Common Murre Chicks Hatch for the First Time in 100 Years on the Channel Islands off Southern California
Last July, researchers from the U.S. Geological Survey (USGS) and the National Park Service (NPS) discovered that California Common Murre (Uria aalge californica) chicks had hatched on the Channel Islands for the first time since 1912.
The murre (pronounced "mrr," after the bird's characteristic vocalizations) is a football-size seabird of the auk family (Alcidae) that resembles certain black-and-white, tuxedo-clad penguins. Like penguins, murres use their wings to "fly" deep underwater, but unlike penguins, they also fly in the air. Historically, murres nested on Prince Island, a small islet off San Miguel Island within Channel Islands National Park. This colony disappeared nearly a century ago, likely as a result of human disturbance and egg harvesting.
In California, Common Murres are most abundant off central through northern California, with tens to hundreds of thousands of birds nesting at the Farallon Islands, off Trinidad Head, and at Castle Rock National Wildlife Refuge (see map). Smaller colonies occur farther south, on nearshore islets along the Big Sur coast and, now, on Prince Island.
"This is an exciting finding—certainly a historic one," said Josh Adams, a seabird ecologist with the USGS Western Ecological Research Center . "The murres appear to have reestablished their former southern range, perhaps benefitting from present ocean conditions."
The new colony is perched on 100-ft-high sea cliffs and was spotted by Adams, USGS biologist Jonathan Felis, and their Channel Islands National Park colleagues Laurie Harvey and David Mazurkeiwicz during research trips to this remote windswept island last summer.
Researchers Adams and Felis used boat-based telephoto images to document the murre colony and count its members on June 14 and 28 and July 12, 2011. During these three counts, total numbers of murres were consistent, between 125 and 129 individuals. Numbers of sitting murres holding sites and in "incubating posture" also were consistent in the three counts, at 89, 88, and 79. Photographs taken July 12 reveal a single broken eggshell amidst several adults holding fish in their mouths; one adult appears to be delivering a fish to a young nestling.
NPS biologist Harvey and murre biologist Mike Parker later observed several well-developed chicks on July 28, 2011.
For the first 2 weeks of their life, murre chicks are fed at the colony by their parents, which forage within about 50 km (30 mi) of their colonies and seek out abundant shoaling fishes, such as juvenile rockfishes, anchovies, and sardines. Using their wings to propel themselves underwater to depths of more than 150 m (490 ft), parents capture one fish at a time to feed the chicks. At about half the size of the parents and still unable to fly, 2-week-old murre chicks waddle off the cliff edges to the surf below. They join their fathers, which raise the chicks at sea until they are capable of diving and feeding on their own.
With this murre colony, Prince Island now hosts 13 nesting seabird species, making it one of the most important and biologically diverse nesting habitats on the west coast of North America.
Adams noted that the murres' recolonization of Prince Island "comes at an interesting time oceanographically, as conditions in the Santa Barbara Channel have been exceptionally productive during the past decade. Although many factors affect population redistribution and recovery, no doubt the murres at Prince Island are benefiting from relatively cool summertime waters, increased ocean productivity, and changes in forage-fish availability."
The California Common Murre is protected under the Migratory Bird Treaty Act, and the reestablished colony is afforded further protection by being situated in Channel Islands National Park, Channel Islands National Marine Sanctuary, and the recently designated Harris Point California Marine Protected Area.
Seabird biologists will continue to evaluate the future of the Common Murre colony at Prince Island. Partners in this monitoring effort include the Montrose Settlements Restoration Program and the California Institute for Environmental Studies.
More information on California seabird research is posted on the USGS Western Ecological Research Center's seabird-research Web site. More information about the Common Murre is available in a report published by the USGS in cooperation with the U.S. Fish and Wildlife Service that can be downloaded from http://www.archive.org/details/biologyconservat01geolrich.
in this issue:
Common Murre Chicks Hatch on Channel Islands