Day 9 of Avian August 2025, Birds of Hawaii, hosted by @cookiedoves: Koloa or Hawaiian Duck (Anas wyvilliana)
The koloa is found only on the Hawaiian Islands, with around 90% of the population living on Kaua‘i. They are closely related to mallards but are recognized as their own species. Genetic studies suggest they originated from ancient hybridization between mallards and Laysan ducks.
In addition to the usual dangers from introduced mongooses, rats, cats, and dogs, hybridization with introduced mallards is another major threat to the Hawaiian duck’s survival. Mallards were brought to Hawaii within the past couple of hundred years for hunting and ornamental purposes, and have rapidly diluted the koloa’s genetic lineage. Kaua‘i’s large population is largely due to the absence of mallards on the island.
*Fish featured is a native Hawaiian freshwater goby species, 'O'opu Nakea (Awaous stamineus)
