- Written by Clyde McMillan-Gamber Clyde McMillan-Gamber
Solitary sandpipers and Bonaparte’s gulls are unusual shorebirds in their respective families.
Each kind diverged from the nesting norms of its relatives to take advantage of resources in niches where their cousins don’t venture, thus eliminating competition for food and shelter with them.
Solitaries and Bonies are unrelated species that have characteristics in common because of their converging into the same summer habitat that shaped their bodies and behaviors.
In summer, these attractive species hunt invertebrates around ponds, lakes, and swamps when raising young in spruce/fir forests of Canada and Alaska, where few other kinds of sandpipers and no types of gulls nest.
Most other kinds of sandpipers rear offspring on the ground in the open Arctic tundra, and most gull species nest on the ground of treeless shorelines.
Every April and May, I am happy to see these interesting, migrating species stop to rest and feed here in southeastern Pennsylvania, as they do across much of the United States.
I enjoy their dainty, buoyant flight at local waterways and impoundments, where they fatten up on invertebrates. Solitaries get that food from mud under shallow water and Bonies from the air and on deeper water. Those invertebrates will sustain the next lap of their long trip north.
The lovely solitary sandpipers have a graceful, fluttering flight on deep wing strokes, which is an unusual sandpiper flight pattern. Other sandpipers have a powerful, speedy flight over open ground. And solitaries don’t migrate in groups, as other kinds of sandpipers do.
The handsome Bonaparte’s gulls are smaller and more petite than most gulls. And they have orange-red legs, black heads in summer, and an intriguing, uniquely bounding flight.
Perhaps because there is little open ground in woods, solitaries and Bonies hatch young in the safety of trees near bodies of water in Canadian and Alaskan forests, which is a departure from how their respective relatives hatch offspring.
Each female solitary lays four eggs in an abandoned cradle of an American robin, blue jay, or blackbird in a tree. The newly hatched chicks jump from the nest and scamper off to ingest invertebrates.
Unlike other North American gulls, each female Bonaparte’s gull builds a twig, grass, and moss nursery in a coniferous tree near a lake. There she lays three eggs. The babies stay in their nest until they can fly. Their parents feed them invertebrates and small fish.
Solitary sandpipers and Bonaparte’s gulls diverged from their relatives to get food and space, free of competition from their relatives. But these two unrelated species converged with each other because of the niche they share.
Yet they share in slightly different ways, which reduces competition for necessities between them.
Clyde McMillan-Gamber is a retired Lancaster County Parks naturalist.