This week for Flora and Fauna Friday it’s a big duck from the Southeast with some baggage to unpack, the Mottled Duck (Anas fulvigula).
Feathers floating on winter waters, far-flung waterfowl can be found wary on our frigid wetlands every season. Amongst their numerous and cherished forms one dabbling duck looms above the rest, its newfound presence relegated to the margins of the marsh. The Mottled Duck is a large dabbler with a cryptic plumage. Their body is covered from tail tip to shoulders in a sea of two-tone feathers, ebony-black within and chestnut-brown around. At the throat the feathers lighten to a rich and textured khaki as they rise to a black, beaded eye. That eye is set at the summit of a darker arching stripe below a canopy of the duck’s darkened crown. The sole accent to break up this brindling of browns is a bill painted golden-yellow, save for a black tipped nail. On land, orange legs glow from below. In flight, iridescent indigo speculums shimmer atop the wings’ secondary feathers and below silver plates the wings’ entirety. Males and females look practically identical, save for the female’s yellow-orange bill. Amongst our Lowcountry ducks, the Mottled Duck stands out. Not just for its commitment to camouflage but because it’s just plain bigger.
The Mottled Duck is one of the Lowcountry’s only year-round duck residents, alongside the Wood Duck, a few Hooded Mergansers, and the nomadic Black-bellied Whistling-Duck. Mottled ducks can be found throughout southern Florida, and the tidal regions of the Gulf Coast, Georgia, and South Carolina. They are specialists adapted to our expansive brackish and freshwater marshes. They’ve also taken quite a liking to rice fields and shallow saltwater impoundments. They’re most easily spotted gliding along the fringes of open water in a brackish marsh, drifting out of view once they make eye contact with you. Mottled Ducks are powerful fliers, exploding up from the water when startled. As a true dabbler, they quack. A deep, loud, and quintessential quack.
The Mottled Duck’s history in South Carolina is a very recent and deliberate one. It’s a history rife with nuanced and complex discussions of conservation ethics, competing priorities, and long-term ecological ripple effects. So let’s dive on in and dabble in this duck’s legacy.
To begin, Mottled Ducks, like many wetland dependent species, have experienced extensive habitat loss from the draining, dredging, and damming of wetlands. These wetlands have also been further degraded by coastal development, water pollution, and aquatic invasive species. Additionally, as these ducks are non-migratory, localized habitat impacts have compounding effects on populations, as these birds rely on the same wetlands year in and year out. Now, they are also being threatened by rising seas. As a duck specially adapted for life in a narrow belt of habitat, which could be defined as where water meets land and seawater meets freshwater, the prospect of rapidly rising sea levels could drown out Mottled Ducks faster than the brackish marshes they rely on can migrate uphill.
The Mottled Duck is a close relative to the Mallard (Anas platyrhynchos). Female Mallards and Mottled Ducks also look incredibly similar. Yet, madam Mallard is one shade lighter with a darker orange bill and Ms. Mottled Duck a bit bigger. In fact, the two species can, and readily do, hybridize. This has become a problem for the Mottled Duck. Historically, Mallards did not breed in the southeast, similar to how Canada Geese used to be. Mallards were winter migrants. Over the centuries, a combination of pond creation, building of rice fields, the introduction of tame farm-raised Mallards from Europe, and restocking efforts all resulted in the materialization of resident Mallard populations in the Southeast. These resident Mallard populations have now become something not quite native. Resident Mallards began to wander south, pair up with Mottled Ducks, and raise hybrid offspring called “Muddled Ducks”. This interspecies gene flow can be a problem for the more habitat specialized Mottled Ducks as this influx of Mallard genes can result in hybrid offspring that are no longer fit for a life upon the brine of the sun-soaked southern marsh. This genetic admixture combined with the aforementioned habitat loss put Mottled Ducks in a precarious place.
To further complicate this, the Mottled Ducks in South Carolina were deliberately introduced in the late 1970s and early 1980s. This was to create a stable satellite population to serve as both a new game bird for the state and a disjunct reservoir population. In South Carolina, they’ve actually thrived in the rice fields and brackish marshes of the Lowcountry and have begun to colonize new habitats along the coast, to include Edisto Island. However, the ducks transplanted to South Carolina came from across their range in the United States and included both of the distinct subspecies. Although not as worrisome as the muddled Mallard hybrids, these translocated Lowcountry Mottled Ducks are now beginning to spread south towards the natural Florida populations. This flow of Gulf Coast Mottled Duck genes into the Florida Mottled Duck populations could compound with the flow of Mallard genes to eventually dissolve the Florida subspecies out of existence. That sounds pretty doom and gloom but, in the long run looking at a species level, this manmade population in South Carolina has still succeeded at its goal, given the Mottled Ducks here are thriving in the bounty of our conserved coastal wetlands. This new Eden in the ACE may serve as one of the last bastions for the species, as threats surround them on all sides.
