Feral chickens, rampant in many areas of the island, appear to show hardier immune systems than their domesticated counterparts, a scientific study has found.

The findings appeared in the latest edition of Poultry Science online, where the insides of 21 feral chickens collected in the East End were compared with samples of 12 broiler chickens from the Department of Animal Sciences at the University of Illinois.

Researchers said they picked Bermuda’s feral chicken because “it represents one of the long-established feral chicken populations with minimal human intervention, which makes it an ideal model for studying feral chickens”.

The study noted that the island supports “a large, self-sustaining population of feral chickens that have been living in the wild since at least the mid-1980s”.

It said the birds look to be descended from “an admixed flock originating from several breeds that are popular sources for meat and egg production in the Western hemisphere”.

The publication said that, because the feral chicken has “persisted without human management or artificial selection for several decades, it represents a rare and valuable opportunity to examine how sustained exposure to a diverse and unmanaged microbial environment shapes host immune function”.

Chickens in the wild, a familiar nuisance for decades, have come under political fire in recent years as well as drawing the ire of Bermuda’s farmers.

While the birds have traditionally been culled, and can legally be destroyed, the Ministry of Public Works and Environment deployed apps to work in tandem with traps in December 2025 to go beyond the roughly 1,300 feral chickens removed each month by the Department of Environment and Natural Resources.

As of yesterday, the DENR feral bird dashboard online showed 39 service requests over the last 30 days: 36 for chickens and three for pigeons. There were 82 control actions listed, with 206 chickens accounted for.

For the research paper, intestinal samples were deep frozen and subjected to genetic analysis in the US. Liver samples were also studied.

The feral chickens came out on top in terms of microbial diversity, compared with broiler chickens.

The populations also carried different bacterial populations in their innards, and the immune systems of the feral chickens appeared to reflect “adaptation to microbial rich environments” — in keeping with birds living and feeding out in the open.

Feral chickens showed internal inflammation that might serve as a defensive barrier in their pathogen-rich environment.

The study added: “Diets of feral chickens are composed of insects, seeds, vegetation and anthropogenic waste that might drive both microbial and immune variation.”

Surviving in the wild appeared to have reactivated “innate immune pathways”, while domestic chickens come with “reduced genetic and microbial diversity that compromises immune response”.

When it came to chickens as carriers of disease, the researchers concluded that studies based on domestic chickens would likely give a less detailed picture of the pathogen dynamics among feral chickens.

The study suggested that exposing domestic chickens to a greater microbial diversity could boost their immune strength.

Poultry Science is a monthly scientific journal published by the Dutch academic company Elsevier, Inc on behalf of the US-based Poultry Science Association.