A Blog Post By Kerry Ross, BBI Biologist
There are few bird species that characterize the coastal Pacific Northwest as much as the Marbled Murrelet (Brachyramphus marmoratus). This small sea bird lives most of its life within 2 miles of land, in the Pacific Ocean where it forages for small fish, only coming ashore during the breeding season between April and August. It is during this breeding season when this small bird shows the unique nesting characteristics that sets it apart from all other birds of this region.
A basic plumaged (non-breeding) Marbled Murrelet well outside its normal range, San Diego, California (© Kerry Ross).
Almost all seabirds of the Pacific Northwest nest on cliffs or in offshore island burrows. Cormorants, fulmars, murres, and guillemots are all generally cliff nesters. When they nest on the mainland, their nests are usually on large cliff walls that are not accessible by mammalian predators. They also have another shared characteristic that is pretty common among seabirds – they lay white or light colored eggs with little or no pattern on the egg. The most notable exception are the gull species. While they also nest on offshore islands and inaccessible cliff faces, they also nest on the mainland in areas where mammalian predators can find their nests. This is why many gull eggs are camouflaged with mottled textures of various colors of cream, brown, and green.
The Marbled Murrelet, often called a Fog Lark by twentieth century loggers, was one of the last breeding birds in North America to have its nest documented or observed by biologists. They were hypothesized to nest on the mainland by early biologists long before their nests were ever found. The hypothesis was deduced by early female specimens that were collected during the breeding season and the eggs they contained were not white or ivory colored but mostly green with various shades of brown mottling covering them.
A Marbled Murrelet egg in redwood duff that has accumulated on a large branch of a coast redwood tree (Sequoia sempervirens).
Biologists reasoned that this murrelet must nest in the forest where an egg with these color patterns would most blend in. It was not until 1974, when an arborist had cut down a tree in the Santa Cruz California area, that the first Marbled Murrelet nest was discovered and documented by science. As it turns out, Marbled Murrelets do not build a nest at all! They use large “platforms” or branches of mature or old growth trees to nest on. These “platforms” must be at least 5 inches or greater in diameter. They lay a single egg directly on the branch of a large tree.
A recently fledged murrelet nest in a western hemlock in Humboldt County California (© Photo by J. Brett Lovelace, Used with permission from Humboldt State University Marbled Murrelet Project).
This murrelet chick is waiting motionless for its parents to return for their once a day food delivery from many miles away in the Pacific Ocean (© Photo by J. Brett Lovelace, Used with permission from Humboldt State University Marbled Murrelet Project).
I began my biology career conducting land-based Marbled Murrelet surveys in March of 1999, continuing and expanding on it over the next 14 years. It continues to be the most gratifying work I have ever done. After 6 years of working with many other species and groups of species, I once again had the opportunity to conduct murrelet surveys. The biologist who gave me my first job had a project that was far from his local area in Humboldt County, and he asked if Bloom Biological would be interested in helping out with the project during the breeding season between April and August of 2019. I assured him that I would be able to help out – I was elated that I was going to be doing murrelet surveys again!
Several of the tallest trees in the world and many Roosevelt elk reside in Prairie Creek State Park in Humboldt County California (© Kerry Ross).
Before a person can conduct murrelet surveys, they have to take a training class to become “certified” in conducting those surveys. I used to teach this training years ago, and I have to say I was a bit nervous to see if I had lost my skills of finding and recording marbled murrelets as they jet by at 50 mph plus in the early dawn hours. I was so excited to head north to Prairie Creek State Park in Humboldt County, CA to take part in the training. As it turned out, I had not lost my skills; I not only passed but my data was used to evaluate others in the training.
During the next few months I would do approximately 12 murrelet surveys in the Half Moon Bay and Santa Cruz areas. This is the southern edge of the Marbled Murrelets breeding range. In hopes of seeing or hearing marbled murrelets, I would rise from bed hours before dawn to hike into the survey station with a head lamp, backpack, and a recording device. Some of these hikes to a survey station were nearly an hour long in the pitch black of early morning. I had no idea what sort of view I would have, if any, until sunrise. Every day out there was a wonderful experience, but I was especially grateful for days when I got a view like the one in the photo below. It could have only been made better had I actually seen or heard any murrelets at this location.
A photo of the view of large coastal redwood trees from a Marbled Murrelet survey station near Half Moon Bay California (© Kerry Ross).
In July we did a murrelet survey in the Santa Cruz area on private property owned by a conservation group. This site had some residual old and late second-growth redwood trees that provided good breeding habitat for Marbled Murrelets. This site was extremely challenging to get to but once we arrived we had high hopes of detecting murrelets. We laid out a few survey stations for the following morning and went back to camp for the night. Rising at 04:30 we hiked 20 minutes into our stations and began our surveys. One of the stations was low in the drainage and one was higher up; it was at this higher station that got the first pre-dawn “keers” (vocalizations) from the early rising murrelets. A minute later at the lower station I began to hear them. Once the light began to break the darkness I was able to see the murrelets flying at speeds of 45-55 mph both up and down the drainage. They can be heard vocalizing on the sound file below.
After a short time of observing the birds in flight we both recorded a flight characteristic that is extremely important to a murrelet surveyor, called “occupied behavior”. This refers to the bird flying “at or below” the height of the tallest tree on the site. Occupied behavior can also be recorded if the bird does a 45° turn over the trees. This is suggestive of nesting behavior. If the site has a timber harvest plan then either of these two behaviors would constitute a freeze on the timber harvest plan and the site would likely be managed as-is without logging, indefinitely. There is no margin for error in these surveys. It could take another 200 years or more after logging before a stand of trees is appropriate habitat for breeding again. It is this fact that makes Marbled Murrelet surveys so important for the survival of the species. If a surveyor misses a single detection and the trees are logged, then that site will likely never again be appropriate habitat for murrelet breeding. That is why it only takes one observer, with one detection, lasting only one second and the habitat will likely never be manipulated by humans.
Much of the remaining coastal old growth redwood in California (< 5%) is still there because of State Parks, National Parks, and some in private hands. A lot of the old growth redwood in private hands is remaining because of Marbled Murrelet biologists working on timber harvest plans for logging companies having detected and recorded “Occupied Behavior” by murrelets during their surveys. These sites can sometimes be sold to conservation groups who manage them in a way that promotes forest growth and natural system dynamics.
The Marbled Murrelet is an iconic species to the Pacific Northwest as well as a biological wonder. Their lives on the battered nearshore Pacific Coast is remarkable in itself, but when you combine the breeding requirements with their wintering needs they are proven to be a truly exceptional species. If you ever make it to coastal northern California between late April and July (July being the best month) you should certainly visit Prairie Creek State Park and spend the early morning hours watching and listening to Marbled Murrelets as they dart in every direction, calling back and forth overhead and eventually disappearing into the 300 foot tall trees.
Keers! (As the Marbled Murrelet says)
—Kerry Ross
Note: BBI would like to extend our heartfelt condolences to everyone affected by the wildfires currently raging throughout California, including the lightning complex fires in Santa Cruz County. At this time, not much is known about the extent of the damage sustained in the murrelet territories within those redwood forests.