Category Archives: 2018 Field Season

2018 Census

In this week’s field report, George talks about specific birds as well as the overall report of his 2018 Black Guillemot census on Cooper Island.

Nature, when observed or monitored for any extended period, typically provides a predictability that is reassuring in its consistency and sufficient surprises to keep one engaged.

For over four decades, my first task after I set up camp was a census of the Cooper Island Black Guillemot colony. This year was an excellent example of this balance of the expected and unexpected.

Since the 1970s, the majority of the birds breeding in the colony have had, in addition to a numbered metal band, a unique combination of color bands allowing identification with binoculars of individual birds. My census of the colony consists of recording the number of occupied nest sites and the color band combinations of the individuals occupying each site. This allows me to determine the birds who survived the winter since last year’s breeding season and whether they have retained the same nest site and mate.

Colorful bands make it easy to identify familiar birds and newcomers (without bands). Image Credit: George Divoky

Black Guillemots, like most seabirds, have high annual survival of adult birds and high mate and nest-site fidelity. On average 90 percent of the individuals breeding on Cooper have returned the following year with mate and nest-site fidelity over 95 percent. With loss of breeding birds so uncommon and changes in mate and nest site so rare, past censuses consisted primarily of confirming last year’s pair was again occupying a particular nest site. For the small number of nests where one member of a pair did not return, there typically was a new recruit already occupying the vacancy by the time of my census–either a bird banded as a nestling on Cooper Island or an immigrant, indicated by its lack of any bands.

In the past, the high survivorship of breeding birds meant that some of the individuals I resighted each June were ones I had seen for over 20 years, and in many cases had known since I had weighed them daily as a nestling. The resightings of these individuals as adults provided an annual touchstone that was an important part of both my emotional and scientific connection to the colony.

My initial census of the colony this year was unlike any in the past. The loss of breeding birds over the winter was the highest on record. Nearly one-third of the 170 birds that bred in 2017 not returning to the colony in 2018.

As mentioned in an earlier post, many of the 50 pairs that had eggs this year (down from 85 in 2017 and 100 in 2016) consisted of widowed birds that both lost a mate over the winter. The decrease in breeding population was exacerbated by the paucity of previously nonbreeding birds present to recruit into the breeding population. Some established breeders widowed over the winter are the sole occupants of their nest sites. Even pairs that did survive the winter have shown much lower mate and site fidelity than I have observed in previous years.

The disturbingly high percentage of birds lost to overwinter mortality comes as a major surprise but a simple percentage fails to capture the full impact of what I experienced during this year’s census.

Many of the individual birds I have known for decades were among those absent from the colony. Most notable was Yellow-Gray- Green, a 21-year-old female banded as a chick in 1996 and breeding on Cooper since 2001. She was featured on the cover of last winter’s Audubon magazine. Another individual absent this year with an even longer history on the island is White-Gray-Blue, who fledged from Cooper in 1989 and bred on the island during 23 years of rapid environmental change including of decreases in sea ice, warming ocean temperatures, increased polar bear nest predation and major shifts in prey availability.

George’s “Cover Girl,” featured here on a December cover of Audubon Magazine, didn’t return to Cooper Island this year. Image Credit: Peter Mather for Audubon

While examining this year’s colony census at the level of the individual bird, versus a review of declining numbers is disheartening, it also provides some reasons for optimism–a rare feeling this field season.

My census found that a number of birds fledged from Cooper in recent years recruited into the breeding population this year, starting what I hope will be a long and productive career as breeders. These birds, and their young–the fledging chicks we hope they produce later this summer–provides one both with optimism and motivation to maintain the long-term study. As Hannah Waters pointed out in her excellent article in Audubon magazine, the guillemots are going to have to adapt and evolve for the colony to survive in a rapidly warming Arctic.

The hope that this year’s first-time breeders and their young will find a way to maintain the colony during the major changes occurring in the Arctic allows me to maintain a positive attitude as I continue to monitor this year’s breeding season.

Arctic Worries: Climate change impacts communities and wildlife in the Arctic

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.”

A MODIS image from July 11 (left) and July 16 (right); snow and ice are cyan color while clouds tend to be more grayish. Image Credit: NASA Worldview

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.

Sea ice since 1850. Image Credit: NOAA and University of Alaska Fairbanks International Arctic Research Center (UAF-IARC).

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?

We’ll just have to wait and see.

Fewer breeding pairs this season for Cooper Island guillemot colony

The Cooper Island Black Guillemot colony experiences a major decrease in breeding pairs as long-term decline accelerates.

As of July 6, egg laying ended at the Cooper Island colony and the number of breeding pairs is the lowest it has been in four decades. Only 50 guillemot pairs have laid eggs, down from 85 pairs last year, 100 pairs in 2016 and 200 pairs in the late 1980s.

Cooper Island breeding pairs over the years; it is important to note that the number of available sites has not decreased as the population has decreased, meaning some environmental factor has likely been decreasing the population. Image Credit: Jenny Woodman

A primary reason for the decline was increased overwinter mortality, with almost one third of the last year’s breeders failing to return to the colony. The long-term average for overwinter mortality is ten percent. Also contributing to the decline was a paucity of recruits to occupy the vacancies created by the mortality. Many of this year’s pairs are composed of two birds that lost mates over the winter. All recruitment that did occur were of birds that had fledged from Cooper Island. Immigrants used to constitute the majority of birds recruited into the breeding population.

A potential reason for the high mortality is the lack of sea ice in the area traditionally occupied by Cooper Island guillemots in winter. The unprecedented lack of sea ice over the Bering Sea shelf likely forced birds to occupy the ice edge in the Arctic Basin north of the Bering Strait, where prey resources may not be as abundant.

The 15 geolocators recently removed from returning birds will allow determination of the winter distribution.

The number of breeding pairs also declined due to the number of pairs maintaining nest sites but failing to lay eggs. Nonbreeding by experienced birds and established pairs has been extremely rare on Cooper Island but this year there are 20 such pairs. The presence of such birds, unable to initiate clutches after occupying a nest site, is an indication that overwinter or spring conditions caused both a decrease in the condition of returning birds as well as increased mortality.

Eggs will begin hatching in the third week of July and one has to hope fledging success will be high.