Ecology and Vulnerability

Clapper Rail

Background
Clapper rails are medium-sized, marsh-dependent birds, formerly known as salt marsh hens. Males and females are similar in plumage, but males are typically larger in size ⁸. Their geographic range extends from northeastern to western US, and as far south as Peru and Brazil. Though not abundant in New England, they have occasionally been found in Massachusetts throughout the past several decades ⁶. In southern coastal areas such as North Carolina, they are far more abundant ². Most clapper rails do not undergo distant migrations, although breeding populations from southern New England to the mid-Atlantic coast migrate, and overwinter along the southern Atlantic Coast. Historically, clapper rails were targeted by hunters, but now primarily face threats of habitat loss and pollution.

Clapper rails live in salt marshes and other coastal vegetated habitats and typically feed on crabs, mollusks, worms, small fish, and insects ⁶. They often feed along tidal flats and creek beds at night during low tide. Clapper rails are poor flyers, and prefer to walk or swim while foraging or avoiding predators ⁶. Because of their high specialization for estuarine habitat, they are often used as an indicator of coastal marsh health ⁴. Clapper Rails nest within the cover of grasses in salt marshes, above the high tide line. Nests are typically constructed from plant matter that rests on mud ⁶. Nesting locations vary by region and habitat, but can be found near tidal creeks and pools in dense vegetation ⁴.

Climate Impacts
Clapper rails are expected to be negatively impacted by climate change throughout their geographic range.  Sea level rise and storm surge are expected to damage and alter clapper rail habitat, and contribute to their overall vulnerability ^5,9. Increasing coastal storms and surge may cause populations to decline temporarily ⁸, as nests in salt marshes are highly vulnerable to flooding; however, nest height can vary in tidal and freshwater areas, thus clapper rails may be able to reduce nest mortality from flooding by using different habitats ⁷. Clapper rails, along with other tidal marsh specialists, are particularly vulnerable to marsh fragmentation and loss in areas where high marsh loss is extensive and marsh migration is hindered by adjacent development, hardened infrastructure, or sudden changes to the slope of the landscape ¹⁰. In Chesapeake Bay, clapper rails are projected to lose nearly 80% of their population with a sea level rise of 3.3 - 6.6 feet by 2100 ¹¹. Climate change is also expected to impact biological aspects of many bird populations, such as feeding patterns, migration timing and behavior, and breeding success ^1,3.