Updated February 9th, 2024
Beginning in early January 2024, Cassin’s Auklets (CAAU) began washing ashore in Oregon and Washington in unexpected numbers.
A Cassin’s Auklet, Ptychoramphus aleuticus, is a small (~200g, or 7oz) krill and larval fish-eating seabird that breeds along the West Coast of North America, from Baja to Alaska. Easy to recognize, Cassin’s have blue feet (when alive, or freshly beachcast!), dark back and wings, pale belly, and a pale spot on the lower bill right at the chin. Cassin’s nest in burrows dug into the ground, in colonies that reach hundreds of thousands of pairs.
So far, COASSTers living along the coastline of Northern California, Oregon, and Washington, have encountered, on average, 5 Cassin’s Auklets in each kilometer of beach searched (CAAU/km). The highest “encounter rate” (on a single beach) across all COASST regions was 200 CAAU/km, in the Northern Oregon region. Here’s what that looks like, broken down by region:
| Encounter Rate (CAAU/km) January 2024 | Encounter Rate (CAAU/km) Baseline* | Encounter Rate (CAAU/km) January 2015 | |
| Northern WA | 0.4 | 0.1 | 11.0 |
| Southern WA | 5.4 | 0.3 | 13.4 |
| Northern OR | 12.0 | 0.7 | 13.3 |
| Southern OR | 4.9 | 0.5 | 6.2 |
| Humboldt CA | 0.6 | 0.1 | 0.7 |
| Mendocino CA | 0.0 | 0.1 | 0.0 |
How does this year compare to our baseline?
In January over the last 25 years, the average encounter rate across COASST beaches in these regions has ranged from 0 CAAU/km to 13.4 CAAU/km, with the highest encounter rates recorded during the winter wreck of 2014-2015.
(If you weren’t following beached birds or mass mortality events in 2014-15, you can check out the COASST Science Update covering our synthesis of that event.)
Necropsies
While we aren’t sure why the Cassin’s Auklets were so numerous on our January surveys, we are gathering information. We’ve learned that four carcasses were collected by partners at ODFW in Oregon, and sent to the Wildlife Health Lab and the Oregon Veterinary Diagnostic Laboratory for analysis. So far, one specimen has tested negative for HPAI (avian influenza). Two carcasses were fresh enough for a necropsy, and the cause of death for those birds may be linked to starvation. Test results for cyanotoxin and BT40 (Mergibacter septicus sp) are pending.
Thank you for your work!
We don’t have to tell COASSTers – last month was a doozy! Thanks for all of your hard work out on your COASST beaches. Your reports this month (whether you counted 0 birds or 80!) have helped us track the start of this event.
While we hope it is coming to a close, there may be more Cassin’s Auklets on your February surveys. Remember to dress warmly, stay safe, and review your wreck protocols before you head out to the beach! (It’s quick and easy if you check out this blog post!)