Bonaparte's Gull

Chroicocephalus philadelphia




Gulls, Terns, Skimmers (Laridae)

Code 4


Code 6



Egg Color:

Olive to buff with brown blotches.

Number of Eggs:

1 - 4

Incubation Days:


Egg Incubator:

Both sexes

Nest Location:

In tree.

Nest Material:

Sticks and twigs and lined with grasses and moss.





Bonaparte's Gull: Medium gull with black head and bill, gray back, white eye crescents; white underparts; tail is white, tip is black; white outer primaries with black trailing edges visible in flight. Legs red-orange; black bill. Sexes are similar. Winter adult lacks black hood; white with dark spot behind eye; legs are pink. Juvenile is resembles winter adult but has brown-washed back, nape and crown and black-tipped tail. First-winter bird is very similar but has a darker diagonal bar across the upperwing coverts.

Range and Habitat

Bonaparte's Gull: Breeds across subarctic North America from western Alaska to the Hudson Bay. Spends winters along Atlantic coast from Virginia, along the Gulf Coast inland to southern Missouri, and south into northern Mexico, and along the Pacific coast from Washington south to central Mexico. Preferred habitats include large lakes, rivers, and marshlands.

Breeding and Nesting

Bonaparte's Gull: Both sexes build a cup-shaped nest made out of twigs, branches and tree bark and lined with grasses, mosses and lichens. Two to four brown blotched olive to buff eggs are laid in the nest. It is built near or over water. They typically build nests in a tree rather than on the ground. Both parents incubate the eggs for 24 days.

Foraging and Feeding

Bonaparte's Gull: These gulls feed mostly on insects picked off from the water surface, or from rotting vegetation along shorelines during breeding season. Their diet shifts to small fish, crustaceans, marine worms and other invertebrates in winter. They forage by picking food from the water surface while swimming or flying with dangling feet; they also make shallow plunge dives.


Bonaparte's Gull: Utters shrieking whistles and a call of "cheer."

Similar Species

Bonaparte's Gull: Black-headed Gull has dark red bill and dark primary undersides.

The crown is the top part of the birds head.
Also called the hindneck or collar, it is the back of the neck where the head joins the body.
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.
The primaries are the flight feathers specialized for flight. They are attached to the "hand" equivalent part of the wing.
Parts of a Standing bird X
Head Feathers and Markings X
Parts of a Flying bird X