Thayers Gull

Thayers Gull

Summary:

Profile Thayers Gull
[Authority] Brooks, 1915 | [group] Gulls and terns | [order] CHARADRIIFORMES | [family] Laridae | [latin] Larus thayeri | [UK] Thayers Gull | [FR]

[Authority] Brooks, 1915 | [group] Gulls and terns | [order] CHARADRIIFORMES | [family] Laridae | [latin] Larus thayeri | [UK] Thayers Gull | [FR] Goeland de Thayer | [DE] Thayermove | [ES] Gaviota esquimal | [NL] | copyright picture

Very similar in appearance to Herring Gull. Typical adult has pale todark brown (not pale yellow) eyes, little or no black
on underside of primaries, slightly darker mantle, darker pink legs, slighter bill. Overhead, the gray (not black) on the underside of the wing tips is distinctive. Some paler birds may have slate gray rather than black in
the outer primaries above.

Coastal waters, bays.
Winters mostly in coastal regions, especially around estuaries and protected bays, also well offshore at times. May regularly visit freshwater ponds and garbage dumps in coastal plain. Rare in winter farther inland around lakes, rivers. Nests on rocky coa
sts of northern islands.

Omnivorous.
Diet includes many small fish, also carrion, mollusks, crustaceans, berries. Around colonies of smaller seabirds, may take eggs or young. Also may feed on refuse around garbage dumps, docks, fishing boats.
Behavior: Forages in flight by dipping to surface of water to pick up items or by plunging to just below surface; also feeds while swimming or walking.


This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence 30% decline over ten years or three generations). The population size may be moderately small to large, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern. [conservation status from birdlife.org]


Breeding behavior not well known, but probably somewhat similar to that of Herring Gull. Probably does not breed until 4 years old. Nests in colonies, sometimes in association with other species of gulls or other birds.
Nest: Site is on ledge of rocky cliff close to ocean, usually facing fjord or sound on Arctic island. Nest (probably built by both sexes) is a low mound of plant material with a hollowed-out depression at the center.
Clutch 2, sometimes 3. Buff to olive or gray, with darker brown blotches. Incubation probably by both sexes; incubation period not known.
Young: Both parents probably feed young. Age of young at fledging and at independence not known.

Arctic Canada. Winters mainly on Pacific coast. Migration: Most birds from central Canadian Arctic move so
uthwest to Pacific coast. Rare farther east in winter. Young birds tend to move farther south than adults; most found in southern California and northwestern Mexico are first-winter immatures.

Specification

  1. Measurements
  2. spanwidth min.: 130 cm
  3. spanwidth max.: 140 cm
  4. size min.: 52 cm
  5. size max.: 60 cm
  6. Breeding
  7. incubation min.: 25 days
  8. incubation max.: 28 days
  9. fledging min.: 65 days
  10. fledging max.: 75 days
  11. broods 1
  12. eggs min.: 1
  13. eggs max.: 4
  14. Conservation Status
  15. Thayers Gull status Least Concern
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