Bird of the Month: Marbled Murrelet
By Hugh Jennings
Scientific Name: Brachyramphus marmoratus
Length 9.5-10 in
AOU Band code MAMU
The Marbled Murrelet (MAMU) is 9.5-10" long. The genus name Brachyramphus (brach-ih-RAM-fus) is from the Greek brachys meaning short, and nymphos, or beak for very short bill. The species name marmoratus (mar-more-AY-tus) is Latin for marbled and refers to mottled or irregular spots and streaks of summer plumage.
It is a small, chunky bird with a short neck and short bill. In summer the MAMU is dark brown above, mottled brown and white below. It may appear to have a darker cap and black tail. The similar Kittlitz’s Murrelet has finely mottled brown and white and has a shorter bill than the MAMU. In winter the MAMU has white lines on sides of black back. The black back extends below the eye, whereas the KIMU’s black cap is well above the eye.
The MAMU is a strange, mysterious little seabird. Although it is fairly common off the northern pacific coast, its nesting behavior was essentially unknown until the 1970s. It is now known to nest high in trees in old-growth forest several miles inland from the coast of the Pacific Northwest. They are generally found on the ocean on calm protected waters, such as Puget Sound, near coasts and in bays and inlets among islands. It does most of its foraging in fairly shallow water, but may forage in depths up to 100 feet. Even where common, it is usually seen in pairs or groups of pairs and not in large flocks. They will flush in front of approaching boats and fly away low with very rapid wingbeats.
Its diet is mainly small fish (sand lance, capelin, and herring) and crustaceans (euphausid shrimp, mysids, and amphipods. Very few nests have been found, so breeding behavior is poorly known. It is a solitary nester. Nests in the north may be on the ground on mountainsides among sparse or dense growth. In the south the nest may on a tree branch, up to 150 feet above ground and up to 15 miles inland. The nest is made mostly of moss. They have one egg which is light olive with dark marks. Incubation is by both sexes and lasts about 4 weeks. Both parents apparently feed the young, making feeding visits at night. The young leave the nest at about 27-28 days and probably fly directly to the sea or at least to a lake near the coast.
The MAMUs are generally resident near breeding areas, but some move south in winter with small numbers , rarely, invading the coast of southern California. They are highly vocal. The call is a twittering series of loud, high kree notes.