ID-Tip Tuesday: Sorting through gulls, Little by Little

Photos and text by Tom Johnson

The period from mid-March through April marks the peak of spring migration of Bonaparte’s Gulls through eastern North America, both along the coast and over inland rivers and reservoirs. Little Gulls frequently winter and migrate with Bonaparte’s Gulls in North America, so be sure to scan through any flocks of Bonaparte’s with an open mind.

adult Little Gull. Villas, Cape May Co., New Jersey. March 2014.

adult Little Gull. Villas, Cape May Co., New Jersey. March 2014.

adult Little Gull. offshore Atlantic County, New Jersey. November 2013

adult Little Gull. offshore Atlantic County, New Jersey. November 2013

 

When I search through flocks of common species, I like to have a good “search image” in place for the rarities that I am most likely to encounter. When looking through flocks of Bonaparte’s Gulls, the list of search image necessities includes both Little Gull and Black-headed Gull. While it can be difficult to develop a search image without prior experience with a species, studying photos and field guide plates can be very effective in helping to prepare for future rarity sightings.

adult Little Gull with Bonaparte's Gulls. Villas, Cape May County, New Jersey. March 2014

adult Little Gull with Bonaparte’s Gulls. Villas, Cape May County, New Jersey. March 2014

Little Gulls are smaller than Bonaparte’s Gulls, and they have blunt, slightly rounded wingtips. Adults have largely blackish under-wings and a thin white trailing edge to the upper-wing; they lack the patch of white outer primaries that makes the upper-wing of a Bonaparte’s Gull so distinctive. At rest, Little Gulls show pale gray and white folded primary tips, while Bonaparte’s Gulls show black here. In winter, adult Littles have pale heads marked with a dark spot behind each eye and a dark cap; by late spring, they molt in a fully black hood, which they keep through the summer.

I usually first notice adult Little Gulls when I see a flash of a black under-wing while scanning through a flock of Bonaparte’s Gulls. Then I can focus in on that bird to check its overall size, wing shape, head pattern, and upper-wing markings. Occasionally, especially in the Great Lakes region, surprising concentrations of Little Gulls will crop up in the vast flocks of Bonaparte’s Gulls, and you can sometimes even compare two or three age classes of Little Gull within a flock.

adult Little Gull with Bonaparte's Gulls. Churchill, Manitoba. June 2009.

adult Little Gull with Bonaparte’s Gulls. Churchill, Manitoba. June 2009.

14 Little Gulls with large flock of Bonaparte's Gulls. Presque Isle, Lake Erie, Pennsylvania. March 2013.

14 Little Gulls with large flock of Bonaparte’s Gulls. Presque Isle, Lake Erie, Pennsylvania. March 2013.

A few reliable areas to check for migrating Little Gulls include the following:

Ontario – north shore of Lake Erie, especially near Long Point; north shore of Lake Ontario, such as Oshawa Second Marsh

Ontario/ New York – Niagara River corridor

Pennsylvania – Presque Isle State Park near Erie; Susquehanna River south of Marysville

Maryland – Susquehanna River from either Lapidum or Port Deposit

New Jersey – South Amboy; Sandy Hook; Delaware Bay side of Cape May