Species and Plant Community
Accounts for Identified Wildlife

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CASSIN'S AUKLET (Ptychoramphus aleuticus)

Status

The Cassin's auklet is BLUE-listed, primarily due to threats stemming from introduced predators such as rats and raccoons. Oil spills and drift nets are also threats. British Columbia supports approximately 80% of the known breeding population of this species, the majority of which nest on Triangle Island.

Ecology

The Cassin's auklet is a small seabird that feeds along most of the outer coast in offshore waters. It comes to land only to breed, from late spring through summer. The Cassin's auklet is a burrow-nester, occupying sites with grassy or low shrub cover. Most colonies in the Queen Charlotte Islands are located on the perimeter of islands forested with Sitka spruce, western redcedar, and western hemlock. Although similar in size to the ancient murrelet (S. antiquus), and often occupying the same islands, the Cassin's auklet produces only one egg per year, and chicks are not precocious but are fed in the burrow for several weeks before departing with their parents. They do not return to the colony until they are ready to attempt breeding, usually at around age three.

Distribution

Ecoprovince: Ecosections

Biogeoclimatic units

Breeding range

The Cassin's auklet breeds on islands off the west coast of Vancouver Island and the central-northern mainland coast, and on islands of the Queen Charlotte archipelago. Approximately 70 nesting areas are known in B.C. and most have some form of protected status.

Nonbreeding range

The Cassin's auklet lives at sea outside the breeding season.

Habitat requirements

Broad ecosystem units


Structural stage

2: herb
3a: low shrub
7: old forest

Critical habitats and habitat features

All Cassin's auklet nesting colonies are on islands. Nesting burrows are tunneled into soft soil on slopes and sometimes under the base of trees, stumps or fallen logs. In some areas, burrows are found in rocky grasslands or shrubby areas.

Like most seabirds, the Cassin's auklet is highly vulnerable to introduced predators. Colonies are also sensitive to disturbance by humans, even by foot traffic, particularly when burrows are dense and shallow.

Selected references

Rodway, M.S. 1991. Status and conservation of breeding seabirds in British Columbia.
Delta, B.C. ICBP Tech. Publ. No. 11.


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