Saltmarsh Sparrow

There are a handful of sparrows that use salt marshes, but the Saltmarsh Sparrow is arguably the one most deserving of the moniker. For its entire life, this secretive bird is rarely far from tidal marshes dominated by a few types of specialized grasses. Saltmarsh Sparrows breed in a narrow band along the coast from southern Maine to Chesapeake Bay, and winter in an equally narrow band from New Jersey to Florida. They can even drink salty water (or consume salty prey) without the negative consequences found in closely related species.

During the breeding season, Saltmarsh Sparrows are at the mercy of the tides. They build their nests barely about the high-water mark, which sets them up at risk of flooding during the exceptional high tides that come with the full moon. Sometimes nests can survive a short period of inundation, but most fail and the birds re-nest quite rapidly. At this point the local population becomes highly synchronized, and the combination of their incubation and nestling periods is just short enough to wrap up before the next extreme high tide. All this occurs in a fairly restricted zone in most marshes: nests too close to the tidal channels risk more extreme flooding while those closer to higher ground are more vulnerable to predation at low tide.

This system has served the sparrows well for thousands of years, but in the last few hundred people have acted in multiple ways to make life in the marshes more and more difficult. Early on we dug ditches to drain marshes for agriculture, or in misguided efforts to control mosquito populations, and today these ditches increase the risk or flooding and can gradually degrade the marsh. Efforts are underway to mitigate these old wounds, but we are now in a dangerous race against rising sea levels caused by climate change. In a system finely tuned to allow successful nesting between monthly “king tides,” any rise in the baseline water level could result in widespread reproductive failure. It should come as no surprise that Saltmarsh Sparrow populations are in steep decline and may disappear from a large portion of their range by the end of the century.