “some of the most rapid and severe climate change on Earth” (Wikipedia). Specifically,
The Canadian Arctic shows a decrease of snow coverage, glacier formation, permafrost and ice caps; increase in temperature; increase in precipitation; and, shrinking of lakes and wetlands over the past few decades. Additionally, gradual movement of the boreal forest – tundra transition zone in a northward direction is occurring and is expected to continue.
The lakes and wetlands, along with the vast insect populations they harbor, are vital for the Scaup and for many other species of birds that breed there and raise their young. According to a climate change map prepared by the Audubon Society, Scaup have already lost a huge summer territory in the far north. The numbers we see here now may seem impressive, but they are thin compared to the tens of thousands of Scaup whose nocturnal migrations a few decades ago could darken the full moon.
Update April 7: In the morning of April 7, not a single Scaup was to be seen along the whole stretch of the North Basin. Only two females and two males hung around in the immediate vicinity of the Schoolhouse Creek outfall in the southeast corner of the cove.
Update April 8: Once again there were hundreds of Scaup in the North Basin. Were these new arrivals, or the April 5 crew coming back after a detour further north into the big bay, as they’ve sometimes done in the past? See this video, showing only part of the assembly: