Creature Feature - Marbled Murrelet

June, 2015

 

 

 

Brachyramphus marmoratus

You’re probably aware that anadromous fish—salmon and steelhead—link our forest and ocean ecosystems in their life cycles, returning to their natal streams to spawn after maturing at sea. There’s another animal that links them on a daily basis, as a commuter, if you will:  the marbled murrelet.

This little bird, visually a bit smaller than a robin but weighing three times as much, is a member of the Alcidae, the family that also includes puffins, murres, guillemots, and auklets.  The world’s 24 alcids are sometimes called the “penguins of the north” since many of them look superficially similar to penguins and fill a similar ecological niche.

The marbled murrelet—or MAMU, as it’s known to bird nerds—ranges from central California to the tip of the Aleutian chain.  In some ways, it’s a classic alcid, spending most of its time at sea feeding on marine fish and invertebrates.  However, unlike most other alcids, which nest coastally on cliffs or in burrows, it nests high in trees in old-growth forests up to 25 miles or more inland.  (In the subarctic portion of its range, where there are no trees, it’s a ground nester).  This dependence on two disparate ecosystems makes the MAMU vulnerable to a broad set of conservation issues and makes preserving the species especially challenging.

The MAMU’s unusual nesting habits eluded ornithologists for 200 years, and it wasn’t until the 1970s that the first tree nest was documented.  We’ve learned a lot since then, but much of the species’ life history remains a mystery.  MAMUs lay a single egg on a large, mossy, horizontal limb and take turns incubating it in 24-hour shifts that turn over at dawn.  MAMUs are extremely vocal on their way to and from these exchanges, mostly uttering gull-like keer calls for which the bird has been nicknamed the Fog Lark and that enable MAMU researchers to detect them and determine whether forest stands are occupied.  After the chick hatches, the parents deliver up to eight seafood meals to it every day; as it grows, its droppings form a ring around it that helps keep it from falling off the branch.

At four to six weeks of age, the chick, perhaps motivated by hunger that its parents are no longer able to assuage, makes its maiden flight, solo, straight to the sea; growing up listening to those keer calls may help it orient in the proper direction.  Once there, it continues its development without parental assistance, eventually joining adults or other juveniles.  Most MAMU sightings at sea are of pairs, though the age and sex composition of these pairs is still unknown.

Not surprisingly, the MAMU has suffered tremendously from habitat loss caused by logging of the Pacific Northwest’s old-growth forests.  Habitat loss’s insidious partner, fragmentation, also threatens the species; higher edge to area ratios increase the risk of nest predation by jays and ravens.  (If you’ve visited the Redwood National and State Parks, you’ve seen signs that say, “Feed a Jay, Kill a Murrelet.”)   At sea, there’s always the risk of oil spills and other pollution; the Exxon Valdez spill alone killed an estimated 8,400 MAMUs.  And then there are the unpredictable effects of climate change on prey resources, with yet-to-be-determined consequences on the health of MAMU populations.

The MAMU was listed as Threatened under the US Endangered Species Act (ESA) in 1992 and is also listed as Threatened in British Columbia, Washington, and Oregon and Endangered in California.  The Northwest Forest Plan of 1994 has done perhaps more than any other legislation to protect the MAMU’s remaining nesting habitat while doing nothing to address the issues it faces at sea, where it spends most of its time.

The MAMU, in a sense, was fortunate in being able to piggyback on conservation policies driven by its more charismatic forest cohabitants, the Northern Spotted Owl and coho salmon.  But the logging industry has been waging an undercover war on the MAMU ever since.  Time and again, it has sued the government to remove the MAMU from the Endangered Species List; time and again it has lost.  In February, the US Court of Appeals rejected a suit by the American Forest Resource Council, which argued that the government had acted “arbitrarily and capriciously” in distinguishing US and Canadian MAMU populations, even though the ESA unambiguously recognizes populations defined
by political boundaries.

Let’s hope that this latest decision in favor of the MAMU, the fifth straight, is the final nail in the coffin (made of recycled wood, of course) of the timber industry’s attempts to undermine the ESA and return to its old, destructive ways.   Three cheers for keers!