| Home: Special status species: Marbled murrelet: Natural history |
SPECIAL STATUS SPECIES: MARBLED MURRELET (Brachyramphus marmoratus)
NATURAL HISTORY |
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| General |
| Taxonomy: |
Order:
Charadriiformes; Family: Alcidae. There are 3 species
in the genus Brachyramphus: the Marbled
Murrelet, the long-billed murrelet (B. perdix)
and the Kittlitz’s murrelet (B. brevirostris).
The Marbled Murrelet and the long-billed murrelet
were classified as races of the same species until
1997.
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| Appearance: |
The Marbled Murrelet
is a small dove-sized alcid; adults are 23-24 cm (~9.5
in) long. The breeding and non-breeding plumages are
very different. The breeding plumage is "marbled"
in shades of brown, which is cryptic in forest nesting
habitat. The non-breeding plumage is black to dark
gray above and white below with white scapular patches
and collar. Juveniles appear similar to adults in
non-breeding plumage, but with a brownish-tan coloring
on the breast and flanks. The bill is long, slender,
and pointed. They have small, narrow, pointed wings
that are used for propulsion both in the air and under
water. |
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| Feeding Behavior |
| Overview: |
Like all alcids, the Marbled
Murrelet is a wing-propelled pursuit diver. Foraging
dives are usually less than 30 m below the surface
and last 15-60 seconds.3
Marbled Murrelets often forage in pairs, though single
birds and larger groupings are seen. Schooling fish
are eaten all year and invertebrates are eaten primarily
in the non-breeding season because they are not fed
to chicks.3 |
| Prey Items: |
Marbled Murrelets forage on small schooling
fish (anchovy, sand lance, juvenile rockfish, smelt,
herring, sanddabs), large pelagic crustaceans (euphausiids,
amphipods, mysids), and squid. They may occasionally feed
on freshwater prey (e.g., salmon fry). The diet of
Marbled Murrelets in the MBNMS has not been rigorously
studied. |
| Method of
Capture: |
Most often the birds
dive well below the surface and swallow fish underwater.
Sometimes a murrelet will drive a dense school of
fish to the surface and keep it there as long as possible
with shallow dives. |
|
| Reproduction |
| Overview: |
Only recently were the nesting
habits of the Marbled Murrelet determined: the first
nest found by ornithologists was in Asia in 1961 and
a North American nest was not found until 1974. Marbled
Murrelet pairs appear in nesting habitat in March
and April. The parents take turns incubating the egg,
changing places every morning at dawn. For about four
weeks, one incubates while the other one forages at
sea. Once the chick hatches, both parents feed it
until fledging. The chick leaves the nest during the
night and moves to the sea. This species is often
observed in pairs during the non-breeding season,
which suggests that the pair-bond is strong and lasts
over multiple breeding seasons.3 |
| Time to Maturity: |
Breeding probably begins at ages
2-5 years.3 |
| Longevity: |
~ 25 years.3
Peery and colleagues calculated a survivorship rate
of 0.882 for adults in central California.19 |
| Breeding
Season: |
Late March - early October3 |
| Frequency of
Breeding: |
Annual, though some females may not breed in years with low food availability3 |
| Clutch Size: |
One egg |
| # Clutches
per Season: |
One, but replacement
clutches may be laid after a failed attempt19 |
| Parental
Care: |
Both adults incubate
(27-30 days) the egg and feed the chick until fledging
(27-40 days post hatch). |
| Mating
System: |
Monogamous;
appear to establish long-term pair bonds |
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