The Bonaparte’s Gull is a beautiful little gull that graces the lakes and gulf shores of Texas during winter. The Bonaparte’s is larger than only the Little and the Sabine’s Gull.
The Bonaparte’s is compared to the Ring-billed Gull below.
Adult Bonaparte’s are dapper even in non-breeding plumage which is all we see in Texas. They have a thin, black bill and pink legs. They usually retain a bit of the black-cap in basic plumage, especially a smudgy dot behind the eye. Though dainty, the Bonaparte’s is slightly rounded, with a tall head and graceful neck.
Bonaparte’s are regularly seen over inland lakes of Texas in winter, where the white leading-edge and black trailing-edge of the adults’ wings in flight can be spotted from a distance.
Bonaparte’s are buoyant and adept fliers and often pick small prey items off the surface or near-surface when feeding. This behavior can help in identification even at a distance. A sub-adult is shown in near-surface feeding in the video below.
Juvenile and Sub-adult Bonaparte’s
As mentioned above, by the time they reach Texas, Bonaparte’s have generally molted away from strictly juvenile plumage into sub-adult plumage. Therefore, I don’t have any photos of juvenile Bonaparte’s, but Cornell’s Macaulay Library does!
Sub-adult Bonaparte’s are another of the “M” birds which sport a roughly “M-shaped” black pattern on the back and wings. The “M” of the Bonaparte’s is more diffuse, and therefore less distinct than those of some other small gulls. A sub-adult gull in Texas that shows any sort of an “M” pattern on the back and wings is most likely a Bonaparte’s, however, the other “M” birds should be considered (Little, Sabines and Black-headed Gulls and the Black-legged Kittiwake).
When perched, sub-adult Bonaparte’s show adult colored mantle and scapulars and varying degrees of wear and feather-growth on the wing coverts and wings.
Odd Bonaparte’s
There’s always an oddball gull out there!! The apparently large, flat head, long bill, long wings, and bulging eye of this Bonaparte’s (photographed at Surfside Beach, Texas on 1/26/23) had me initially wondering if I had an out-of-range gull, such as a Black-headed Gull. However, once I sought expert advice it was (eventually) determined that the feathers of the head were slicked-down, perhaps due to moisture and this made the bill, head and eye look quite prominent. The pink legs, seen in one photo, are also characteristic of Bonaparte’s and not Black-headed. The odd Bonaparte’s is compared with a “normal-looking” Bonaparte’s photographed at the same time in the two composite photos below.
