French scientists have come out with a study offering a potential explanation for the spectacular winter die-offs seen in alcid species all over the world. Known as “wrecks,” these die-offs involve hundreds or even thousands of alcids (like Dovekies, puffins, and murres). Volunteers in our sister program, COASST, surveying beaches in the Pacific Northwest and Alaska see these wrecks among Common Murres almost every winter. Here on the east coast, Dovekie seem to be the most common victims turning up on our shores. One report from New York City in the 1930s reported Dovekies literally raining down in the streets after a storm. So certainly these phenomena are not new, but up to now, explanations for these events had been mainly speculative.
The new study out of Europe appears in the Journal of Experimental Biology and focuses on two species: Little Auks and Brunnich’s Guillemots. One of the reasons these die-offs have been so hard to study is the inaccessibility of seabirds during the winter months. Unlike during the breeding season when the birds congregate at nesting islands, in winter the birds are widely scattered and foraging in the open ocean. To combat this substantial challenge, the scientists utilized a computational model to estimate the metabolic demands placed on the birds by cold temperatures, severe storms, and unpredictable prey distributions. The results were startling: the 150g Little Auk would need to consume a stunning 289g of zooplankton each day to survive, and the 1000g Brunnich’s Guillemot would need to wolf down over half its body weight in small fish and crustaceans.
The scientists suggest that many of the birds are simply unable to find that massive amount of prey each day and succumb to cold temperatures and harsh weather. This hypothesis is certainly consistent with necropsy findings from alcids found dead on the beach; most are emaciated but show no other signs of illness or injury, suggesting that the birds simply starved to death.
Though winter wrecks are not new, this study begs the question: what will happen to alcid species as their prey base declines? Overfishing and climate change conspire to reduce the food available to all seabird species, and for these alcids, already on a knife’s edge of survival in the unforgiving Atlantic in winter, this could prove catastrophic. All the more reason for Seanetters to be out there watching the shores so we can detect shifts in mortality among these diminutive seafarers. So keep that in mind when these warm summer days fade and with it your resolve to survey. The alcids need you Seanetters!