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| Murrelets in the News - and It’s All Bad In February 2007, two major scientific reports were released concerning the Marbled Murrelet. This robin-sized seabird nests in the canopy of coastal ancient forests from central California to Alaska, and is listed as a threatened species in the lower 48. Populations of murrelets in California, Oregon, and Washington have crashed in recent decades, in large part because of loss of nesting habitat due to logging. However, the species is far more numerous in British Columbia and Alaska, and this fact was used as the basis of a lawsuit by the timber industry to force the Marbled Murrelet off the Endangered Species list. In response to the lawsuit, the Bush administration ordered a review of the Marbled Murrelet’s status throughout its range. The results are now in, and, as was the case in a recent review of the population status of the Spotted Owl (also conducted due to timber industry pressure), the data show that the Marbled Murrelet is in even worse shape than we thought. The first comprehensive look at population surveys in Alaska and British Columbia found an overall decline of about 70 percent over the past 25 years, dropping the estimated population to 270,000 birds in Alaska and 54,000 to 92,000 birds in British Columbia. In other words, the "stronghold"of the species is not looking secure at all. The author of the review, federal seabird biologist John Piatt, stated that none of the known human-caused threats to Marbled Murrelets, including oil spills, gill nets, and loss of nesting habitat to logging, appeared adequate to explain the drastic and widespread declines, particularly in Alaska. It is possible that changes in ocean conditions, perhaps related to climate change or to overfishing, may be responsible. In the other study, researchers at U.C. Berkeley estimated rates of murrelet reproduction and survival by documenting the ratios of birds in different age groups using museum specimens collected between 1892 and 1922. They compared these results with values predicted from comparison with other bird species, and with contemporary rates obtained from murrelets captured at sea and from mark-recapture studies. Based upon the study, the researchers estimate that 100 years ago, there were nearly 30 juvenile Marbled Murrelets - those less than a year old - for every 100 adults in the central California population they studied between Half Moon Bay and Santa Cruz, a ratio that was nearly identical to that predicted from comparative analysis. Today, there are only three to four juveniles for every 100 adults. At the historic rate of reproduction, a marbled murrelet population would have experienced a stable to healthy growth rate of 2 percent per year. The authors note that murrelets only lay one egg each year, so the population, even when healthy, likely never grew very quickly. The modern-day reproduction rate indicates a population declining at a rate of 7 to 9 percent per year. This change in reproduction levels suggests limitations in nesting habitat and food availability, and increased predation on eggs and chicks by jays and ravens, according to the study’s authors. "Our results suggest the marbled murrelet will need all the protection it can get - both on land and at sea - to recover healthy rates of reproduction," said lead scientist Dr. Steve Beissinger. "Unfortunately, the U.S. Fish and Wildlife Service recently proposed to greatly reduce the area of old growth forest designated for protection as critical habitat for this bird and has not protected near-shore habitats at sea, where the murrelet spends most of its life." (Home) |
| Something to ponder: "The last word of ignorance is the man who says of an animal or plant: 'What good is it?' If the land mechanism as a whole is good, then every part is good, whether we understand it or not. If the biota, in the course of aeons, has built something we like, but do not understand, then who but a fool would discard seemingly useless parts? To keep every cog and wheel is the first precaution of intelligent tinkering." Aldo Leopold, The Sand County Almanac |
| Rogue Valley Audubon Society PO Box 8597 Medford, OR 97501 roguevalleyaudubon.org |
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