Hatching is finally over with one very late egg hatching today after having been incubated for 34 days; 28 days is normal. The oldest nestling is 16 days old; the chick is gaining weight and doing well like all of the other 45 nestlings.
While the main pack ice is well offshore, the Marginal Ice Zone, where ice covers from 18 to 80 percent of the ocean’s surface, extends south to the entire Alaskan Beaufort Sea coast, including Cooper Island. The seascape visible from the north beach now has widely scattered floes, some with rather high vertical relief breaking the horizon, in a nearly flat calm sea. This differs greatly from what was present last year when the first week in August had no ice visible with large swells breaking on north beach. More importantly, last year at this time the sea surface temperature was well above 4 degrees Celsius while this year it is less than 2 degrees Celsius. The guillemot’s preferred prey, Arctic Cod, are typically found in waters from -2 to 4 degrees.
The ice and water temperature conditions are ideal for the parent birds provisioning. Arctic Cod has comprised well over 90 percent of the prey being fed to chicks this year. The two oldest chicks, hatched on July 21, weighed 35 grams at hatching and now weigh 275 grams and 245 grams – the larger of the two experiencing an almost seven-fold weight increase in a 15-day period. A growth rate that rapid requires readily available prey that is both abundant and high energy, as well as two dedicated parents to return to the nest site with a fish every hour. Similar high growth rates are occurring at other nests.
This condition of the nestlings could not be more of a contrast with early August last year. Then, there was widespread mortality of younger siblings as parents could only find enough prey to maintain a single nestling. Arctic cod were absent for much of the nestling period with sculpin and juvenile sand lance comprising most of the prey. Guillemot parents turn to these alternative prey only when Arctic Cod are not available. Sculpin, with their large bony and spiny heads, are hard for nestlings to hold and swallow. They are frequently rejected with numbers building up in nest sites as the young wait for a more preferable fish.
For the moment our daily nest weighing and measuring of guillemot nestlings has been a very positive experience. However, based on what we have seen in the last decade, we know that conditions can change rapidly in August. A strong south wind could move the ice well out of the guillemots’ foraging range or warmer waters could move eastward from the Chukchi and drive away Arctic Cod. We also know that larger and older nestlings are more able to survive changes in prey availability and that the current high growth rates will allow more individuals to survive to fledging.
Science writer Jenny Woodman of Proteus writes about Cooper Island research and the current field season.
George Divoky frets–with good reason. In 2016, CNN Correspondent John D. Sutter called him the man who is watching the world melt. The description is as distressing as it is apt.
George sends us regular dispatches from a small field camp on Cooper Island, about 25 miles east of Utqiaġvik, where he has studied a colony of nesting Mandt’s Black Guillemots for the last 44 years. Since his work began in 1975, the research has morphed into one of the longest-running studies of seabirds, sea ice, and climate change.
Guillemots look like small penguins headed off to a fancy party replete with ice sculptures and all-night dancing. Unlike other seabirds that migrate out of the region seasonally, they live out over the frigid waters year-round, only returning to land to breed and fledge their young–this makes them an excellent indicator of how climate change is impacting the Arctic.
Weather delayed the start of this research season in early June. While warm temperatures in the Arctic have made headlines in recent months, unusually late snow and ice kept the guillemots from reaching their nesting boxes until mid-June; the first egg was laid on June 24.
His communications are tinged with an effort to buoy spirits–I’m guessing his own more so than ours. This week, the bad news came first: a 29-year-old female died. He wrote that she had been banded during the first George Bush administration. (While many humans rely on a simple Gregorian calendar, George’s memories appear to be synchronized according to a timeline rooted firmly in geopolitics.)
Bad news was followed with happy; two siblings from the 2014 cohort returned and recruited partners for breeding.
Otherwise, it’s been a stormy week on the island. On July 20, he wrote that the wind was finally dying down. A bad week for the infrastructure, the camp’s weather station was blown over and part of the heavy-duty WeatherPort tarp separated from the frame, which caused a number of things to get wet. On Wednesday he saw record high rainfall for that date.
Egg laying hit an all-time low this year, with fewer breeding pairs than any previous year.
He’s asking questions about how changing ice conditions will impact these seabirds – his seabirds. In his most recent field report, he spoke at length about the relationship between the guillemots and nearshore sea ice. The location of the sea ice impacts how far parents will have to fly to access suitable prey for their chicks. Increased travel time means greater energy expended by parents – for seabirds that live predominantly out in open waters, it’s all about balancing resources and energy. The presence or absence of sea ice combined with the temperature of the ocean waters impacts the availability of Arctic Cod, the small nutritious fish the guillemots prefer.
George hopes the slowly departing nearshore sea ice will keep ideal prey in foraging range for the seabirds. He wrote, the cod is “urgently needed for the colony to reduce its current population decline.”
David Douglas is a research wildlife biologist for United States Geological Survey (USGS) Alaska Science Center; he and George are frequent collaborators. This week he emailed the MODIS images displayed above and wrote that Cooper Island was pretty well surrounded until July 16 when the persistent ice immediately around the island broke up and melted.
Studies like George’s will help scientists to better understand the ramifications of long-term warming and less sea ice for wildlife in the region. Impacts to wildlife will directly affect the lives of the people who depend on subsistence fishing and hunting for survival.
Warming Arctic conditions have persisted with 2018 reaching record lows for sea ice extent, according to a report published by NOAA and University of Alaska Fairbanks’s International Arctic Research Center.
