Vermont Weekly Bird Notes: Sister Sparrows

Nelson’s Sharp-tailed Sparrow ©Ted Eubanks

What do you get when you plug a non-descript brown sparrow into an electrical outlet (do not try at home)? With brilliant yellowish-orange hues on their head and chest, Sharp-tailed Sparrows could win beauty contests in the sparrow family. How appropriate that this is the time of year they pass through Vermont, resembling the colors of the autumn sugar maples.

Once its own species, the sharp-tailed sparrow was “split” into two species in 1995 based on physical characteristics and DNA evidence. The Saltmarsh Sharp-tailed Sparrow is named for its preferred habitat, and breeds along the eastern coast as far south as Virginia. Their limited distribution makes their population particularly vulnerable to development pressures along the east coast. The Nelson’s Sharp-tailed Sparrow breeds further north into New Brunswick and Nova Scotia, in freshwater marshes in Central Canada to the Midwest, and around the James and Hudson Bays. The two species overlap in coastal northern New England.

Sightings of Sharp-tailed Sparrows are rare in Vermont, with only a few individuals reported each year. This week a Nelson’s was seen on two different dates at the Brattleboro Retreat Meadows. In recent years they have been spotted in marshes along Lake Champlain. Because they cling to the coast, Saltmarsh sparrows are extremely rare in Vermont (the last sighting was in 1986). Moreover, both species “skulk” around in grasses on the ground, and their secretive nature poses a challenge even for the most diligent and observant birder.

Eastern Sharp-tailed Sparrows spend almost their entire life cycle in saltwater marshes, making them potential candidates as “signals” of marsh health. Dr. Greg Shriver at the University of Deleware found that sharp-taileds are useful indicators of mercury contamination in Maine marshes. Interestingly, Saltmarsh sparrows have consistently higher mercury levels than Nelson’s sparrows within the same marsh. Shriver speculates that the larger saltmarsh sparrow may feed higher on the food chain where mercury accumulates.

This week’s bird reports were liberally spattered with other sparrows, including White-crowned, White-throated, Field, Savannah, Song, Fox and Lincoln’s sparrows. Migrants included flocks of Yellow-rumped warblers, Palm warblers, and Ruby-crowned Kinglets. An Orange-crowned Warbler was reported from Mt. Holly and from Whitney Creek. Pine siskins, Purple Finches, Juncos, and Evening Grosbeaks have been reported in flocks, often at feeders. A Red-bellied Woodpecker was seen at Whitney Creek and also at a feeder in Sunderland. Waterbirds continue to flow down Lake Champlain; Tuesday’s report included 123 Bonaparte’s Gulls, 93 Common Mergansers, 44 White-winged Scoters, and 50 Black Scoters. A Long-tailed Duck was seen from the Charlotte Town Beach, and Ross’s Geese have been sighted among the approximate 2000 Snow Geese at Dead Creek.

- Rosalind Renfrew