Cover photo: © Tom Benson, 2014, Flickr Photo Album, some rights reserved.
- Marbled murrelets are seabirds that venture inland to build their nests high up in redwood trees.
- The health of coast redwood forests affects marbled murrelet populations, since murrelets need redwood forest habitats to breed.
- Despite considerable conservation of redwood forests, marbled murrelet numbers are still declining by 4 percent annually.
- Scientists have found that predation by Steller’s jays attracted to campgrounds by human food is affecting marbled murrelet numbers.
- Since murrelets are seabirds, the health of our oceans could also be impacting marbled murrelet populations.
The Mystery of the Marbled Murrelet
Our story begins with a mystery.
Marbled murrelets are robin-sized seabirds that are closely related to puffins and murres. As is the norm for other seabirds, scientists expected the marbled murrelet to nest in large colonies along the rocky coast. Yet no such breeding colonies of marbled murrelets were found, despite the habits of their close relatives. The nesting place of the marbled murrelet remained an unsolved mystery to ornithologists in North America for over a century.
This changed in 1974, when a worker performing maintenance at Big Basin State Park discovered a lone nest high up in a redwood tree. The nest contained a single chick, which strangely had webbed feet. He snapped a photo that was later identified by bird experts as a marbled murrelet youngster. The mystery of the marbled murrelet nesting place was solved.
Defying all expectations of a seabird, these clever nesters fly 20 miles inland to construct nests high up in the cover of redwood trees. With this discovery, the marbled murrelet became the most recent bird species to have its nest found in North America.
Logging and the Loss of Murrelets
The California Gold Rush of 1848 brought steep human population increases to the San Francisco Bay Area – and with these population increases also came a huge demand for lumber. Settlers turned to the redwood stands along California’s coast for their supply. The irresponsible logging stripped most of the old-growth redwood forest from our coastline. It is estimated that only 5% of old-growth coast redwood trees survived logging.
Coast redwoods are critical to breeding marbled murrelets. Thus, the declines of redwood forests were closely intertwined to declines in marbled murrelet populations. The low murrelet numbers recorded off our coasts resulted in their listing as threatened under the Endangered Species Act in 1992. In California, they are state-listed as endangered.
The fate of the murrelets, along with other calls for the reduction of logging in the northwest, led to the 1994 Northwest Forest Plan under President Clinton. The plan protected 9.7 million hectares of old-growth forest along the coast of California, Oregon, and Washington.
Despite the protected breeding habitats, scientists monitoring murrelet populations still found that their numbers were declining. The population around California, Oregon, and Washington is continuing to decline by as much as 4 percent per year.
Crumbs, Jays, and Predation
A study at Redwood National and State Parks discovered one potential cause of the murrelet declines: predation by other birds, namely Steller’s jays.
Steller’s jays are crested blue and black birds found along the west coast of North America and south into Mexico. They are corvids, belonging to the same family as crows, ravens, and other jays. In addition to their diets of plant matter and insects, they will eat the eggs and young of other bird species.
Steller’s jays are common at campgrounds, as their varied diet is supplemented by leftover food and crumbs from humans. These “crummy” areas attract jays and increase their density, thereby increasing the chances of Steller’s jays finding and predating the nests of marbled murrelets.
Public education programs are in place to decrease the amount of food left behind by humans. The initiative’s goal is to decrease the number of murrelet predators attracted to a given area. Signs are present in parks, warning people that food waste (even as small as a single crumb) has the potential to impact marbled murrelets.
Ocean Threats Still Loom
Scientists still don’t have all of the answers to what’s causing the murrelet population decline.
One factor affecting their numbers could be the availability of food off our coast. A study in Washington found that 80% of marbled murrelet nest attempts failed due to issues relating to low prey availability.
We do know that more frequent and intense El Niño events caused by climate change are negatively impacting fish populations. El Niño is a naturally-occurring phenomenon in which the number of upwellings of nutrient-rich cold water is reduced relative to “normal” years. Plankton, a main food source for fish, rely on the nutrients from the upwellings. With no plankton to eat, the fish populations (and the seabirds that depend on them) can be negatively impacted.
What does this mean for the marbled murrelet? Our efforts on land can be executed flawlessly, but the dual-lifestyle of this enigmatic seabird makes it so that their populations can still be harmed by threats to our oceans.
Stories such as these bring to light the importance of protecting as many diverse areas as possible. A holistic approach to conservation is necessary to save species that live such diverse lives.