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Category Archive for 'Marbled Murrelet Tracking'

Radio Telemetry

By: Ethan Woodis, OMMP Field Crew Leader

Nesting season for the Marbled Murrelet is upon us! That means the Oregon Marbled Murrelet Project’s Coastal Telemetry crews are back on the coast. With the weather clearing up and the whales moving North, the tourist season on the Oregon Coast is in full force. For many people, seeing us on the coast with our radio telemetry gear pointed at the ocean can be a strange sight. For the record, we are not looking for, tracking or listening to whales, sharks or extraterrestrials. We are, also, not photographers, meteorologists or seismologists. And finally, our phone service is just as bad as everyone else’s on the coast and we are not using our antenna to boost the signal. What we are doing is using a radio telemetry receiver and a Yagi antenna to listen for Marbled Murrelets that have been tagged with a radio telemetry transmitter. If the bird with the attached transmitter is close enough to the receiver (within about three kilometers), the receiver will pick up the transmitted signal and start beeping. By listening for these beeps, recording where we are when we hear them and taking a bearing with a compass in the direction that the signal is being received, we are able to determine where the tagged murrelet is on the water. This will help us to understand the foraging habits of Marbled Murrelets on the Oregon Coast which will help us to better understand how we can help to protect this extremely unique species.

Photography by Ethan Woodis


That’s how and why we are using radio telemetry but what exactly is radio telemetry? Radio telemetry was the first real-time method of tracking individual animals over a long distance. In the field of wildlife research this has made it possible for researchers to track and study wildlife much more efficiently. The transmitters we use are VHF (Very High Frequency) tags. In the electromagnetic spectrum, VHF tags transmit between 30 and 300 MHz. More common uses of VHF are television, FM radio, armature two way land radio and Air Traffic Control to name a few. Some people may have seen radio collars on deer, wolves or other large animals. These are also VHF tags but they are much larger than what we put on murrelets. The larger the transmitter the longer the battery will live. That means in only a few months our transmitters will die. The tags fall of the bird during their fall molt and it can have a new one put on the following breeding season. Within the short lifespan of our tags we are able to learn where these birds forage and where they nest. As this is a very cryptic bird, this work would be impossible without the use of radio telemetry tags.

Photography by Jim Rivers


So, when you see us waiving our antennae toward the ocean seemingly oblivious to the Gray Whale calf foraging just off the rocks, you now know what we are searching for and how we are searching for it. Marbled Murrelets are an extreme difficult animal to study but with technology, lots of patience and even more coffee we are slowly unraveling the mysteries of these magnificent birds.

Photography by Holly Todaro

By: Stefanie Collar, OMMP Field Crew Leader

Field biology is often a puzzle, requiring months of careful preparation by the researchers to coincide with the natural behavior of wild animals and unpredictable quirks of the environment. Seabird projects can be especially complex- many seabirds spend most of their year at sea- small and secretive points of interest in the vast ocean- only coming to land for a few months out of the year. As a general rule, seabird colonies are usually loud, busy, crowded (and stinky!) places.  These colonies can be easy to identify, but not easy to access, because breeding seabirds gain an advantage over predators by nesting on remote offshore rocks, sea stacks and islands. Many such seabird colonies dot the Oregon coast, including Caspian Tern, cormorant and Common Murre colonies.

Photo Credit: Jon Felis

The exception to this rule can also be found (with some luck and much patience) here on the Pacific Coast. The Marbled Murrelet is a small seabird found along the coasts of Oregon, Washington and California, noticeable in the fall in its striking black and white winter plumage, but cryptic in the spring and summer in its mottled, russet breeding plumage. The Marbled Murrelet undergoes this unique molt before the breeding season each year because unlike other seabirds, it does not nest in raucous offshore colonies; the Marbled Murrelet nests in forests! And not just any forests, but in the towering, solitary conifers scattered throughout the coastal forests of the Pacific coast.

Though small (about the size of a dove) and seemingly not built for speed (they are often described as ‘potato-shaped’), Marbled Murrelets are agile and quick both in the air and in the water. Before the chick hatches, the murrelet pair trade responsibilities each morning at dawn- one individual staying at the nest for 24 hours to incubate the developing egg, and the other heading out to sea to feast on small fish.  They commute between their at-sea feeding grounds and their forest nests, which can be located up to 40 miles inland and in the canopies of trees hundreds of feet tall, at speeds reaching 60-miles an hour. Their forest-camouflage breeding plumage and speedy flights help Marbled Murrelets avoid the talons of avian predators, such as Bald eagles and Peregrine falcons, which see murrelets as a perfect snack. As the murrelet chick grows, the parents bring back meals of whole fish, each making several trips a day to ensure the chick grows fat and healthy as quickly as possible. If all goes well, after about 40 days, the Marbled Murrelet chick is ready to leave the nest on its own- making the first of many trips from forest to sea.

Photo Credit: Chelsea Hutton

Our job as researchers is to try and briefly intercept these birds during their day, in an attempt to learn more about them, but the unique life history of Marbled Murrelets means that this is not as simple as it sounds. Each piece of the murrelets life – the off-shore areas where it spends the night, the coastal zones where it forages, the forest where it makes its nest – requires a corresponding piece of field work. At night we use boats to explore the offshore areas where seabirds congregate, deploying small radio-tags on individual murrelets that allow us to track their movements; during the day we use radio telemetry to locate the tagged murrelets from cars and small planes; when a tagged murrelet is located inland, we hike through thickets of salmonberry and remote stands of old growth forest before dawn to watch and listen for the secret nests of murrelets. All these pieces come together to give us a clearer picture of not only what murrelets are doing in Oregon, but how they are doing, and how we can ensure they thrive for the coming generations.