TO KILL AN AUKLET
Two years after rhinoceros auklet birds began washing up on Northwest coasts, researchers are still trying to figure out what caused the mass die-offs.
Story by Kenzie Mahoskey | Photos by North Joffe-Nelson
On a calm summer day in 2016 near Port Townsend, Washington, Scott Pearson, a seabird researcher for the Washington Department of Fish and Wildlife, walked across the beach scouting out rhinoceros auklet birds. About 50 meters ahead, where a small break divided the waves, Pearson discovered a dead bird. Its small black body was peppered with sand, damp from the crashing waves. As Pearson picked up the bird, its head fell back, lifeless. This bird was not alone. Later that year, dozens more would be found, a warning sign of something sinister and unknown.
On the job, Pearson sees dead birds all the time. But during this event he was shocked by the scale.
Around 400 bird corpses washed ashore in the eastern part of the Strait of Juan de Fuca in Washington state, but Pearson estimated that there were many more deaths. In Victoria, British Columbia, about 100 dead rhinoceros auklets were also found between May 22 and July 27, 2016, in 29 different locations.
“It was unnerving when you see that many birds die.” Pearson said.
In a two month period, hundreds of rhinoceros auklets died suddenly. Researchers are scrambling to explain the phenomena, but the causes of the mass-mortality event are still unclear. A likely culprit may be starvation due to food shortages, but other experts believe the cause could be a mysterious bacterium which disappeared virtually overnight.
In the winter of 2014, a massive area of warm water, known as “the blob,” struck the Gulf of Alaska, increasing temperatures by as much as 3 degrees Celsius. The warmer water caused prey like plankton and fish to temporarily relocate, making them harder for predators to find. These changes affected the whole ecosystem.
Peter Hodum, a biology professor at the University of Puget Sound, believes there was something unusual happening with food availability. Data from Protection Island, which is in the Strait of Juan de Fuca, showed very small amounts of food in bill loads that the birds brought back to their chicks.
“It could be that the heat wave took out the food web and they all starved, or that they got the disease,” Pearson said.
Analysts are also determining if the deaths could have been caused by airborne diseases or other pollutants in the environment that may be affecting the food web, said Hillary Burgess, executive director of the Coastal Observation and Seabird Survey Team.
“Basically they’re doing a CSI investigation about why the bird is dying,” Burgess said.
Avian pathologists open up the birds and look for any abnormalities with the naked eye. In this case, they found dark red coloring in the lungs not normally seen in healthy birds, microbiologist Jeff Lorch said. Lorch then looks at the tissues and does culture work, growing bacteria from them to determine the kind of bacteria present.
According to Lorch, they have no idea where the bacteria came from. It’s unusual and doesn’t even have a name, so people refer to it as the bisgaard taxa 40, which is a slow growing bacterium, usually only found in gulls in Europe.
Based on data from Hodum and Pearson’s studies on chick numbers in 2016, after adult birds washed up on shore, their chicks starved in their burrows.
Hodum and Pearson visit Protection Island and search for rhinoceros auklet burrows hidden under the grass in order to monitor the health of the chicks. When they find one, they use a small camera on a pole, called a burrow probe, to see inside the nest.
“Usually we see a fluffy chick sitting there either looking at you, or sleeping,” Pearson said. “[After the die-off] we saw just lifeless balls of fluff.”
In 2017, no unusual adult mortalities were recorded and chick numbers went back to normal, Hodum said. Burrow occupancy was lower that year compared to previous years, and Hodum concluded that many adult birds died from the bacterial disease, resulting in a smaller population.
The disease was just something that came, hit the species extremely hard, then left, Pearson said.
“We just don’t know how it all ties together,” he said.
