The Sparrow That Acts as an Early Warning Signal

Saltmarsh sparrow nests in the marshes of the Sound.
Saltmarsh sparrows nest in the marshes of the Sound. Photo by Patrick Comins.

The saltmarsh sparrow faces many threats to its survival. Development along the coast has replaced much of its tidal habitat. Contaminants and invasive species such as Phragmites degrade some of the habitat that is left. But the most critical threat, says Chris Elphick, an ornithologist and conservation biologist at the University of Connecticut, might now be the impact sea level rise has on the sparrow’s ability to reproduce.

Saltmarsh sparrows build their nests, lay their eggs and raise their young in the high marsh vegetation of tidal wetlands, close to the water’s edge. If they complete this whole process within 26 days, their young are likely to succeed before the extremely high tides of the month wash away the nests. But an increase of sea-level rise of even a couple of inches will likely mean more nests will wash away, and the species’ reproductive success will decline.

“We know that sea-level rise is going to keep on increasing for the next few decades, so with the rising sea level, the frequency with which nests are likely to flood is going to go up and that means the birds face a very uncertain future,” said Elphick, during a site visit to one of the prime Long Island Sound habitats for tidal marsh birds, the Barn Island Wildlife Management Area in Stonington, CT.

Elphick has been studying the saltmarsh sparrow, identified as Vulnerable BirdLife International, in Connecticut marshes for more than 10 years. Most of the sparrows breed in the northeast United States where a network of scientists, including Elphick, collaborate to monitor the health of tidal marsh birds and their habitat through the Saltmarsh Habitat and Avian Research Program. This group recently estimated the global population to be a little over 50,000 individuals.

In 2012, Elphick’s research was funded by the Long Island Sound Sentinel Monitoring for Climate Change Program. The Program sought to develop pilot “sentinel” indicators that would act as early warning signals to detect the impact of climate change in the Long Island Sound ecosystem. Sentinel indicators include species or habitats considered particularly vulnerable to climate change impacts in Long Island Sound.

Elphick and his co-investigator, Chris Field, at the time a PhD student at University of Connecticut, along with Min Huang of the Connecticut Department of Energy and Environmental Protection and colleagues from the University of Maine, were awarded a two-year grant that included monitoring the saltmarsh sparrow and three other tidal wetland birds at 141 marshland sites in Long Island Sound. Of the four birds studied, the saltmarsh sparrow is the most affected by high tides because they nest lower in saltmarsh vegetation.

“Saltmarsh sparrows are particularly sensitive to those flooding effects,” said Elphick. “They are like an early warning system. They are like the canary in the coal mine in that they tell us that things are changing.”

Elphick added, “They will be affected before everything else is affected, and so by studying this one species that most people have probably never heard of, we can learn something about the entire marsh system and how these marshes are going to fare in the future.”

Besides the tidal marsh birds, Elphick and Field studied other potential sentinels for the Sentinel Monitoring strategy, including beach-nesting birds, waterbirds that nest in coastal forests, and saltmarsh vegetation. Their findings are posted in the Climate Change and Sentinel Monitoring research projects section of the Long Island Sound Study website.

Watch a video of Chris Elphick discuss saltmarsh sparrows and climate change at the Barn Island Wildlife Management Area.

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