Domestic Chicken versus Red Junglefowl : How do We Differentiate them?

Chickens have co-existed with human beings since the early age of human civilisation. From archaeological findings in Neolithic sites, it was hypothesized that domestic chickens in South East Asia were originated from junglefowls (Hiromi sawai et al, 2010). We (the nutty birders) are very well informed that Red Junglefowl (Gallus gallus) is the wild replica of Gallus gallus domestica but how do we differentiate them when we see one in nature especially when there are also free-ranging ferals and free-ranging village chickens in the mix. In local terms how do we know whether it was an Ayam Kampung or an Ayam Hutan ?

Since the early 20th century thru the writings of Beebe (1918 to 1921) until todate, many literature have written on Gallus gallus. Topics ranging from embryonic development, social and sexual behaviors, vocalisation, habitat preference, roosting behavior to genetic variation have all been covered extensively. Unfortunately many literature until today still can't seem to agree on the actual traits of a Gallus gallus. Before you start pulling your hair or depleting your gray matter further, have a look here at what current researchers have to say on the characteristics of its conspecific domesticated descendants.

Thru the various phenotypic characters identified as signals of genetically "pure" Red Junglefowl (Gallus gallus) genomes, Brisbin & Peterson, 2007 identified a few phenotypic markers of a seemingly pure Gallus gallus. Here are the field markers mentioned:

i) the presence of red or yellow neck hackles are replaced with spatulate black feathers on an eclipse male plumage.

ii) slender, darker legs

iii) horizontal body posture 

iv) simpler and shorter calls.

The above description was also concurred by Steven Platt et al (2009) whereby an eclipse male Red Junglefowl free from domesticated influence has been described as typically having black hackles in mid-back which are not elongated in contrast to the elongated red-orange plumes of the main plumage.

From the above description and the many photos of Gallus gallus reviewed, i believed that the photos below here belongs to a Gallus gallus or locally called Ayam Hutan.

All the above photos were taken from a mangrove area (at a river estuary) near a town called Merbok, in the state of Kedah, February 2019. There were actually 3 of them and all were males. The above photos only showed two of them. The third one was hiding further away at a distance. Despite moving further away from them, they did not alight from their mangrove perch and despite that it was also near some human settlements where food should be abundant. Duration of observation was around 15 minutes.

Although all the above photos showed most of the features of a Gallus gallus in general sense but until a DNA test is done, i cannot conclude that they were all free of any domestic genes.

According to Hoa Nguyen- Phuc and Mark E. Berres (2018), wild junglefowls (adult males, females, juveniles) that hatched by domestic chickens usually do not tolerate captivity. Brisbin and Peterson (2007) have earlier explained that hybrid offspring would be expected to move far away from human settlements into the forest. Its only after 3 or 4 generations of cross breeding will the offsprings eventually tolerate a continued human presence. This findings were also supported by Rebecca Kavajamaa et al, (2018) whereby it was reported that there were some correlated effect of tameness on young Red Junglefowl when been raised by human beings.

It is also pertinent to note that Hoa Nguyen- Phuc and Mark E. Berres (2018) research also found no strong correlation between geographic distances and genetic dissimilarities among their samples collected. By using a Bayesian clustering method to establish the distribution between samples, Hoa Nguyen- Phuc and Mark E. Berres (2018) finding means that Gallus gallus found in Thailand, Vietnam, India or Indonesia for example should have the same genetic code. Meanwhile according to HBW Alive, currently there are 5 subspecies been recognised and those in Malaysia are reckoned from the Ssp G.g spadiceus.

Most researchers nevertheless agreed that hybridisation and introgression are phenomena that can threaten the genetic integrity of many wildlife.

"Genetic contamination of wild populations via hybridisation (natural or human induced) with domesticated stocks represents a serious but underappreciated concern in the conservation of biodiversity" (Brisbin, 1995; Rhymer & Simberloff, 1996 in Brisbin and Peterson, 2007)

For comparison purposes, here are photos of what i believe were some hybrid Gallus gallus:

The above photo was taken at a forest edge in Selangor in 2018.

The above photo was taken at a forest edge in Pahang in 2018

CONCLUSION

From the above photos and references adduced, all i can say here is that

"All Gallus gallus are chickens but not all chickens are Gallus gallus"

References

Brisbin and Peterson, 2007. Playing Chicken with Red Junglefowl: Identifying Phenotypic Markers of Genetic Purity in Gallus gallus. In Animal Conservation. 10 (4): 429 - 435, Nov 2007.

Hiromi Sawai et al, 2010. The Origin and Genetic Variation of Domestic Chickens with Special Reference to Junglefowl G.Gallus gallus and G. varius.  In Plosone, 2010, 5 (5),

Hoa Ngyuyen - Phuc and Mark E. Berres, 2018. Genetic Structure in Red Junglefowl (Gallus gallus) Populations: Strong spatial patterns in the wild ancestors of domestic chickens in a core distribution range. In Ecology and Evolution, 2018, July, 8 (13): 6575 - 6588.

Rebecca Katajamaa, Lovisa H. Larson, Paulina Lundberg, Ida Sorensen, Per Jensen, 2018. Activity, Social and Sexual Behavior in Red Junglefowl selected for divergent levels of fear of humans. In journal.plos.org. September, 2018.

Steven G. Platt, Tomas P. Condon, Johny S. Tasirin, Iwan Hunowu, Stephan Siwu, Richard A. Jones and Thomas R. Rainwater, 2009. Notes on red junglefowl (Gallus gallus) in Northern Sulawesi, Indonesia, with an emphasis on genetic introgression with domestic chickens. In Malayan Nature Journal 2009, (61(1), 23 - 33.