Los Farallones

Dispatches from Point Blue’s field station on the Farallon Islands National Wildlife Refuge

Netting For Fish

By Miles Scheuering

Lying in wait for a rhinoceros auklet to fly into the mist net. Photo by Mike Johns.


It is the peak of the chick-rearing period for rhinoceros auklets on Southeast Farallon Island, which means every night the adults return to their burrows with bill-loads of fish for their chicks. As part of a long-term monitoring study of their diet, we use mist nets to capture adults and collect the fish they carry. Once the netting is complete, we identify the species and measure the size of each prey item to determine energy content. Types of prey generally include juvenile rockfish, anchovies, sablefish, and squid; and this year the chick diet has been almost exclusively anchovy. They have specialized hooks on the backs of their tongues that allow them to carry as many as eight fish at a time. That’s a lot of fish! By handling the birds we are also able to band and measure adults to improve our demographic data, along with deploying geolocators (leg-mounted archival tags used to estimate geographic positions of birds over year-long deployments).

Waiting for provisioning rhinoceros auklets at Stonewall Catacombs netting site. From left to right: Miles Scheuering, Haley Land-Miller, Grace Kumaishi, and Emma Railey. Photo by Mike Johns.


We set the net up at sunset and lie in wait on either side for birds to fly in. As soon as a bird makes contact, people run over and begin extracting the bird, while others search for fish that have fallen on the ground. They are feisty birds and are not afraid to nibble on your hand while you are trying to extract them. These diet samples are valuable in determining the foraging success of provisioning parents, as well as a tool for monitoring fish abundance within the Gulf of the Farallones where these birds feed.

Extracting a rhinoceros auklet from the net. From left to right: Haley Land-Miller, Maya Sterett, Theresa Rizza, and Eva Hasegawa. Photo by Mike Johns.