Seabird Foraging under Study

Seagulls are the extreme example of a seabird that has learned to cohabitate with people. They thrive around us, are raucous like us and love fast food. They are loud, clever, extroverts with questionable dietary habits.

But what about other seabirds, the introverts of the bird world, the perhaps more timid species who may get spooked off a nest if a loud ship passes? How are these seabirds faring with fishing pressure, water pollution, continuing development and never-ending human bustle along much of the coast?

Dan Robinette is an ornithologist at PRBO Conservation Science who is asking these types of questions for several species of seabirds up and down the state. He recently presented some of what he’s learned about seabird foraging at the State of the California Central Coast Symposium in Monterey.

His work shows that seabirds are good at finding “retention zones” in the lees of coastal headlands, where small, young fish abound. He has also found that most of these fish-rich areas are not inside the Central Coast’s Marine Protected Areas.

In future work, he and colleagues hope to use seabird foraging activity as a way to map out where fish are recruiting and how fish recruitment patterns vary from year-to-year in response to coastal processes such as upwelling.

The scientists also continue to monitor seabirds for the Marine Protected Area (MPA) Baseline Data Collection projects, administered by California Sea Grant on behalf of the state of California.

Below are summaries of two ongoing projects in the South Coast and North Central Coast study regions.

Pigeon Guillemot

Pigeon Guillemots/

Use of Estuarine, Intertidal and Subtidal Habitats by Seabirds within the South Coast Study Region
R/MPA-28 Jun. 2011–Sep. 2014
Dan Robinette, PRBO Conservation Science, 805.735.7300,
Jaime Jahncke, PRBO Conservation Science, 707.781.2555, ext. 335,

In this project, ornithologists are evaluating whether the new MPAs are adequately protecting seabirds, specifically Pelagic Cormorants, Brandt’s Cormorants, Western Gulls, Black Oystercatchers, Pigeon Guillemots, California Least Terns and California Brown Pelicans, and if not, why. To do this, they are compiling and analyzing existing records of seabird populations prior to the establishment of the South Coast MPAs and conducting new bird surveys at key sites. Last year, scientists monitored seabird breeding colonies, rooting sites and foraging rates on Santa Cruz Island, in La Jolla (where there is also a Brandt’s Cormorant colony), at Cabrillo National Monument on Point Loma in San Diego and along the Palos Verdes peninsula in Los Angeles. The MPAs and special closures were established, in part, to protect roosting and breeding seabirds from passing ships, fishing lines and other human activities. As part of this project, scientists will be looking for evidence that the new regulations are reducing seabird behaviors, such as nest abandonment, that indicate disturbance. During the 2012 field surveys, researchers observed low numbers of chicks at all of the least tern colonies monitored. Fecal samples were collected to study whether their poor reproductive status might be due to diet. Findings from this project will be used to enhance and encourage science-based approaches to seabird conservation.

A Black Oystercatcher/Wikipedia Commons

Baseline Characterization of Newly Established Marine Protected Areas within North Central Coast Study Region—Seabird Colony and Foraging Studies
R/MPA-6 Mar. 2010–Dec. 2013
Dan Robinette, PRBO Conservation Science, 805.735.7300,
Gerry McChesney, USFWS, 510.792.0222, ext. 222,

In the first two years of this project, researchers refined protocols for monitoring six species of seabirds that are expected to benefit from the creation of North Central Coast MPAs—the Pigeon Guillemot, Pelagic Cormorant, Brandt’s Cormorant, Common Murre, Western Gull, and Black Oystercatcher. They have since documented each species’ population size, breeding success and foraging effort at several sites in Sonoma, Marin and San Mateo counties, and are investigating whether the region’s Special Closures are indeed protecting breeding colonies from human activities such as boating. A comprehensive tally of all the region’s nearshore breeding colonies is underway. The final deliverable of the project will be an overview of how seabirds are using coastal habitats inside and outside the MPAs, and the effectiveness of Special Closures in decreasing human-caused disturbance to breeding sites.

Written by Christina Johnson,

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2 thoughts on “Seabird Foraging under Study

  1. Pingback: Good South African sea bird news | Dear Kitty. Some blog

  2. Bird count and bird surveys can help in saving the endangered species. It is not only important to save them from getting extinct but also to maintain the ecological balance.

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