The first known Cassin’s auklet chick of the year hatched at Southeast Farallon Island last week, and it looks like this:
These seabirds create burrows underground to nest in. This prevents predators like Western gulls on the Farallon Islands from easily preying on the young. The burrows are excavated by the birds themselves, with both parents using the sharp claws on their webbed feet to excavate the soil. On the Farallones, they also make good use of the man made nest boxes which allows biologists to monitor their breeding success.
The female Cassin’s auklet lays a single white egg. It hatches after about 40 days, and out pops a fuzzy black ball. The parents leave the burrow and come back at night to feed the chick by regurgitating food they picked up in the ocean. 40 to 50 days after hatching, the young Cassin’s auklet fledges (flies out of the nest) and into the ocean where it is able to swim and dive right away.
As adults, both the female and male Cassin’s auklet are small and stocky, with round heads and short necks. They are dark gray in color with lighter bellies, and have blue feet. Their bills are short and thick with a pale white spot at the base of the lower mandible. The white crescents above their eyes make them look like they have angry eyebrows.
They feed by “flying” through the water. Cassin’s auklets use their wings to propel themselves to depths of 120 feet below the ocean’s surface where they feed on shrimp, amphipods, copepods and some small fish and squid.
In 2014, thousands of Cassin’s auklet carcasses were found along the coasts of the western United States. Necropsies revealed little food in their stomachs, leading scientists to believe starvation was the main cause of death. This might have been related to the warm ocean waters at the time which could have reduced their food supply.