Late ice formation and early retreat in the Chukchi and Bering Seas impacted local communities by making travel for subsistence hunting and fishing dangerous and, at times, impossible. Storm damage and erosion was worsened by exposed shorelines, left unprotected by a lack of sea ice. Island villages and coastal communities experienced flooding and property damage as well. You can read more about the storm impacts here and here.
The report attributes late and minimal ice coverage to warmer temperatures, particularly over the last four years. Increased temperatures combined with stronger storms helped break up weaker ice.
In 2018, there was less sea ice in the Bering Sea than any year since 1850, when commercial whalers began recording this data. Experts agree, loss of sea ice is a result of climate change. Continued warming creates a feedback loop where warming temperatures melt ice; without a reflective snow and ice covering, the ocean absorbs more of the sun’s warming rays and temperatures continue to rise.
As for future winters, what can people expect to see if warming continues at current rates?
“Communities need to prepare for more winters with low sea ice and stormy conditions. Although not every winter will be like this one,” concludes the report, “there will likely be similar winters in the future. Ice formation will likely remain low if warm water temperatures in the Bering Sea continue.”
And for George’s seabirds? How many birds will successfully fledge this year? How many will return next?
Over most of its range the Black Guillemot is a nearshore seabird, occupying coastal waters during both the breeding and nonbreeding seasons, as do other members of the genus Cepphus. Pelagic or open ocean waters can offer abundant prey resources, but these options are often distant, patchy and unpredictable.
The nearshore typically offers seabirds a smaller but more reliable source prey base consisting of forage fish and benthic fauna from the ocean floor such as crustaceans or mussels.
The Arctic Ocean has extensive sea ice cover in the nearshore for the majority of the year; this presents a number of challenges to a nearshore species. Our work on the Cooper Island Black Guillemots has revealed a number of ways in which the species has met these challenges.
The current view from my cabin window illustrates one of the major problems guillemots face in the Arctic. Sea ice extends from the north beach of the island to the horizon and covers Elson Lagoon to the south. The only water available to the guillemots is a brackish pond in the center of the colony that provides no prey but is deep enough to provide sanctuary if the guillemots need to dive when pursued by an owl or falcon — regular visitors to the island.
While guillemots arrived on the island almost a month ago and egg laying is now complete, until recently the closest predictable open water where guillemots could find prey was approximately 20 miles away, off Point Barrow where winds and currents shift the sea ice creating an area of open water. This opening is called a lead. The Cooper Island guillemots stage there in April and May before coming to the island. (Editor’s note: Leads are important for wildlife, because they allow for access to oxygen in the case of seals and walruses and prey in the case of seabirds; you can read more from the National Snow and Ice Data Center here.)
This distance between the Cooper Island guillemots’ nesting colony and access to their prey resources during egg laying and incubation is in sharp contrast to what guillemots breeding in subarctic or temperate waters find at their breeding colonies. These birds occupy waters directly adjacent to colonies well before egg laying and foraging areas may even be within sight of nests. The birds breeding on Cooper Island (and likely all colonies of Mandt’s Black Guillemot Cepphus grylle mandti, the high Arctic subspecies of Black Guillemot) have responded to this spatial disconnect by having a well-defined periodicity in their daily colony attendance. Every day, the parent not incubating eggs and all nonbreeding individuals vacate the colony from approximately noon until midnight. The birds fly individually or in small groups to open water where they can feed for almost half the day before returning to the colony just as the “midnight sun” is at its lowest point in the sky.
MODIS image from July 9; snow and ice have blue/cyan color, while clouds will be lighter gray/white. Image Credit: David Douglass/USGS
While it seems individual birds could fly offshore to open water to feed anytime during the day, there are a number of possible reasons the observed colony-wide pattern of attendance and abandonment developed. For the half of the day when the guillemots are absent – from approximately noon to midnight – there is no evidence that Cooper Island supports a colony of Black Guillemots. It appears to be just a barren sandbar that happens to inexplicably have 200 scattered black plastic cases along with a small cabin surrounded by a bear fence. Falcons, Snowy Owls, and other predators moving along the barrier islands would have little reason to be attracted to this place.
The timing of the birds’ departure and return may be related to changes in air temperature and its effect on ice formation. On nights when the air temperature is below freezing (as it was last night), I have frequently observed the formation of new ice on the surface of the few spaces of open water in the sea ice directly adjacent to shore. This newly formed ice melts in the morning as air temperatures rise. Nocturnal formation of new ice in the waters adjacent to the pack ice reduces the amount of open water available for guillemots to dive for the prey.
This temporary daily reduction in foraging area could be expected to have been pronounced during the Last Glacial Maximum when air temperatures were lower and the ancestors of the Cooper Island guillemots occupied an Arctic refugium. The current pattern of colony attendance for the Cooper Island colony – foraging during the warmest part of the day and attending the breeding colony at night – could have evolved as a way of maximizing the amount of open water available for guillemots.
The large expanse of shorefast ice north of the island this year is persisting later than expected compared to recent years. While the nearshore ice may now be forcing the Cooper Island guillemots to fly further in search of prey, it could benefit the colony later this summer should ice remain in the nearshore close to the colony. In recent years a lack of sea ice when the guillemots are feeding young resulted in increased nestling mortality as higher sea surface temperatures reduced the availability of Arctic Cod, the guillemots’ preferred prey.
Should this year’s nearshore ice break up slowly over the next month, Arctic Cod could remain in the guillemots’ foraging range and allow increased chick growth and fledging success. The latter is urgently needed for the colony to reduce its current population decline. First eggs will be hatching in about two weeks and our daily weighing of nestlings and prey observations should demonstrate how much this year’s persistent sea ice has affected the guillemots’ nearshore environment.