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Heermann's Gull

Larus heermanni ORDER: CHARADRIIFORMES FAMILY: LARIDAE

IUCN Conservation Status: Near Threatened

The strikingly marked Heermann's Gull is common along the West Coast of the United States. This gray-bodied, white-headed gull breeds in Mexico and then moves north along the Pacific Coast to southern British Columbia.

At a GlanceHelp

Measurements
Both Sexes
Length
18.1–20.9 in
46–53 cm
Wingspan
40.9–45.3 in
104–115 cm
Weight
13.1–22.7 oz
371–643 g
Other Names
  • Goéland de Heermann (French)
  • Gaviota de Heermann, Gaviota mexicana (Spanish)

Cool Facts

  • The Heermann's Gull, like many other gulls, frequently steals food from other birds. The Brown Pelican is a frequent victim. An adult Heermann's Gull is most likely to try to steal food from an adult pelican, and an immature gull is more likely to steal from an immature pelican.
  • The Heermann's Gull is the only North American gull that breeds south of the United States and comes north to spend the nonbreeding season. After breeding is over in July, the gull quickly comes north all the way to southern Canada. It heads back southward by December, and most breeders are at the breeding islands by March.
  • Perhaps as a result of the increasing populations in Mexico, several attempts have been made by Heermann's Gulls to breed in California. The first was on the island of Alcatraz. So far these attempts have been unsuccessful, but eventual successful nesting is expected.
  • The oldest recorded Heermann's Gull was a female, and at least 24 years old when she was caught and released in Oregon in 2009. She had been banded in Mexico in 1985.

Habitat


Shore-line

  • Nests on arid offshore islands.
  • Winters along coast and out to sea.
  • Rarely inland.

Food


Fish

Small fish, marine invertebrates, lizards, insects, refuse, and carrion.

Nesting

Nesting Facts
Clutch Size
1–3 eggs
Egg Description
Pale bluish gray to olive, with brown blotches.
Condition at Hatching
Semiprecocial with eyes open. Covered in down, grayish white mottled with dusky on back, pinkish buff on head and underparts.
Nest Description

Nest a shallow depression in the ground, or an open platform of sticks, dry grass, and weeds. Nests in colonies among boulders or nestled in grass.

Nest Placement

Ground

Behavior


Aerial Dive

Picks food from surface of water, plunges into water to pursue fish. Hovers and dips over waves. Steals food from marine mammals and other birds.

Conservation

status via IUCN

Near Threatened

There is little information on Heermann's Gull population trends. The North American Waterbird Conservation Plan estimates 350,000 breeding birds on the continent and lists it as a Species of Moderate Concern. These gulls rate a 16 out of 20 on the Continental Concern Score. Heermann's Gull is on the 2016 State of North America's Birds' Watch List, which includes bird species that are most at risk of extinction without significant conservation actions to reverse declines and reduce threats. The species is vulnerable to human disturbance because 90-95% of the total world population breeds on one island, Isla Raza. The island was made a wildlife sanctuary in 1964, and populations have increased since then. Heermann's Gull is listed as Near Threatened on the IUCN Red List.

Credits

Range Map Help

Heermann
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