Cassin's auklet

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Cassin's auklet

Near Threatened  (IUCN 3.1)[1]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Charadriiformes
Family: Alcidae
Genus: Ptychoramphus
Brandt, JF, 1837
Species:
P. aleuticus
Binomial name
Ptychoramphus aleuticus
(Pallas, 1811)

Cassin's auklet (Ptychoramphus aleuticus) is a small, chunky

North Pacific. It is the only species placed in the genus Ptychoramphus. It nests in small burrows and because of its presence on well studied islands in British Columbia and off California it is one of the better known auks. It is named for the American ornithologist John Cassin
.

Cassin's auklet is a small (25 cm, 200 g) nondescript auk. Its plumage is generally dark above and pale below, with a small white mark above the eye. Its bill is overall dark with a pale spot, and its feet are blue. Unlike many other auks, Cassin's auklet lacks dramatic breeding plumage, remaining the same over most of the year. At sea it is usually identified by its flight, which is described as looking like a flying tennis ball.

Cassin's auklet ranges from midway up the Baja California peninsula to Alaska's Aleutian Islands, off North America. It nests on offshore islands, with the main population stronghold being Triangle Island off Vancouver Island's Cape Scott, where the population is estimated to be around 55,0000 pairs. It is not known to be migratory. However, northern birds may move farther south during the winter.

Two subspecies are recognised:[2]

  • P. a. aleuticus – (
    Kurile Islands
    .
  • P. a. australis – van Rossem, 1939: southern Baja California.

An extinct relative or predecessor species, Ptychoramphus tenuis L. H. Miller et Bowman, 1958, is known from the Late Pliocene of the San Diego Formation in California.

Behaviour

Cassin's auklet nests in burrows on small islands, and in the southern area of its range may be found in the breeding colony year round. It either digs holes in the soil or uses natural cracks and crevices to nest in, also readily using man-made structures. Pairs will show a strong loyalty towards each other and to a nesting site for many years. Both the parents

sublingual pouch. The chick fledges
alone and makes its way to the sea. Cassin's auklet is unusual amongst seabirds in occasionally laying a second clutch after a successful first clutch (it is the only northern hemisphere seabird to do so).

Most individuals in a cohort begin breeding at age 3 (27%), and by 8 years >95% of a given cohort has recruited.[3] Mean age of recruitment is 3.6 years.[3] Minimum annual breeding propensity is 0.83, apparent local survival is 0.76, juvenile survival (ages 0 to 2) is 0.15.[3]

At sea Cassin's auklets feeds offshore, in clear often

pelagic water, often associating with bathymetric landmarks such as underwater canyons and upwellings. Numbers at sea may be grossly underestimated because the bird moves away from ships at a distance of more than a kilometer. Recently their distribution around Triangle Island has been determined by telemetry. It feeds by diving underwater beating its wings for propulsion, hunting down large zooplankton, especially krill
. It can dive to 30 m below the surface, and by some estimates 80 m.

Conservation

Cassin's auklet is listed as Near Threatened,

El Niño events). Cassin's auklet is protected under the Migratory Bird Treaty Act of 1918.[5] Annual variation in ocean climate synchronously affects multiple demographic parameters including survival, breeding propensity, breeding success, and recruitment, a situation conducive to rapid population declines due to climate change.[6]

2014 summer mass death in US

In the last few months of 2014, the carcasses of thousands of Cassin's auklets washed ashore from Northern California up to the north coast of Washington State.

Coastal Observation and Seabird Survey Team estimated a toll between 50,000 and 100,000 deaths that year. Scientists were uncertain about the cause of these deaths. While viruses, bacteria, and oil spills were ruled out the cause appeared to be starvation. Scientists found little evidence of food in the stomachs of the carcasses. Some scientists from the California's Farallon Institute believe these mass deaths could be related to the unusual North Pacific warmth which is pushing marine food chains[8][9] and could affect other species of zooplankton, krill and fish that normally develop in cold waters and the birds that consume them including Cassin's auklets. The event happened in the late summer when the auklet chicks began to fledge.[8]

References

  1. doi:10.2305/IUCN.UK.2020-3.RLTS.T22694903A180893939.en
    . Retrieved 11 November 2021.
  2. Rasmussen, Pamela, eds. (August 2022). "Noddies, gulls, terns, skimmers, skuas, auks"
    . IOC World Bird List Version 12.2. International Ornithologists' Union. Retrieved 10 November 2022.
  3. ^
    S2CID 85604692
    .
  4. doi:10.2305/iucn.uk.2016-3.rlts.t22694903a93475606.en
    .
  5. ^ CASSIN’S AUKLET Ptychoramphus aleuticus by the US Fish & Wildlife Service
  6. PMID 17302841
    .
  7. ^ Bird carcasses along Pacific shore baffle biologists, Los Angeles Times
  8. ^ a b "Mass Death of Seabirds in Western U.S. Is 'Unprecedented'". Archived from the original on January 26, 2015. Retrieved 25 January 2015.
  9. ^ "Unusual North Pacific warmth jostles marine food chain". Retrieved 25 January 2015.

Further reading

External links

Wikimedia Commons has media related to Ptychoramphus aleuticus.
Wikispecies has information related to Ptychoramphus aleuticus.
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