For generations, cattle on Trinket Island were part of human life in India's Nicobar archipelago. Then, on Dec. 26, 2004, a massive earthquake and tsunami struck the Andaman and Nicobar Islands, devastating Trinket and forcing its human population to leave. The cattle were left behind.

The cattle's story took an unexpected turn, as the animals were left to survive on their own after the tsunami. Once cared for by people, they became completely feral, adapting to life on the isolated island. By 2020, researchers reported that only about 150 descendants remained, leaving the herd highly vulnerable to extinction. From Danish livestock to island cattleThe story of Trinket's cattle began more than two centuries before the tsunami. The 2020 Journal of Genetics paper, citing a 1903 account by Kloss, said Danish colonists introduced cattle to the island between 1756 and 1768 apparently to provide milk.

The animals were initially managed by the colonial settlers, but that arrangement changed after Danish control ended. The indigenous Nicobarese subsequently cared for the herd but primarily valued cattle for meat rather than milk. Over time, the animals became semi-feral. The report said researchers noted nearly 50 semi-wild cows on Trinket Island in the early 20th century. These cows also helped transform the island’s landscape. The researchers stated that part of the forest on Trinket Island was transformed into grassland by the Danes, which would act as fodder for the cows. Therefore, this historical context shows the herd was more than simply cattle left behind after the tsunami. What happened after the tsunami?

The 2004 disaster changed the cattle's relationship with people almost overnight. Trinket was among the islands severely affected by the tsunami, and the surviving inhabitants were evacuated to neighboring islands. With no human community left to manage the animals, the cattle became completely feral.

Unlike conventional cattle, the animals no longer depended on people for regular feeding, breeding management, or veterinary care. They had to find food and shelter themselves, while living within the limits of a small island environment.

The population's precarious condition was documented in The Indian Journal of Animal Sciences. Researchers examined blood-based indicators including hematological values, serum biochemistry, and mineral profiles. The measurements fell within normal physiological ranges and provided baseline data for future health assessments. The same paper reported that only around 150 descendants were then known to exist. That number placed the cattle close to the edge of extinction and highlighted the need for conservation measures. What does their DNA reveal?

The cattle's unusual history also prompted researchers to investigate where they came from genetically. Scientists also examined mitochondrial DNA, focusing on the D-loop and cytochrome b regions. The analysis placed Trinket cattle within the Bos indicus lineage and identified them as the I2 sub-haplotype. Researchers suggested that this genetic signature may reflect the historical movement of the I2 lineage toward Southeast Asia. The finding offered a way to distinguish the isolated island population from other cattle and provided information that could be useful for conservation breeding.

The Trinket cattle also carry the legacy of a colonial experiment that outlasted its original purpose. Their history reflects shifting human dynamics, transitioning from colonial livestock management to indigenous husbandry to total post-tsunami abandonment. The existence of just about 150 of these animals, as recorded in the 2020 study, is indicative of the rapid rate at which such unique genetic inheritance can be lost.