Aleutian Tern

Onychoprion aleuticus

Order

CHARADRIIFORMES

Family

Gulls, Terns, Skimmers (Laridae)

Code 4

ALTE

Code 6

ONYALE

ITIS

Egg Color:

Olive to buff with dark brown markings



Number of Eggs:

1 - 3



Incubation Days:

22 - 23



Egg Incubator:

Both sexes



Nest Location:

On ground.



Nest Material:

Lined with plant material.



Migration:

Migratory



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General

Aleutian Tern: A medium-sized tern with white forehead, black cap, eyeline, bill, and legs, and gray underparts and upperparts contrasting with pure white rump and tail. Undertail coverts, cheeks, and area immediately below cap are also white. Wing projects slightly beyond tip of tail at rest. In flight, underwing has dark subterminal bar on secondaries, pale area on inner primaries, and dark-tipped outer primaries; upperwing shows bold white leading edge and broad dusky lines on at least 5 to 6 outer primaries when spread. Juvenile is buff and brown on top and flanks, with pale gray underparts.

Range and Habitat

Aleutian Tern: This bird breeds in coastal areas of southern and western Alaska, along coast of Chukchi Sea, on Seward Peninsula, along Alaska Peninsula, in widely scattered locations in Aleutian Islands, in Kodiak Archipelago, on Kenai Peninsula and Copper River delta, and along Gulf of Alaska. Breeding colonies found on vegetated islands, dwarf-shrub tundra, grass and sedge meadows.

Breeding and Nesting

Aleutian Tern: One to three olive to buff eggs with dark brown markings are laid in a depression on the ground, near water. Nest is lined with plant matter, including moss and matted grasses. Incubation ranges from 22 to 23 days and is carried out by both sexes. Both parents feed the young.

Foraging and Feeding

Aleutian Tern: Usually forages in shallow water, including tidal rips, along rivers, and over inshore marine waters. Occasionally adults and fledglings catch insects by hawking over freshwater ponds and marshes. Searches for food from moderate heights, by swooping down to pick prey items from the surface; by hovering and diving to shallow depths; and by sitting on the surface and dipping. Eats primarily fish and zooplankton.

Vocalization

Aleutian Tern: Call is a carrying staccato "chif-chif-chu-ak", which is more shorebird-like than ternlike. Also gives a short, sharp "chit." Calls from the air and on the ground at colonies. Generally silent while incubating.

Similar Species

Aleutian Tern: In Alaska, it might be confused with similarly-sized Arctic and Common Terns. The Aleutian Tern has a distinctive white forehead and a dark bar on the secondaries while Arctic Tern Breeding Adult has a black forehead and crown which extend onto nape.

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UnderpartsX

Belly, undertail coverts, chest, flanks, and foreneck.

Undertail covertsX
Small feathers that cover the areas where the retrices (tail feathers) attach to the rump.
UpperpartsX
Back, rump, hindneck, wings, and crown.
CapX
The area on top of the head of the bird.
Inner primariesX
The inner primaries are a group of feathers closest to the body on the wing of the bird. They are generally covered partially by the secondaries.
Outer primariesX
The outer primaries are the primary feathers on the wing farthest from the body. They often appear to be the longest feathers on the wing.
PrimariesX
The primaries are the flight feathers specialized for flight. They are attached to the "hand" equivalent part of the wing.
RumpX
The area between the uppertail coverts and the back of the bird.
SecondariesX
Flight feathers that are attached to the wing in the area similar to the human forearm and between the body and the primaries.
Parts of a Standing bird X
Head Feathers and Markings X
Parts of a Flying bird X