Bonaparte's Gull - Chroicocephalus philadelphia
Other Names:
Larus philadelphia
General Description
Sexes similar in all plumages. Breeding plumaged adult has entirely black head with narrow white eye-crescents, gray mantle, white tail, white underparts, black bill, and orange-red legs. Nonbreeding adult similar except head entirely white with characteristic dark ear spot behind eye, and gray hindneck.
Distribution
Montana Range
Observations in Montana: 119
Montana CountiesBeaverhead, Big Horn, Broadwater, Carbon, Cascade, Chouteau, Custer, Deer Lodge, Flathead, Gallatin, Garfield, Glacier, Granite, Hill, Lake, Lewis and Clark, Liberty, Lincoln, Madison, McCone, Meagher, Musselshell, Park, Phillips, Powell, Prairie, Ravalli, Roosevelt, Rosebud, Sanders, Sheridan, Stillwater, Teton, Valley, Wheatland, Yellowstone
Migration
Most of Montana is in the main migration path. Bozeman migration dates are May 4 to 15, with peaks on May 10. Fall records are mostly for November (Skaar 1969).
Habitat
Bonaparte's Gulls prefer larger lakes, but occur on smaller ponds as well (Skaar 1969).
Food Habits
Diet consists of small fish, euphausids, amphipods, and insects.
Reproductive Characteristics
Single brooded species with three eggs per brood. Incubation period twenty-four days.