The Feral Chickens of Kauai

When we landed in Kauia, Hawaii, I waited with the bags while my wife went to pick up the rental car.  

Several small gaggles of apparently feral chickens hunted and pecked around the outside of the terminal, and as I watched them, I could not help notice that while the roosters were magnificent, the hens were small, colored like wild game birds, and had very little comb or crest.

“These chickens look a lot like Red Jungle Fowl,” I remarked to my wife, theorizing that the feral chickens of Kauai had drifted back to their ancient genetic roots.

Feral chickens are all over Kauai. They are at every parking lot, beach, and roadside pull over.  There’s an amazing number of chickens on the island, and though there is some variety, the Red Jungle Fowl look I had seen at the airport, seemed quite common all over.

Intrigued, I googled Kauai feral chickens and discovered a 2023 study entitled “Population structure and hybridisation in a population of Hawaiian feral chickens,” which is a historical and genetic analysis of Kauai’s feral chickens.  

Perfect!

Chickens are believed to have inhabited the Hawaiian island of Kauai since the first human migrations around 1200AD, but numbers have peaked since the tropical storms Iniki and Iwa in the 1980s and 1990s that destroyed almost all the chicken coops on the island and released large numbers of domestic chickens into the wild. Previous studies have shown these now feral chickens are an admixed population between Red Junglefowl (RJF) and domestic chickens. Here, using genetic haplotypic data, we estimate the time of the admixture event between the feral population on the island and the RJF to 1981 (1976–1995), coinciding with the timings of storm Iwa and Iniki. Analysis of genetic structure reveals a greater similarity between individuals inhabiting the northern and western part of the island to RJF than individuals from the eastern part of the island. These results point to the possibility of introgression events between feral chickens and the wild chickens in areas surrounding the Koke’e State Park and the Alaka’i plateau, posited as two of the major RJF reservoirs in the island….

On the island of Kauai, in the Hawaiian archipelago, chickens first arrived in AD 1200, when the Polynesian settlers brought Red Junglefowl (RJF), the wild-type chicken, with them (Kirch 2011; Thomson et al. (2014). The second known arrival of RJF onto the island occurred in 1939 when 857 Pacific RJF were intentionally released into the wild, to maintain the naturalised population, which suffered a large reduction in their numbers because of the increased hunting and predation pressure introduced by the European settlers (Pyle and Pyle 2017). To this day, chickens in Koke’e State Park are referred to as Moa and are considered to be descended from the RJF that were originally brought over by the Polynesian settlers (Denny 1999; as cited in Pyle and Pyle 2017). These are believed to be the reservoir population for the RJF alleles that are now seen in the feral populations on the island.

The weird part of this study was that it was done in Sweden from a sample of 23 feral chickens “donated by private individuals” from Kauai in 2013, and imported to Sweden.

It should be said that Kauai’s feral chicken population is unrestrained by native predators of any kind.  Only cats, dogs, people, and cars impact chicken population dynamics, and it’s clear from the number of chicks running around that reproduction is higher than even the feral cats can keep up with.  

While there are no fox, raccoon, coyote, or snakes on any of the Hawaiian islands, mongoose were introduced from Jamaica in the 1870s, first in Maui, then Molokai, Oahu, and then the big island of Hawaii.  But mongoose were never introduced to Kauai — one reason the bird population of this island is more robust than on the others.

In fact, I suspect the ubiquitous nature of feral chicken chicks takes the pressure off cat predation off native and imported song birds — a bonus.