Bonaparte’s Gull (Chroicocephalus philadelphia) is a small and elegant species of gull native to North America. It’s distinctive among gulls for its size, graceful behavior, and unique nesting habits. Here’s a comprehensive overview covering its identification, behavior, habitat, migration, and more:

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Identification

Size: One of the smallest gulls in North America.

Length: ~11.5–13.5 inches (29–34 cm)

Wingspan: ~30–33 inches (76–84 cm)

Weight: ~180–225 grams

Plumage: Breeding plumage: Striking black hood, white eye crescents, pale gray back, white underparts, and black-tipped wings. Non-breeding plumage: White head with a dark ear spot; the black hood is lost.

Bill: Thin, black, and relatively short.

Legs: Reddish or orange during the breeding season.

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Behavior

Flight: Agile and tern-like, often flitting over water with quick wingbeats.

Feeding: Catches insects mid-air or picks them off the surface of the water. Also eats small fish, crustaceans, and other aquatic invertebrates. Forages singly or in small flocks; occasionally associates with larger gulls or terns.

Vocalization: High-pitched and nasal calls, less raucous than larger gulls.

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Habitat

Breeding: Prefers boreal forests near freshwater lakes, ponds, or bogs—especially in Canada and Alaska.

Unique among gulls: Nests in trees, usually conifers, often on a horizontal branch over water.

Non-breeding / Wintering: Found along both Atlantic and Pacific coasts, Great Lakes, and inland reservoirs and rivers. Often seen in estuaries, bays, lakeshores, and even urban water bodies.

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Migration

Highly migratory: Travels between boreal breeding grounds and wintering areas across the southern U.S. and Mexico.

Timing: Spring migration: March to May Fall migration: August to November

Routes: Migrates through interior North America using major river systems and lake chains.

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Breeding

Season: Late May to July.

Nests: Built in trees (rare for gulls), often in colonies; made of twigs, moss, and vegetation. Clutch: Typically 2–4 eggs.

Incubation: ~24 days by both parents.

Chick care: Parents feed chicks for several weeks until they fledge.

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Range

Breeding range: Northern Canada, southern Alaska.

Wintering range: Coastal U.S. (especially the Gulf Coast), Baja California, and parts of Central America.

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Conservation Status

IUCN Red List: Least Concern

Population trend: Generally stable, although local threats like habitat loss or pollution may impact some areas.

Protection: Covered under the Migratory Bird Treaty Act in the U.S.

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Fun Facts

Named after Charles Lucien Bonaparte, a French ornithologist and nephew of Napoleon Bonaparte. Rare among gulls for its arboreal nesting behavior. During migration, it may appear inland in large numbers, especially after storms.