‘Canary in the Mine’ for the Salt Marsh

— this article by Deidre Robinson, Wenley Ferguson and Steve Reinert first appeared in WildforaRI, Spring 2091

If you’ve never experienced the sunrise over a salt marsh, inhaling the distinctive fragrance of hydrogen sulfide given off by decomposing smooth cordgrass (Spartina alterniflora) and hearing the dawn chorus of marsh birds, you might want to explore one sooner rather than later. The marshes are disappearing at an alarming rate.

The saltmarsh sparrow is an obligate salt marsh specialist, living only in the marshes along the east coast of the United States. Rhode Island provides critical habitat for several small pockets of this threatened species, whose population has plummeted by 75 percent since the 1990s. With accelerating sea level rises, tidal marsh losses of 0.5 to 1.5 percent annually are predicted, likely dooming this bird to extinction by 2040.

We first spotted this sparrow at Jacob’s Point Salt Marsh in Warren on a steamy July day in 2016 while conducting a survey of breeding birds for the Rhode Island Bird Atlas. She was stealthily returning to her nest to incubate four small eggs. Rather than fly directly to the nest and possibly reveal its location to a predator, she lands in a patch of salt meadow several meters from the nest, then zigzags through the grasses running much like a mouse, a strategy that has worked well for it for millennia.

Locating an active nest of this threatened species is always cause for celebration, but we had discovered a bird that had been previously banded–an extraordinary bonus. Contacting the Bird Banding Laboratory at the US Geological Survey in Laurel, MD, we learned that she had been banded in Florida in the fall of 2015. She had likely hatched at Jacob’s Point that spring, over-wintered in Florida, and returned to breed in Rhode Island the following summer. Weighing the equivalent of just three nickels, she made the arduous round-trip of 1440 miles and now holds the record for the longest migration distance for her species.

This discovery launched the Saltmarsh Sparrow Research Initiative (SSRI), a local citizen-science project to document the breeding ecology of this vulnerable bird. With permission from the Warren Land Conservation Trust (WLCT) to access its marsh property, we began a five-year comprehensive study of the sparrow, including documenting changes in the marsh flora and measuring the elevation of nests, which are increasingly vulnerable to flooding. (Read much more about our research on www.SALSri.org.)

During the first two years of our study, we banded 88 adult saltmarsh sparrows and found 101 nestlings. We also documented the elevation and surrounding vegetation for each of the 56 nests we located. We found that nests are increasingly subject to flooding, a finding consistent with other studies that report rising tides as the major threat to this species, which cannot survive in any other habitat.

This obligate species thrives in a healthy salt meadow community of Spartina for nesting, intermixed with saltgrass (Distichlis spicata), saltmarsh rush (Juncus gerardii) and maritime marsh- elder (Iva frutescens). Its breeding strategy is one of promiscuity, with males often perching on the marsh-elder to scan for females. (Typically, nests contain eggs fertilized by two to three different males.) The male is simply the sperm donor, who copulates with as many females as possible; the female is responsible for nest-building and feeding her young. She removes their fecal sacs and hunts for invertebrates in the grasses and water pools within close range of her nest. Nestlings must grow rapidly to develop from naked hatchlings to fully- feathered young birds, strong enough to climb out of the nest to higher ground or perhaps onto a marsh-elder before the flooding tides occur.

Nests have a domed canopy, which does help keep eggs from flooding out of the nest at high tides. The birds need about 26 days from nest construction until fledging, and lunar flood tides happen at least once every 28 days; this leaves very little margin for survival. Increasingly, marshes are also flooding before the peak high tides and again at mid-cycle, which dooms many nests. By measuring the elevation of all the nests, we hope to determine how high above sea level they must be for eggs and nestlings to survive.

The ebb and flow of the tides are vital to the health of the salt marsh and thus the survival of the sparrows. At the southern end of Jacobs Point, tidal flow was greatly restricted by old stone culverts that had collapsed under an elevated roadbed built in the 1930s. Without the flushing of salt water, Phragmites australis, a highly invasive common reed, had spread into the marsh. Increasingly, marshes are also flooding before the peak high tides and again at mid-cycle, which dooms many nests.

Working with the Land Trust, Wenley Ferguson of Save The Bay acquired funding in 2009 from the National Oceanic and Atmospheric Administration, the Natural Resources Conservation Service, and the Coastal Resource Management Council to oversee the design and installation of three new culverts. These arched culverts have increased tidal flow and created saltier water and less suitable conditions for Phragmites by flushing out the nutrient-rich runoff it thrives in. The culverts also drained standing water from the southern high marsh, where the saltmarsh sparrow nests. However, standing water in the high marsh to the north was still killing off marsh grass and degrading the peat, thus destroying still more of the saltmarsh sparrow’s habitat.

Save The Bay documented similarly degraded high marsh in a region-wide assessment of salt marshes in 2012 to 2013. This widespread degradation is largely attributed to accelerated sea level rise. To deal with standing water in the salt marsh to the north, shallow creeks, called runnels, were dug by hand and with a low-ground- pressure excavator. The runnels now drain surface water off the marsh, and high marsh vegetation is recolonizing the bare areas. The Land Trust and Save The Bay obtained funds for this project from the Coastal Resource Management Council and the Rhode Island Department of Environmental Management.

Another goal of this ongoing restoration effort is to protect a stand of native common reed, Phragmites americanus, from a highly aggressive stand of non- native Phragmites australis, which has expanded in the last two decades due to runoff from streets and development. Both Save The Bay and the Land Trust are meeting with property owners along Jacob’s Point to discuss better ways to keep storm water runoff from roofs and parking lots from reaching the marsh. Reducing runoff and restoring more of the high marsh habitat would give the saltmarsh sparrow a leg up in its race against sea rise.

In the first nesting cycle of 2017, only one nestling was strong enough to climb out of her nest before it flooded. After the Rhode Island state motto, we nicknamed her Hope. Her name also recalls the title of Emily Dickinson’s poem, which begins, “Hope is the thing with feathers…”

Authors Steve Reinert and Deirdre Robinson hold master’s degrees in Wildlife Sciences and Biology, respectively, from the University of Rhode Island. Both have spent decades studying birds on salt marshes in southeastern New England. At Jacob’s Point, Robinson and Reinert have worked with Wenley Ferguson, the Director of Habitat Restoration for Save The Bay, to help improve the ebb and flow of the tides through the salt marsh since the late 1990s.