Marbled Murrelets Use Both Tree and Ground Nests in mainland Southeast Alaska

(June 6, 2014, The Condor: Ornithological Applications)—A new study suggests that conservationists who want to preserve habitat for Marbled Murrelets should look both high and low in Alaska, where as many as 90% of the species breed. The study shows that Marbled Murrelets nest on cliffs and on the ground as much as they do in trees at one mainland location in the southeast part of the state. The research is the first of its kind to document the nesting sites and to determine the reproductive success of Marbled Murrelets in the remote terrain of southeast Alaska. Previous studies have found that Marbled Murrelets usually build their nests near the tops of towering, moss-covered trees from California to British Columbia, and mostly on the ground and on cliff ledges in the treeless landscape of western Alaska; but it was unknown to what extent the birds sought nesting habitat other than old-growth forest in southeast Alaska. Lead author Blake Barbaree and his co-authors confirmed that Marbled Murrelets nesting in southeast Alaska will use forests, rock cliffs, and sometimes the ground in subalpine areas or other high-elevation areas where snow and ice cover melts early in the year. They also discovered that nests within forests were more likely to have a chick survive long enough to begin its sometimes lengthy first flight to the sea, suggesting that forests provide better protection for nest sites.

The researchers followed radio-tagged Murrelets to 33 nests along a remote, mainland fjord in southeastern Alaska. The scientists found that many birds nested in trees, but about half of the birds nested on the ground on remote rocky slopes, up to 50 km from the coast and as many as 5 km from the nearest tree. Tree nests had higher success rates than cliff and ground nests, but the reasons behind nest failures were unknown. Overall, about 20 percent of the nests had a chick survive to at least 20 days after hatching. “Nesting success was lower than we expected and similar to studies in Washington and California,” said Barbaree, who conducted the research as a graduate student at Oregon State University. The authors suggest that additional research is needed to understand the factors that influence nesting success and the relative importance of these two nesting habitats in southeast Alaska.

The researchers used night lighting to capture Murrelets and then attached tiny radio transmitters to the birds. Barbaree followed the transmitter signals by plane, boat, and on foot. “The sheer ruggedness of the places the birds were going to nest and how far inland—I was in complete awe of what we were finding,” Barbaree said. Although the scientists could not reach most nests by foot, they used the transmitter signals to monitor the movements of the birds between their inland nests and at-sea feeding areas. Based on different behavior patterns known to be associated with incubation of eggs and rearing of young, the researchers were able to determine whether eggs hatched and then for how long parents visited the nests to feed chicks.

Marbled Murrelets are listed as endangered on the International Union for Conservation of Nature Red List. The populations in California, Oregon, Washington, and British Columbia have been on the U.S. Fish & Wildlife Service’s list of threatened species since 1992; the population in Alaska is not listed by the U.S. Fish & Wildlife Service.

“Nesting ecology of Marbled Murrelets at a remote mainland fjord in southeast Alaska” is online at http://www.aoucospubs.org/doi/full/10.1650/CONDOR-13-116.1.

Contact: Blake Barbaree, bbarbaree@pointblue.org

About the Journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. The journal began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society (www.cooper.org). The Condor: Ornithological Applications is one of the world’s foremost ornithological journals.

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